Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.
Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.
The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.
The selecting and organizing of visual stimuli based on the individual's past experience.
Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.
The total area or space visible in a person's peripheral vision with the eye looking straightforward.
The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.
Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.
Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.
The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)
The absence or restriction of the usual external sensory stimuli to which the individual responds.
The functional superiority and preferential use of one eye over the other. The term is usually applied to superiority in sighting (VISUAL PERCEPTION) or motor task but not difference in VISUAL ACUITY or dysfunction of one of the eyes. Ocular dominance can be modified by visual input and NEUROTROPHIC FACTORS.
The rostral part of the frontal lobe, bounded by the inferior precentral fissure in humans, which receives projection fibers from the MEDIODORSAL NUCLEUS OF THE THALAMUS. The prefrontal cortex receives afferent fibers from numerous structures of the DIENCEPHALON; MESENCEPHALON; and LIMBIC SYSTEM as well as cortical afferents of visual, auditory, and somatic origin.
Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.
Part of the DIENCEPHALON inferior to the caudal end of the dorsal THALAMUS. Includes the lateral geniculate body which relays visual impulses from the OPTIC TRACT to the calcarine cortex, and the medial geniculate body which relays auditory impulses from the lateral lemniscus to the AUDITORY CORTEX.
Images seen by one eye.
The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.
Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.
Awareness of oneself in relation to time, place and person.
Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
The region of the cerebral cortex that receives the auditory radiation from the MEDIAL GENICULATE BODY.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Area of the FRONTAL LOBE concerned with primary motor control located in the dorsal PRECENTRAL GYRUS immediately anterior to the central sulcus. It is comprised of three areas: the primary motor cortex located on the anterior paracentral lobule on the medial surface of the brain; the premotor cortex located anterior to the primary motor cortex; and the supplementary motor area located on the midline surface of the hemisphere anterior to the primary motor cortex.
Area of the parietal lobe concerned with receiving sensations such as movement, pain, pressure, position, temperature, touch, and vibration. It lies posterior to the central sulcus.
The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.
The time from the onset of a stimulus until a response is observed.
The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.
A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of 16 species inhabiting forests of Africa, Asia, and the islands of Borneo, Philippines, and Celebes.
Behavioral manifestations of cerebral dominance in which there is preferential use and superior functioning of either the left or the right side, as in the preferred use of the right hand or right foot.
The awareness of the spatial properties of objects; includes physical space.
Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating.
The real or apparent movement of objects through the visual field.
A subjective visual sensation with the eyes closed and in the absence of light. Phosphenes can be spontaneous, or induced by chemical, electrical, or mechanical (pressure) stimuli which cause the visual field to light up without optical inputs.
The blending of separate images seen by each eye into one composite image.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.
Semidomesticated variety of European polecat much used for hunting RODENTS and/or RABBITS and as a laboratory animal. It is in the subfamily Mustelinae, family MUSTELIDAE.
The coordination of a sensory or ideational (cognitive) process and a motor activity.
A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction.
Neural tracts connecting one part of the nervous system with another.
The science dealing with the correlation of the physical characteristics of a stimulus, e.g., frequency or intensity, with the response to the stimulus, in order to assess the psychologic factors involved in the relationship.
A species of the genus MACACA inhabiting India, China, and other parts of Asia. The species is used extensively in biomedical research and adapts very well to living with humans.
A species of the genus MACACA which typically lives near the coast in tidal creeks and mangrove swamps primarily on the islands of the Malay peninsula.
The positioning and accommodation of eyes that allows the image to be brought into place on the FOVEA CENTRALIS of each eye.
Processes and properties of the EYE as a whole or of any of its parts.
Posterior portion of the CEREBRAL HEMISPHERES responsible for processing visual sensory information. It is located posterior to the parieto-occipital sulcus and extends to the preoccipital notch.
The function of opposing or restraining the excitation of neurons or their target excitable cells.
The sensory discrimination of a pattern shape or outline.
The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of EYE DISEASES; OPTIC NERVE DISEASES; OPTIC CHIASM diseases; or BRAIN DISEASES affecting the VISUAL PATHWAYS or OCCIPITAL LOBE.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
Upper central part of the cerebral hemisphere. It is located posterior to central sulcus, anterior to the OCCIPITAL LOBE, and superior to the TEMPORAL LOBES.
The absence of light.
Voluntary or reflex-controlled movements of the eye.
Differential response to different stimuli.
Dominance of one cerebral hemisphere over the other in cerebral functions.
Method of measuring and mapping the scope of vision, from central to peripheral of each eye.
An outbred strain of rats developed in 1915 by crossing several Wistar Institute white females with a wild gray male. Inbred strains have been derived from this original outbred strain, including Long-Evans cinnamon rats (RATS, INBRED LEC) and Otsuka-Long-Evans-Tokushima Fatty rats (RATS, INBRED OLETF), which are models for Wilson's disease and non-insulin dependent diabetes mellitus, respectively.
Lower lateral part of the cerebral hemisphere responsible for auditory, olfactory, and semantic processing. It is located inferior to the lateral fissure and anterior to the OCCIPITAL LOBE.
Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).
Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
Elements of limited time intervals, contributing to particular results or situations.
Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain.
Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.
Cerebral cortex region on the medial aspect of the PARAHIPPOCAMPAL GYRUS, immediately caudal to the OLFACTORY CORTEX of the uncus. The entorhinal cortex is the origin of the major neural fiber system afferent to the HIPPOCAMPAL FORMATION, the so-called PERFORANT PATHWAY.
Large mass of nuclei forming the most caudal portion of the THALAMUS and overhanging the GENICULATE BODIES and the dorsolateral surface of the MIDBRAIN. It is divided into four parts: the lateral, medial, inferior, and oral pulvinar nuclei.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The minimum amount of stimulus energy necessary to elicit a sensory response.
Perception of three-dimensionality.
Use of electric potential or currents to elicit biological responses.
A genus of the family Lorisidae having four species which inhabit the forests and bush regions of Africa south of the Sahara and some nearby islands. The four species are G. alleni, G. crassicaudatus, G. demidovii, and G. senegalensis. There is another genus, Euoticus, containing two species which some authors have included in the Galago genus.
A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.
The anterior pair of the quadrigeminal bodies which coordinate the general behavioral orienting responses to visual stimuli, such as whole-body turning, and reaching.
Use of sound to elicit a response in the nervous system.
The part of the cerebral hemisphere anterior to the central sulcus, and anterior and superior to the lateral sulcus.
The misinterpretation of a real external, sensory experience.
Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)
The outer zone of the KIDNEY, beneath the capsule, consisting of KIDNEY GLOMERULUS; KIDNEY TUBULES, DISTAL; and KIDNEY TUBULES, PROXIMAL.
A technique that involves the use of electrical coils on the head to generate a brief magnetic field which reaches the CEREBRAL CORTEX. It is coupled with ELECTROMYOGRAPHY response detection to assess cortical excitability by the threshold required to induce MOTOR EVOKED POTENTIALS. This method is also used for BRAIN MAPPING, to study NEUROPHYSIOLOGY, and as a substitute for ELECTROCONVULSIVE THERAPY for treating DEPRESSION. Induction of SEIZURES limits its clinical usage.
The surgical removal of the eyeball leaving the eye muscles and remaining orbital contents intact.
A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. STRABISMUS and REFRACTIVE ERRORS may cause this condition. Toxic amblyopia is a disorder of the OPTIC NERVE which is associated with ALCOHOLISM, tobacco SMOKING, and other toxins and as an adverse effect of the use of some medications.
Low molecular weight, calcium binding muscle proteins. Their physiological function is possibly related to the contractile process.
An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.
The difference between two images on the retina when looking at a visual stimulus. This occurs since the two retinas do not have the same view of the stimulus because of the location of our eyes. Thus the left eye does not get exactly the same view as the right eye.
A localized defect in the visual field bordered by an area of normal vision. This occurs with a variety of EYE DISEASES (e.g., RETINAL DISEASES and GLAUCOMA); OPTIC NERVE DISEASES, and other conditions.
The measurement of magnetic fields over the head generated by electric currents in the brain. As in any electrical conductor, electric fields in the brain are accompanied by orthogonal magnetic fields. The measurement of these fields provides information about the localization of brain activity which is complementary to that provided by ELECTROENCEPHALOGRAPHY. Magnetoencephalography may be used alone or together with electroencephalography, for measurement of spontaneous or evoked activity, and for research or clinical purposes.
Projection neurons in the CEREBRAL CORTEX and the HIPPOCAMPUS. Pyramidal cells have a pyramid-shaped soma with the apex and an apical dendrite pointed toward the pial surface and other dendrites and an axon emerging from the base. The axons may have local collaterals but also project outside their cortical region.
Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.
Partial or complete loss of vision in one half of the visual field(s) of one or both eyes. Subtypes include altitudinal hemianopsia, characterized by a visual defect above or below the horizontal meridian of the visual field. Homonymous hemianopsia refers to a visual defect that affects both eyes equally, and occurs either to the left or right of the midline of the visual field. Binasal hemianopsia consists of loss of vision in the nasal hemifields of both eyes. Bitemporal hemianopsia is the bilateral loss of vision in the temporal fields. Quadrantanopsia refers to loss of vision in one quarter of the visual field in one or both eyes.
An illusion of vision usually affecting spatial relations.
The process whereby auditory stimuli are selected, organized, and interpreted by the organism.
The superficial GRAY MATTER of the CEREBELLUM. It consists of two main layers, the stratum moleculare and the stratum granulosum.
An abrupt voluntary shift in ocular fixation from one point to another, as occurs in reading.
The study of systems which respond disproportionately (nonlinearly) to initial conditions or perturbing stimuli. Nonlinear systems may exhibit "chaos" which is classically characterized as sensitive dependence on initial conditions. Chaotic systems, while distinguished from more ordered periodic systems, are not random. When their behavior over time is appropriately displayed (in "phase space"), constraints are evident which are described by "strange attractors". Phase space representations of chaotic systems, or strange attractors, usually reveal fractal (FRACTALS) self-similarity across time scales. Natural, including biological, systems often display nonlinear dynamics and chaos.
Refers to animals in the period of time just after birth.
Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.
The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.
Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.
Paired bodies containing mostly GRAY MATTER and forming part of the lateral wall of the THIRD VENTRICLE of the brain.
The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.
The anterior portion of the head that includes the skin, muscles, and structures of the forehead, eyes, nose, mouth, cheeks, and jaw.
The only family of the order SCANDENTIA, variously included in the order Insectivora or in the order Primates, and often in the order Microscelidea, consisting of five genera. They are TUPAIA, Ananthana (Indian tree shrew), Dendrogale (small smooth-tailed tree shrew), Urogale (Mindanao tree shrew), and Ptilocercus (pen-tailed tree shrew). The tree shrews inhabit the forest areas of eastern Asia from India and southwestern China to Borneo and the Philippines.
Misalignment of the visual axes of the eyes. In comitant strabismus the degree of ocular misalignment does not vary with the direction of gaze. In noncomitant strabismus the degree of misalignment varies depending on direction of gaze or which eye is fixating on the target. (Miller, Walsh & Hoyt's Clinical Neuro-Ophthalmology, 4th ed, p641)
A suborder of PRIMATES consisting of six families: CEBIDAE (some New World monkeys), ATELIDAE (some New World monkeys), CERCOPITHECIDAE (Old World monkeys), HYLOBATIDAE (gibbons and siamangs), CALLITRICHINAE (marmosets and tamarins), and HOMINIDAE (humans and great apes).
EEG phase synchronization of the cortical brain region (CEREBRAL CORTEX).
The most common inhibitory neurotransmitter in the central nervous system.
Sensation of making physical contact with objects, animate or inanimate. Tactile stimuli are detected by MECHANORECEPTORS in the skin and mucous membranes.
The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
Learning that is manifested in the ability to respond differentially to various stimuli.
Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory.
Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.
Optical imaging techniques used for recording patterns of electrical activity in tissues by monitoring transmembrane potentials via FLUORESCENCE imaging with voltage-sensitive fluorescent dyes.
Relatively permanent change in behavior that is the result of past experience or practice. The concept includes the acquisition of knowledge.
Depolarization of membrane potentials at the SYNAPTIC MEMBRANES of target neurons during neurotransmission. Excitatory postsynaptic potentials can singly or in summation reach the trigger threshold for ACTION POTENTIALS.
Total loss of vision in all or part of the visual field due to bilateral OCCIPITAL LOBE (i.e., VISUAL CORTEX) damage or dysfunction. Anton syndrome is characterized by the psychic denial of true, organic cortical blindness. (Adams et al., Principles of Neurology, 6th ed, p460)
The outer layer of the adrenal gland. It is derived from MESODERM and comprised of three zones (outer ZONA GLOMERULOSA, middle ZONA FASCICULATA, and inner ZONA RETICULARIS) with each producing various steroids preferentially, such as ALDOSTERONE; HYDROCORTISONE; DEHYDROEPIANDROSTERONE; and ANDROSTENEDIONE. Adrenal cortex function is regulated by pituitary ADRENOCORTICOTROPIN.
An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)
Wave-like oscillations of electric potential between parts of the brain recorded by EEG.
A calbindin protein that is differentially expressed in distinct populations of NEURONS throughout the vertebrate and invertebrate NERVOUS SYSTEM, and modulates intrinsic neuronal excitability and influences LONG-TERM POTENTIATION. It is also found in LUNG, TESTIS, OVARY, KIDNEY, and BREAST, and is expressed in many tumor types found in these tissues. It is often used as an immunohistochemical marker for MESOTHELIOMA.
The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed)
One of the convolutions on the medial surface of the CEREBRAL HEMISPHERES. It surrounds the rostral part of the brain and CORPUS CALLOSUM and forms part of the LIMBIC SYSTEM.
The knowledge or perception that someone or something present has been previously encountered.
A mechanism of communication within a system in that the input signal generates an output response which returns to influence the continued activity or productivity of that system.
Remembrance of information for a few seconds to hours.
A genus of the subfamily CALLITRICHINAE occurring in forests of Brazil and Bolivia and containing seventeen species.
The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness.
Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.
The sensory interpretation of the dimensions of objects.
Cognitive disorders characterized by an impaired ability to perceive the nature of objects or concepts through use of the sense organs. These include spatial neglect syndromes, where an individual does not attend to visual, auditory, or sensory stimuli presented from one side of the body.
Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.
Tests designed to assess neurological function associated with certain behaviors. They are used in diagnosing brain dysfunction or damage and central nervous system disorders or injury.
Most generally any NEURONS which are not motor or sensory. Interneurons may also refer to neurons whose AXONS remain within a particular brain region in contrast to projection neurons, which have axons projecting to other brain regions.
A state in which there is an enhanced potential for sensitivity and an efficient responsiveness to external stimuli.
The illumination of an environment and the arrangement of lights to achieve an effect or optimal visibility. Its application is in domestic or in public settings and in medical and non-medical environments.
Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).
The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
The circulation of blood through the BLOOD VESSELS of the BRAIN.
A persistent activity-dependent decrease in synaptic efficacy between NEURONS. It typically occurs following repeated low-frequency afferent stimulation, but it can be induced by other methods. Long-term depression appears to play a role in MEMORY.
Stiff hairs projecting from the face around the nose of most mammals, acting as touch receptors.
A series of tests used to assess various functions of the eyes.
The X-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes.
The act of "taking account" of an object or state of affairs. It does not imply assessment of, nor attention to the qualities or nature of the object.
Psychophysical technique that permits the estimation of the bias of the observer as well as detectability of the signal (i.e., stimulus) in any sensory modality. (From APA, Thesaurus of Psychological Index Terms, 8th ed.)
A class of ionotropic glutamate receptors characterized by affinity for N-methyl-D-aspartate. NMDA receptors have an allosteric binding site for glycine which must be occupied for the channel to open efficiently and a site within the channel itself to which magnesium ions bind in a voltage-dependent manner. The positive voltage dependence of channel conductance and the high permeability of the conducting channel to calcium ions (as well as to monovalent cations) are important in excitotoxicity and neuronal plasticity.
Act of eliciting a response from a person or organism through physical contact.
The lectin wheatgerm agglutinin conjugated to the enzyme HORSERADISH PEROXIDASE. It is widely used for tracing neural pathways.
The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.
The detailed examination of observable activity or behavior associated with the execution or completion of a required function or unit of work.
Devices that help people with impaired sensory responses.
The electrical properties, characteristics of living organisms, and the processes of organisms or their parts that are involved in generating and responding to electrical charges.
A genus of the family CEBIDAE consisting of four species: S. boliviensis, S. orstedii (red-backed squirrel monkey), S. sciureus (common squirrel monkey), and S. ustus. They inhabit tropical rain forests in Central and South America. S. sciureus is used extensively in research studies.
Several groups of nuclei in the thalamus that serve as the major relay centers for sensory impulses in the brain.
The scientific discipline concerned with the physiology of the nervous system.
A convolution on the inferior surface of each cerebral hemisphere, lying between the hippocampal and collateral sulci.
A pyridoxal-phosphate protein that catalyzes the alpha-decarboxylation of L-glutamic acid to form gamma-aminobutyric acid and carbon dioxide. The enzyme is found in bacteria and in invertebrate and vertebrate nervous systems. It is the rate-limiting enzyme in determining GAMMA-AMINOBUTYRIC ACID levels in normal nervous tissues. The brain enzyme also acts on L-cysteate, L-cysteine sulfinate, and L-aspartate. EC
Partial or total removal, ablation, or destruction of the cerebral cortex; may be chemical. It is not used with animals that do not possess a cortex, i.e., it is used only with mammals.
Intellectual or mental process whereby an organism obtains knowledge.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.
The directed transport of ORGANELLES and molecules along nerve cell AXONS. Transport can be anterograde (from the cell body) or retrograde (toward the cell body). (Alberts et al., Molecular Biology of the Cell, 3d ed, pG3)
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
A calbindin protein found in many mammalian tissues, including the UTERUS, PLACENTA, BONE, PITUITARY GLAND, and KIDNEYS. In intestinal ENTEROCYTES it mediates intracellular calcium transport from apical to basolateral membranes via calcium binding at two EF-HAND MOTIFS. Expression is regulated in some tissues by VITAMIN D.
A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
A species of macaque monkey that mainly inhabits the forest of southern India. They are also called bonnet macaques or bonnet monkeys.
The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)
Sense of awareness of self and of the environment.
Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.
Broad plate of dense myelinated fibers that reciprocally interconnect regions of the cortex in all lobes with corresponding regions of the opposite hemisphere. The corpus callosum is located deep in the longitudinal fissure.
A persistent increase in synaptic efficacy, usually induced by appropriate activation of the same synapses. The phenomenological properties of long-term potentiation suggest that it may be a cellular mechanism of learning and memory.
The largest portion of the CEREBRAL CORTEX in which the NEURONS are arranged in six layers in the mammalian brain: molecular, external granular, external pyramidal, internal granular, internal pyramidal and multiform layers.
A new pattern of perceptual or ideational material derived from past experience.
A mechanism of communicating one's own sensory system information about a task, movement or skill.
A multisubunit enzyme complex containing CYTOCHROME A GROUP; CYTOCHROME A3; two copper atoms; and 13 different protein subunits. It is the terminal oxidase complex of the RESPIRATORY CHAIN and collects electrons that are transferred from the reduced CYTOCHROME C GROUP and donates them to molecular OXYGEN, which is then reduced to water. The redox reaction is simultaneously coupled to the transport of PROTONS across the inner mitochondrial membrane.
Computer-based representation of physical systems and phenomena such as chemical processes.
Calcium-binding proteins that are found in DISTAL KIDNEY TUBULES, INTESTINES, BRAIN, and other tissues where they bind, buffer and transport cytoplasmic calcium. Calbindins possess a variable number of EF-HAND MOTIFS which contain calcium-binding sites. Some isoforms are regulated by VITAMIN D.
The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.
The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.
Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.
The point or frequency at which all flicker of an intermittent light stimulus disappears.
Application of statistical procedures to analyze specific observed or assumed facts from a particular study.
A neurotoxic isoxazole isolated from species of AMANITA. It is obtained by decarboxylation of IBOTENIC ACID. Muscimol is a potent agonist of GABA-A RECEPTORS and is used mainly as an experimental tool in animal and tissue studies.
A species of the genus MACACA which inhabits Malaya, Sumatra, and Borneo. It is one of the most arboreal species of Macaca. The tail is short and untwisted.
Continuous frequency distribution of infinite range. Its properties are as follows: 1, continuous, symmetrical distribution with both tails extending to infinity; 2, arithmetic mean, mode, and median identical; and 3, shape completely determined by the mean and standard deviation.
Recording of the average amplitude of the resting potential arising between the cornea and the retina in light and dark adaptation as the eyes turn a standard distance to the right and the left. The increase in potential with light adaptation is used to evaluate the condition of the retinal pigment epithelium.
The ability to respond to segments of the perceptual experience rather than to the whole.
The process by which the nature and meaning of tactile stimuli are recognized and interpreted by the brain, such as realizing the characteristics or name of an object being touched.
Brain waves characterized by a relatively high voltage or amplitude and a frequency of 8-13 Hz. They constitute the majority of waves recorded by EEG registering the activity of the parietal and occipital lobes when the individual is awake, but relaxed with the eyes closed.
The ability to estimate periods of time lapsed or duration of time.
Those affective states which can be experienced and have arousing and motivational properties.
The observable response of a man or animal to a situation.
Loss of the ability to comprehend the meaning or recognize the importance of various forms of stimulation that cannot be attributed to impairment of a primary sensory modality. Tactile agnosia is characterized by an inability to perceive the shape and nature of an object by touch alone, despite unimpaired sensation to light touch, position, and other primary sensory modalities.
General term for a number of inherited defects of amino acid metabolism in which there is a deficiency or absence of pigment in the eyes, skin, or hair.
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
Therapeutic introduction of ions of soluble salts into tissues by means of electric current. In medical literature it is commonly used to indicate the process of increasing the penetration of drugs into surface tissues by the application of electric current. It has nothing to do with ION EXCHANGE; AIR IONIZATION nor PHONOPHORESIS, none of which requires current.
Artificial device such as an externally-worn camera attached to a stimulator on the RETINA, OPTIC NERVE, or VISUAL CORTEX, intended to restore or amplify vision.
Vision considered to be inferior to normal vision as represented by accepted standards of acuity, field of vision, or motility. Low vision generally refers to visual disorders that are caused by diseases that cannot be corrected by refraction (e.g., MACULAR DEGENERATION; RETINITIS PIGMENTOSA; DIABETIC RETINOPATHY, etc.).

Vision: modular analysis--or not? (1/5702)

It has commonly been assumed that the many separate areas of the visual system perform modular analyses, each restricted to a single attribute of the image. A recent paper advocates a radically different approach, where all areas in the hierarchy analyse all attributes of the image to extract perceptually relevant decisions.  (+info)

On the neural correlates of visual perception. (2/5702)

Neurological findings suggest that the human striate cortex (V1) is an indispensable component of a neural substratum subserving static achromatic form perception in its own right and not simply as a central distributor of retinally derived information to extrastriate visual areas. This view is further supported by physiological evidence in primates that the finest-grained conjoined representation of spatial detail and retinotopic localization that underlies phenomenal visual experience for local brightness discriminations is selectively represented at cortical levels by the activity of certain neurons in V1. However, at first glance, support for these ideas would appear to be undermined by incontrovertible neurological evidence (visual hemineglect and the simultanagnosias) and recent psychophysical results on 'crowding' that confirm that activation of neurons in V1 may, at times, be insufficient to generate a percept. Moreover, a recent proposal suggests that neural correlates of visual awareness must project directly to those in executive space, thus automatically excluding V1 from a related perceptual space because V1 lacks such direct projections. Both sets of concerns are, however, resolved within the context of adaptive resonance theories. Recursive loops, linking the dorsal lateral geniculate nucleus (LGN) through successive cortical visual areas to the temporal lobe by means of a series of ascending and descending pathways, provide a neuronal substratum at each level within a modular framework for mutually consistent descriptions of sensory data. At steady state, such networks obviate the necessity that neural correlates of visual experience project directly to those in executive space because a neural phenomenal perceptual space subserving form vision is continuously updated by information from an object recognition space equivalent to that destined to reach executive space. Within this framework, activity in V1 may engender percepts that accompany figure-ground segregations only when dynamic incongruities are resolved both within and between ascending and descending streams. Synchronous neuronal activity on a short timescale within and across cortical areas, proposed and sometimes observed as perceptual correlates, may also serve as a marker that a steady state has been achieved, which, in turn, may be a requirement for the longer time constants that accompany the emergence and stability of perceptual states compared to the faster dynamics of adapting networks and the still faster dynamics of individual action potentials. Finally, the same consensus of neuronal activity across ascending and descending pathways linking multiple cortical areas that in anatomic sequence subserve phenomenal visual experiences and object recognition may underlie the normal unity of conscious experience.  (+info)

Transient and permanent deficits in motion perception after lesions of cortical areas MT and MST in the macaque monkey. (3/5702)

We examined the nature and the selectivity of the motion deficits produced by lesions of extrastriate areas MT and MST. Lesions were made by injecting ibotenic acid into the representation of the left visual field in two macaque monkeys. The monkeys discriminated two stimuli that differed either in stimulus direction or orientation. Direction and orientation discrimination were assessed by measuring thresholds with gratings and random-dots placed in the intact or lesioned visual fields. At the start of behavioral testing, we found pronounced, motion-specific deficits in thresholds for all types of moving stimuli, including pronounced elevations in contrast thresholds and in signal-to-noise thresholds measured with moving gratings, as well as deficits in direction range thresholds and motion coherence measured with random-dot stimuli. In addition, the accuracy of direction discrimination was reduced at smaller spatial displacements (i.e. step sizes), suggesting an increase in spatial scale of the residual directional mechanism. Subsequent improvements in thresholds were seen with all motion stimuli, as behavioral training progressed, and these improvements occurred only with extensive behavioral testing in the lesioned visual field. These improvements were particularly pronounced for stimuli not masked by noise. On the other hand, deficits in the ability to extract motion from noisy stimuli and in the accuracy of direction discrimination persisted despite extensive behavioral training. These results demonstrate the importance of areas MT and MST for the perception of motion direction, particularly in the presence of noise. In addition, they provide evidence for the importance of behavioral training for functional recovery after cortical lesions. The data also strongly support the idea of functional specialization of areas MT and MST for motion processing.  (+info)

Modulation of long-term synaptic depression in visual cortex by acetylcholine and norepinephrine. (4/5702)

In a slice preparation of rat visual cortex, we discovered that paired-pulse stimulation (PPS) elicits a form of homosynaptic long-term depression (LTD) in the superficial layers when carbachol (CCh) or norepinephrine (NE) is applied concurrently. PPS by itself, or CCh and NE in the absence of synaptic stimulation, produced no lasting change. The LTD induced by PPS in the presence of NE or CCh is of comparable magnitude with that obtained with prolonged low-frequency stimulation (LFS) but requires far fewer stimulation pulses (40 vs 900). The cholinergic facilitation of LTD was blocked by atropine and pirenzepine, suggesting involvement of M1 receptors. The noradrenergic facilitation of LTD was blocked by urapidil and was mimicked by methoxamine, suggesting involvement of alpha1 receptors. beta receptor agonists and antagonists were without effect. Induction of LTD by PPS was inhibited by NMDA receptor blockers (completely in the case of NE; partially in the case of CCh), suggesting that one action of the modulators is to control the gain of NMDA receptor-dependent homosynaptic LTD in visual cortex. We propose that this is a mechanism by which cholinergic and noradrenergic inputs to the neocortex modulate naturally occurring receptive field plasticity.  (+info)

Competitive mechanisms subserve attention in macaque areas V2 and V4. (5/5702)

It is well established that attention modulates visual processing in extrastriate cortex. However, the underlying neural mechanisms are unknown. A consistent observation is that attention has its greatest impact on neuronal responses when multiple stimuli appear together within a cell's receptive field. One way to explain this is to assume that multiple stimuli activate competing populations of neurons and that attention biases this competition in favor of the attended stimulus. In the absence of competing stimuli, there is no competition to be resolved. Accordingly, attention has a more limited effect on the neuronal response to a single stimulus. To test this interpretation, we measured the responses of neurons in macaque areas V2 and V4 using a behavioral paradigm that allowed us to isolate automatic sensory processing mechanisms from attentional effects. First, we measured each cell's response to a single stimulus presented alone inside the receptive field or paired with a second receptive field stimulus, while the monkey attended to a location outside the receptive field. Adding the second stimulus typically caused the neuron's response to move toward the response that was elicited by the second stimulus alone. Then, we directed the monkey's attention to one element of the pair. This drove the neuron's response toward the response elicited when the attended stimulus appeared alone. These findings are consistent with the idea that attention biases competitive interactions among neurons, causing them to respond primarily to the attended stimulus. A quantitative neural model of attention is proposed to account for these results.  (+info)

CRE-mediated gene transcription in neocortical neuronal plasticity during the developmental critical period. (6/5702)

Neuronal activity-dependent processes are believed to mediate the formation of synaptic connections during neocortical development, but the underlying intracellular mechanisms are not known. In the visual system, altering the pattern of visually driven neuronal activity by monocular deprivation induces cortical synaptic rearrangement during a postnatal developmental window, the critical period. Here, using transgenic mice carrying a CRE-lacZ reporter, we demonstrate that a calcium- and cAMP-regulated signaling pathway is activated following monocular deprivation. We find that monocular deprivation leads to an induction of CRE-mediated lacZ expression in the visual cortex preceding the onset of physiologic plasticity, and this induction is dramatically downregulated following the end of the critical period. These results suggest that CRE-dependent coordinate regulation of a network of genes may control physiologic plasticity during postnatal neocortical development.  (+info)

MST neuronal responses to heading direction during pursuit eye movements. (7/5702)

As you move through the environment, you see a radial pattern of visual motion with a focus of expansion (FOE) that indicates your heading direction. When self-movement is combined with smooth pursuit eye movements, the turning of the eye distorts the retinal image of the FOE but somehow you still can perceive heading. We studied neurons in the medial superior temporal area (MST) of monkey visual cortex, recording responses to FOE stimuli presented during fixation and smooth pursuit eye movements. Almost all neurons showed significant changes in their FOE selective responses during pursuit eye movements. However, the vector average of all the neuronal responses indicated the direction of the FOE during both fixation and pursuit. Furthermore, the amplitude of the net vector increased with increasing FOE eccentricity. We conclude that neuronal population encoding in MST might contribute to pursuit-tolerant heading perception.  (+info)

Retinotopic mapping of lateral geniculate nucleus in humans using functional magnetic resonance imaging. (8/5702)

Subcortical nuclei in the thalamus, which play an important role in many functions of the human brain, provide challenging targets for functional mapping with neuroimaging techniques because of their small sizes and deep locations. In this study, we explore the capability of high-resolution functional magnetic resonance imaging at 4 Tesla for mapping the retinotopic organization in the lateral geniculate nucleus (LGN). Our results show that the hemifield visual stimulation only activates LGN in the contralateral hemisphere, and the lower-field and upper-field visual stimulations activate the superior and inferior portion of LGN, respectively. These results reveal a similar retinotopic organization between the human and nonhuman primate LGN and between LGN and the primary visual cortex. We conclude that high-resolution functional magnetic resonance imaging is capable of functional mapping of suborganizations in small nuclei together with cortical activation. This will have an impact for studying the thalamocortical networks in the human brain.  (+info)

ABSTRACT. Aging often results in reduced visual acuity from changes in both the eye and neural circuits [1-4]. In normally aging subjects, primary visual cortex has been shown to have reduced responses to visual stimulation [5]. It is not known, however, to what extent aging affects visual field representations and population receptive sizes in human primary visual cortex. Here we use functional MRI (fMRI) and population receptive field (pRF) modeling [6] to measure angular and eccentric retinotopic representations and population receptive fields in primary visual cortex in healthy aging subjects ages 57 - 70 and in healthy young volunteers ages 24 - 36 (n = 9). Retinotopic stimuli consisted of black and white, drifting checkerboards comprising moving bars 11 deg in radius. Primary visual cortex (V1) was clearly identifiable along the calcarine sulcus in all hemispheres. There was a significant decrease in the surface area of V1 from 0 to 3 deg eccentricity in the aging subjects with respect to ...
Aging often results in reduced visual acuity from changes in both the eye and neural circuits [1-4]. In normally aging subjects, primary visual cortex has been shown to have reduced responses to visual stimulation [5]. It is not known, however, to what extent aging affects visual field repre-sentations and population receptive sizes in human primary visual cortex. Here we use func-tional MRI (fMRI) and population receptive field (pRF) modeling [6] to measure angular and ec-centric retinotopic representations and population receptive fields in primary visual cortex in healthy aging subjects ages 57 - 70 and in healthy young volunteers ages 24 - 36 (n = 9). Retinotopic stimuli consisted of black and white, drifting checkerboards comprising moving bars 11 deg in radius. Primary visual cortex (V1) was clearly identifiable along the calcarine sulcus in all hemispheres. There was a significant decrease in the surface area of V1 from 0 to 3 deg eccentricity in the aging subjects with respect to the young
TY - JOUR. T1 - Dynamics of orientation tuning in macaque primary visual cortex. AU - Ringach, Dario L.. AU - Hawken, Michael J.. AU - Shapley, Robert. PY - 1997/5/15. Y1 - 1997/5/15. N2 - Orientation tuning of neurons is one of the chief emergent characteristics of the primary visual cortex, VI. Neurons of the lateral geniculate nucleus, which comprise the thalamic input to V1, are not orientation-tuned, but the majority of V1 neurons are quite selective. How orientation tuning arises within VI is still controversial. To study this problem, we measured how the orientation tuning of neurons evolves with time 20 using a new method: reverse correlation in the orientation domain. Orientation tuning develops after a delay of 30-45 milliseconds and persists for 40-85 ms. Neurons in layers 4Cα or 4Cβ, which receive direct input from the thalamus, show a single orientation preference which remains unchanged throughout the response period. In contrast, the preferred orientations of output layer ...
In two experiments, magnetoencephalography (MEG) was used to investigate the effects of motion on gamma oscillations in human early visual cortex. When presented centrally, but not peripherally, stationary and moving gratings elicited several evoked and induced response components in early visual cortex. Time-frequency analysis revealed two nonphase locked gamma power increases-an initial, rapidly adapting response and one sustained throughout stimulus presentation and varying in frequency across observers from 28 to 64 Hz. Stimulus motion raised the sustained gamma oscillation frequency by a mean of approximately 10 Hz. The largest motion-induced frequency increases were in those observers with the lowest gamma response frequencies for stationary stimuli, suggesting a possible saturation mechanism. Moderate gamma amplitude increases to moving versus stationary stimuli were also observed but were not correlated with the magnitude of the frequency increase. At the same site in visual cortex, sustained
The cerebral cortex changes throughout the lifespan, and the cortical grey matter in many brain regions becomes thinner with advancing age. Effects of aging on cortical thickness have been observed in many brain regions, including areas involved in basic perceptual functions such as processing visual inputs. An important property of early visual cortices is their topographic organization - the cortical structure of early visual areas forms a topographic map of retinal inputs. Primary visual cortex (V1) is considered to be the most basic cortical area in the visual processing hierarchy, and is topographically organized from posterior (central visual representation) to anterior (peripheral visual representation) along the calcarine sulcus. Some studies have reported strong age-dependent cortical thinning in portions of V1 that likely correspond to peripheral visual representations, while there is less evidence of substantial cortical thinning in central V1. However, the effect of aging on cortical
Through massively parallel computational simulations, we studied how a large network of simple neural elements (the RF-LISSOM model) could develop a functional organization similar to that of the primary visual cortex. It was found that starting from a tabula rasa state, the afferent and lateral connections in the network self-organized cooperatively and simultaneously through a common Hebbian mechanism, and produced receptive fields (RFs), orientation maps, and patterns of lateral connections that follow the receptive field organization. Second, we hypothesized that similar self-organizing mechanisms continue operating in the adult cortex, maintaining it in a continuously-adapting dynamic equilibrium with the input, and tested this hypothesis on the self-organized model. When the equilibrium was perturbed by a retinal scotoma, RFs expanded in size in a reversible fashion, matching recent neurobiological observations in the cat and psychophysical experiments in the human. Third, a possible ...
The simple-cell receptive field (RF) structure is an attractive and unique feature of the primary visual cortex, which is thought to reflect the circuitry principles governing orientation selectivity. Synaptic inputs underlying spike RFs are key to understanding mechanisms for neuronal processing. The well-known push-pull model, which is proposed to explain the synaptic mechanism under simple-cell RFs, predicts that in simple cells the spatially separated excitation and inhibition does not interact with each other and that simple inhibitory neurons exist in the primary visual cortex (V1). However, previous experimental results suggest that synaptic inhibition plays an important role in shaping RF properties in the visual cortex. The synaptic mechanisms underlying simple-cell RFs remain not well understood, partly due to difficulties in systematically studying functional properties of cortical inhibitory neurons and precisely measuring excitatory and inhibitory synaptic inputs in vivo.; In the ...
In the visual system, prolonged exposure to a high contrast stimulus leads to a decrease in neuronal responsiveness, referred to as contrast adaptation. Contrast adaptation has been extensively studied in carnivores and primates, but has so far received little attention in mice. This thesis explores contrast adaptation and its mechanisms in mouse primary visual cortex (V1). Using extracellular tetrode recordings in mouse V1, I found contrast adaptation to be orientation unspecific. While this finding differs from reports in carnivores and primates, it is consistent with the notion that responsiveness of individual neurons is influenced by the activity history of the local network. Adaptation was also found to be cell-type specific, as putative parvalbumin (PV) expressing interneurons underwent less adaptation than other cell types. There is debate whether adaptation arises within the cortex or is inherited from the earlier stages in the visual pathway (e.g. visual thalamus or retina). In order ...
In this study, we have introduced optimal orientation as a benchmark for evaluating the performance of orientation strategies in given flow conditions. With optimal orientation, trajectories are longest yet travel duration is minimized by steering through regions of relatively high flow support. The illustrated trajectories (figures 1a,b and 2a,b) demonstrate that optimal orientation in horizontal flow does not always involve increased compensation on approach to the goal (cf. [12,13]), can involve either over-drift or over-compensation en route (cf. [23,38]) and is not always equivalent to full drift in balanced flows (contra [12]).. Our results provide insight into the value of information an animal may have about flow conditions. In flow that is weak compared to self-speeds (W ≤ 0.5), flow prediction is not essential as full compensation and goal orientation are all nearly as reliable and efficient as flow-adjusted vector orientation and optimal orientation (figures 1d, 2d and 3d). This ...
One of the most prominent characteristics of the human neocortex is its laminated structure. The first person to observe this was Francesco Gennari in the second half the 18th century: in the middle of the depth of primary visual cortex, myelinated fibres are so abundant that he could observe them
TY - JOUR. T1 - Large-scale remapping of visual cortex is absent in adult humans with macular degeneration. AU - Baseler, Heidi A.. AU - Gouws, Andre. AU - Haak, Koen V.. AU - Racey, Christopher. AU - Crossland, Michael D.. AU - Tufail, Adnan. AU - Rubin, Gary S.. AU - Cornelissen, Frans W.. AU - Morland, Antony B.. PY - 2011/5. Y1 - 2011/5. N2 - The occipital lobe contains retinotopic representations of the visual field. The representation of the central retina in early visual areas (V1-3) is found at the occipital pole. When the central retina is lesioned in both eyes by macular degeneration, this region of visual cortex at the occipital pole is accordingly deprived of input. However, even when such lesions occur in adulthood, some visually driven activity in and around the occipital pole can be observed. It has been suggested that this activity is a result of remapping of this area so that it now responds to inputs from intact, peripheral retina. We evaluated whether or not remapping of ...
|jats:p| 1. Twenty-four patients with electrodes chronically implanted on the surface of extrastriate visual cortex viewed faces, equiluminant scrambled faces, cars, scrambled cars, and butterflies. 2. A surface-negative potential, N200, was evoked by faces but not by the other categories of stimuli. N200 was recorded only from small regions of the left and right fusiform and inferior temporal gyri. Electrical stimulation of the same region frequently produced a temporary inability to name familiar faces. 3. The results suggest that discrete regions of inferior extrastriate visual cortex, varying in location between individuals, are specialized for the recognition of faces. These face modules appear to be intercalated among other functionally specific small regions. |/jats:p|
This paper describes the performance of a neuronal network model of the input layer 4Cα of macaque V1. This model differs from others in the literature in several ways. (i) It is designed largely from data for the anatomy and physiology of layer 4Cα of macaque (i.e., length scales and patterning of connectivity, and pinwheel centers). (ii) It uses cortical coordinates rather than idealized coordinates as in ring models (7, 8, 28) or near-ring models (9), whose coordinate labels are angles of orientation preference, rather than cortical locations within the layer. (iii) It has only short-range local inhibition, which is consistent with anatomical data, rather than an inhibition which is explicitly long-range in orientation preference, as is standard for many models (7-9, 31). (iv) It uses membrane potential, driven by synaptic conductances, as the fundamental variables, rather than activities or mean firing rates (7, 8, 32), or a probabilistic population-density representation (31, 33, ...
Spike count correlations (SCCs), covariation of neuronal responses across multiple presentations of the same stimulus, are ubiquitous in sensory cortices and span different modalities (1⇓-3) and processing stages (4⇓⇓-7). In the visual system, SCCs, also termed noise correlations, have traditionally been considered to be independent of the stimulus and hence have been thought to impede stimulus encoding (8). Studies on stimulus-independent aspects of SCCs in the primary visual cortex (V1) sought to capture correlation patterns that were solely accounted for by differences in receptive field structure (9, 10). Initial investigations of dependence of SCCs on low-level stimulus features, such as orientation and contrast, focused on the population mean of SCCs (11⇓-13), but stimulus-dependent changes in the mean are modest in awake animals (9, 14). Only recently has orientation and contrast dependence of the fine structure of SCCs been demonstrated in anesthetized cats and awake mice (15). ...
Intracellular recordings from simple cells of the cat visual cortex were used to test linear models for the generation of selectivity for the direction of visual motion. Direction selectivity has been thought to arise in part from nonlinear processes, as suggested by previous experiments that were based on extracellular recordings of action potentials. In intracellular recordings, however, the fluctuations in membrane potential evoked by moving stimuli were accurately predicted by the linear summation of responses to stationary stimuli. Nonlinear mechanisms were not required. ...
The mechanisms of attention prioritize sensory input for efficient perceptual processing. Influential theories suggest that attentional biases are mediated via preparatory activation of task-relevant perceptual representations in visual cortex, but the neural evidence for a preparatory coding model of attention remains incomplete. In this experiment, we tested core assumptions underlying a preparatory coding model for attentional bias. Exploiting multivoxel pattern analysis of functional neuroimaging data obtained during a non-spatial attention task, we examined the locus, time-course, and functional significance of shape-specific preparatory attention in the human brain. Following an attentional cue, yet before the onset of a visual target, we observed selective activation of target-specific neural subpopulations within shape-processing visual cortex (lateral occipital complex). Target-specific modulation of baseline activity was sustained throughout the duration of the attention trial and the degree
Orientation and ocular dominance maps in the primary visual cortex of mammals are among the most thoroughly investigated of the patterns in the cerebral cortex. A considerable amount of work has been dedicated to unraveling both their detailed structure and the neural mechanisms that underlie their formation and development. Many schemes have been proposed, some of which are in competition. Some models focus on development of receptive fields while others focus on the structure of cortical maps, i.e., the arrangement of receptive field properties across the cortex. Each model used different means to determine its success at reproducing experimental map patterns, often relying principally on visual comparison. Experimental data are becoming available that allow a more careful evaluation of models. In this contribution more than 10 of the most prominent models of cortical map formation and structure are critically evaluated and compared with the most recent experimental findings from macaque ...
Our results provide the first evidence that temporal expectation modulates the power and coherence of gamma responses already at the earliest stage of cortical visual processing. It has been shown that the power and synchronization of gamma oscillations can be modulated by spatial and feature selective attention (Müller et al., 2000; Fries et al., 2001, 2008; Bichot et al., 2005; Taylor et al., 2005; Buschman and Miller, 2007). Our findings extend this notion to the temporal domain.. Fries et al. (2001, 2008) found that gamma synchronization in area V4 was stronger when attention was directed to a stimulus inside the RF. The expectation effects we found in V1 are of comparable magnitude as those found for spatial attention in V4. However, the effects of expectation in V1 are not confined to the attended location (here the fixation point), since the modulation in gamma was comparable for sites recorded simultaneously in the central and peripheral representations of the visual field. These ...
r norman ,rsnorman_ at, wrote in message news:,cqqpbvgsktmgosm9sad08spq7l868a7929 at,... , On 9 May 2003 20:05:58 -0700, peer-error at (External Network , Error) wrote: , , ,Hi: , , , ,I am planning on developing a digital/brain interface. It uses FSK , ,[Frequency Shift Keying] signals. It is in a silicon-chip. This , ,silicon-chip is attached to a subjects visual cortex [chips , ,circuits connected to visual cortexs neurons]. The chip processes , ,FSK. The chip has information about the subjects visual cortex. In , ,order to produce the correct visual perception, it has to: , , , ,1. Convert to FSK information to a language the visual cortex can , ,understand , ,2. Excite the correct region[s] of the visual cortex with the , ,compatible language. , , , ,My design acts by affecting negative neuronal ions in the visual , ,cortex with electrons. The digital electric signal is initially , ,FSK-modulated. This signals format is then altered so that it can , ...
The neural basis of visual perception can be understood only when the sequence of cortical activity underlying successful recognition is known. The early steps in this processing chain, from retina to the primary visual cortex, are highly local, and the perception of more complex shapes requires integration of the local information. In Study I of this thesis, the progression from local to global visual analysis was assessed by recording cortical magnetoencephalographic (MEG) responses to arrays of elements that either did or did not form global contours. The results demonstrated two spatially and temporally distinct stages of processing: The first, emerging 70 ms after stimulus onset around the calcarine sulcus, was sensitive to local features only, whereas the second, starting at 130 ms across the occipital and posterior parietal cortices, reflected the global configuration. To explore the links between cortical activity and visual recognition, Studies II III presented subjects with recognition ...
In the past two decades, sensory neuroscience has moved from describing response properties to external stimuli in cerebral cortex to establishing connections between neuronal activity and sensory perception. The seminal studies by Newsome, Movshon and colleagues in the awake behaving macaque firmly link single cells in extrastriate area V5/MT and perception of motion. A decade later, extrastriate visual cortex appears awash with neuronal correlates for many different perceptual tasks. Examples are attentional signals, choice signals for ambiguous images, correlates for binocular rivalry, stereo and shape perception, and so on. These diverse paradigms are aimed at elucidating the neuronal code for perceptual processes, but it has been little studied how they directly compare or even interact. In this paper, I explore to what degree the measured neuronal signals in V5/MT for choice and attentional paradigms might reflect a common neuronal mechanism for visual perception.
Positron-emission tomography (PET) can localize functions of the human brain by imaging regional cerebral blood flow (CBF) during voluntary behaviour. Functional brain mapping with PET, however, has been hindered by PETs poor spatial resolution (typically ,1 cm). We have developed an image-analysis strategy that can map functional zones not resolved by conventional PET images. Brain areas selectively activated by a behavioural task can be isolated by subtracting a paired control-state image from the task-state image, thereby removing areas not recruited by the task. When imaged in isolation the centre of an activated area can be located very precisely. This allows subtle shifts in response locale due to changes in task to be detected readily despite poor spatial resolution. As an initial application of this strategy we mapped the retinal projection topography of human primary visual cortex. Functional zones separated by less than 3 mm (centre-to-centre) were differentiated using PET CBF images ...
The local orientation structure of a visual image is fundamental to the perception of spatial form. Reports of reliable orientation-selective modulations in the pattern of fMRI activity have demonstrated the potential for investigating the representation of orientation in the human visual cortex. Or …
The striation of a stimulus passing across a complex or supercomplex receptive field of a cats visual cortex (RFVC) defines the characteristics of the fields responses. For each RF (receptive field) an optimum stimulus which evokes a maximum response can be found. The more bands there are in the optimum stimulus, the smaller is the average width of bars and the intervals between them. The effective areas of the stimulus is independent of the number of bands it contains and is equal to 2.6 degrees on the average (in diameter). The column of neurons with identical orientation of the RFs contains fields in which optimum stimuli consist of a different number of bands. These data lead one to assume that the RFVC are narrow-band filters of spatial frequencies and perform a piecewise Fourier transform of the image. A network of such neurons will discern the boundary between textures.*Cerebral cortex
The first stage of visual processing in the cortex is called V1. In primates, V1 creates a saliency map (highlights what is important) from visual inputs to guide the shifts of attention known as gaze shifts.[13] It does so by transforming visual inputs to neural firing rates from millions of neurons, such that the visual location signalled by the highest firing neuron is the most salient location to attract gaze shift. V1s firing rates are received by the superior colliculus (in the mid-brain) which reads out the V1 activities to guide gaze shifts. V1 has a very well-defined map of the spatial information in vision. For example, in humans, the upper bank of the calcarine sulcus (in the occipital lobe) responds strongly to the lower half of visual field (below the center), and the lower bank of the calcarine to the upper half of visual field. In concept, this retinotopic mapping is a transformation of the visual image from retina to V1. The correspondence between a given location in V1 and in ...
Author Summary How can humans and animals make complex decisions on time scales as short as 100 ms? The information required for such decisions is coded in neural activity and should be read out on a very brief time scale. Traditional approaches to coding of neural information rely on the number of electrical pulses, or spikes, that neurons fire in a certain time window. Although this type of code is likely to be used by the brain for higher cognitive tasks, it may be too slow for fast decisions. Here, we explore an alternative code which is based on the latency of spikes with respect to a reference signal. By analyzing the simultaneous responses of many cells in monkey visual cortex, we show that information about the orientation of visual stimuli can be extracted reliably from spike latencies on very short time scales.
Author: von Pföstl, V et al.; Genre: Poster; Published in Print: 2010-11; Title: Effects of lactate on primary visual cortex of non-human primates investigated by pharmaco mri and neurochemical analysis
TY - JOUR. T1 - Rapid, experience-dependent expression of synaptic NMDA receptors in visual cortex in vivo. AU - Quinlan, Elizabeth M.. AU - Philpot, Benjamin D.. AU - Huganir, Richard L.. AU - Bear, Mark F.. PY - 1999/4/1. Y1 - 1999/4/1. N2 - Sensory experience is crucial in the refinement of synaptic connections in the brain during development. It has been suggested that some forms of experience-dependent synaptic plasticity in vivo are associated with changes in the complement of postsynaptic glutamate receptors, although direct evidence has been lacking. Here we show that visual experience triggers the rapid synaptic insertion of new NMDA receptors in visual cortex. The new receptors have a higher proportion of NR2A subunits and, as a consequence, different functional properties. This effect of experience requires NMDA receptor activation and protein synthesis. Thus, rapid regulation of post- synaptic glutamate receptors is one mechanism for developmental plasticity in the brain. Changes in ...
Even when the primary visual cortical area is absent bilaterally from early life, the rest of a primate visual brain can develop and function normally to support day-to-day visual behaviour.
While recent studies of synaptic stability in adult cerebral cortex have focused on dendrites, how much axons change is unknown. We have used advances in axon labeling by viruses and in vivo two-photon microscopy to investigate axon branching and bouton dynamics in primary visual cortex (V1) of adul …
In this study, we show that top-down control mechanisms engaged during visual imagery of simple shapes (letters X and O) can selectively activate position-invariant perceptual codes in visual areas specialised for shape processing, including lateral occipital complex (LOC). First, we used multivoxel pattern analysis (MVPA) to identify visual cortical areas that code for shape within a position-invariant reference frame. Next, we examined the similarity between these high-level visual codes and patterns elicited while participants imagined the corresponding stimulus at central fixation. Our results demonstrate that imagery engages object-centred codes in higher-level visual areas. More generally, our results also demonstrate that top-down control mechanisms are able to generate highly specific patterns of visual activity in the absence of corresponding sensory input. We argue that a general model of top-down control must account for dynamic modulation of functional connectivity between high-level control
Macular degeneration (MD) causes lesions to the center of the retina. There is no cure for MD but several promising treatments aimed at restoring retinal lesions are under investigation. These restorative treatments, however, rely on the assumption that the patients brain can still process the retinal signals once they are restored. Whether this assumption is correct has yet to be determined. In previous work, we already established that the early visual cortex in MD does not reallocate its resources to processing the intact peripheral visual field (Baseler et al. 2011, Nature Neuroscience 14: 649-655), but it is still possible that long-term visual deprivation leads to visual cortical degeneration (Boucard et al. 2009, Brain 132: 1898-1906). Here, we used functional magnetic resonance imaging (fMRI) and a new fMRI data-analysis tool - connective field modeling (Haak et al. 2012, NeuroImage 66: 376-384) - to evaluate the retinotopic organization of the cortical lesion projection zone (LPZ) in 8 ...
We generated probabilistic area maps and maximum probability maps (MPMs) for a set of 18 retinotopic areas previously mapped in individual subjects (Georgieva et al., 2009 and Kolster et al., 2010) using four different inter-subject registration methods. The best results were obtained using a recently developed multimodal surface matching method. The best set of MPMs had relatively smooth borders between visual areas and group average area sizes that matched the typical size in individual subjects. Comparisons between retinotopic areas and maps of estimated cortical myelin content revealed the following correspondences: (i) areas V1, V2, and V3 are heavily myelinated; (ii) the MT cluster is heavily myelinated, with a peak near the MT/pMSTv border; (iii) a dorsal myelin density peak corresponds to area V3D; (iv) the phPIT cluster is lightly myelinated; and (v) myelin density differs across the four areas of the V3A complex. Comparison of the retinotopic MPM with cytoarchitectonic areas, including those
Purpose: : To understand the functional organization of murine visual cortex. Methods: : Single cell impulses are detected by inserting a metal micro-electrode through the dura-covered visual cortex of ketamine/xylazine anesthetized C57/Bl 6 mice, sometimes from two areas simultaneously. The retina of the left or right eye is stimulated with light emitting diodes (370, strong for UV cone opsin; 505 nm, strong for M cone opsin) producing full field stimuli. Eyes are light adapted to suppress rods. Evidence that more than one cone mechanism produces a response is based on selective chromatic adaptation or lack of response univariance; i.e. a response from one cone mechanism to different wavelengths becomes identical at an appropriate energy. Results: : Full field stimuli produce similar responses in all areas of V1, a negative/positive potential with single cell impulses, often of large amplitude. The response is detected at 0.3-0.5 mm below the cortical surface with a latency of about 50 ms. Most ...
Nauhaus, I.*, Nielsen, K.J.*, Disney, A.A., Callaway, E.M. (In press) Orthogonal micro-organization of orientation and spatial frequency in primate primary visual cortex. Nature Neuroscience.. Li Y., Aimone, J.B., Xu, X., Callaway, E.M., Gage, F.H. (2012) Development of GABAergic inputs controls the contribution of maturing neurons to the adult hippocampal network. Proceedings of the National Academy of Sciences 109(11):4290-4295.. Marshel, J.H., Garrett, M.E., Nauhaus, I., Callaway, E.M. (2011) Functional specialization of seven mouse visual cortical areas. Neuron 72(6):1040-1054.. Nauhaus, I., Nielsen, K.J., Callaway, E.M. (2012) Nonlinearity of two-photon Ca2+ imaging yields distorted measurements of tuning for V1 neuronal populations. Journal of Neurophysiology 107(3):923-936.. Nielsen, K.J., Callaway, E.M., Krauzlis, R.J. (2012) Viral vector-based reversible neuronal inactivation and behavioral manipulation in the macaque monkey. Frontiers in Systems Neuroscience 6(48).. Vivar, C., Potter, ...
Our data show that autoregulation in the PCA territory is altered by metabolic activation by eye opening in healthy older adult subjects. As we hypothesized, during eyes open, the PCA vascular bed is vasodilated and BFV is increased to meet the increased neuronal metabolic demand of the visual cortex. In this state, PCA is more vulnerable to blood pressure fluctuations as compared to the MCA territory, as reflected by the higher PCA transfer functions gains in the low-frequency (autoregulatory) range. However, when the eyes are closed and the visual cortex is in a metabolically quiescent state, the PCA autoregulation may be even more effective than the MCA, as shown by the lower gains in the low and cardiac frequency range.. Higher PCA transfer function gains have been previously reported by Haubrich et al5 who studied 30 older adults (mean age, 65±10 years) without cerebrovascular disease or dysautonomia and showed higher gains in the PCA compared to the MCA. However, these subjects were ...
Comparison of the effects of dark rearing and binocular suture on development and plasticity of cat visual cortex. Brain Res. 1981 Sep 14; 220(2):255-67 ...
In the experiments, we presented a set of picture stimuli to a neuron and recorded a set of noisy responses. We used a regularized pseudoinverse method (see Materials and Methods) to estimate the receptive-field map that describes the linear portion of each response of the cells. This incorporates a simple a priori constraint: the sensitivity of the receptive-field estimate should change smoothly as a function of two-dimensional location within the receptive field (Eq. 8). This constraint reduces the noise in the receptive-field estimates, increasing the spatial resolution possible from the limited number of stimulus presentations.. Figure 4 compares receptive-field reconstructions and their two-dimensional Fourier spectra performed with reversed correlation and the regularized pseudoinverse methods. Fields are shown for three cells and five different values of the regularization parameter λ. This parameter balances the constraints of response prediction and smooth receptive fields. For most ...
Visual neurons respond selectively to specific features that become increasingly complex in their form and dynamics from the eyes to the cortex. Retinal neurons prefer localized flashing spots of light, primary visual cortical (V1) neurons moving bars, and those in higher cortical areas, such as middle temporal (MT) cortex, favor complex features like moving textures. Whether there are general computational principles behind this diversity of response properties remains unclear. To date, no single normative model has been able to account for the hierarchy of tuning to dynamic inputs along the visual pathway. Here we show that hierarchical application of temporal prediction - representing features that efficiently predict future sensory input from past sensory input - can explain how neuronal tuning properties, particularly those relating to motion, change from retina to higher visual cortex. This suggests that the brain may not have evolved to efficiently represent all incoming information, as implied
© 2019 The Author(s) 2019. Published by Oxford University Press. All rights reserved. The primate visual system contains myriad feedback projections from higher-to lower-order cortical areas, an architecture that has been implicated in the top-down modulation of early visual areas during working memory and attention. Here we tested the hypothesis that these feedback projections also modulate early visual cortical activity during the planning of visually guided actions. We show, across three separate human functional magnetic resonance imaging (fMRI) studies involving object-directed movements, that information related to the motor effector to be used (i.e., limb, eye) and action goal to be performed (i.e., grasp, reach) can be selectively decoded-prior to movement-from the retinotopic representation of the target object(s) in early visual cortex. We also find that during the planning of sequential actions involving objects in two different spatial locations, that motor-related information can be
In adults, certain regions of the brains visual cortex respond preferentially to specific types of input, such as faces or objects-but how and when those preferences arise has long puzzled neuroscientists.
If you have a question about this talk, please contact John Mollon.. The surface area of human primary visual cortex (V1) varies substantially between individuals for reasons that are unknown. However, such variability is typically ignored by the vast majority of studies focusing only on commonalities in perception and visual processing. In this talk, I will discuss our recent lines of investigations in which we instead used functional MRI and magnetoencephalography (MEG) to study the link between visual cortical architecture, neural response properties in the visual system and subjective perception.. This talk is part of the Craik Club series.. ...
The molecular basis for the decline in experience-dependent neural plasticity over age remains poorly understood. In visual cortex, the robust plasticity induced in juvenile mice by brief monocular deprivation during the critical period is abrogated by genetic deletion of Arc, an activity-dependent regulator of excitatory synaptic modification. Here, we report that augmenting Arc expression in adult mice prolongs juvenile-like plasticity in visual cortex, as assessed by recordings of ocular dominance (OD) plasticity in vivo. A distinguishing characteristic of juvenile OD plasticity is the weakening of deprived-eye responses, believed to be accounted for by the mechanisms of homosynaptic long-term depression (LTD). Accordingly, we also found increased LTD in visual cortex of adult mice with augmented Arc expression and impaired LTD in visual cortex of juvenile mice that lack Arc or have been treated in vivo with a protein synthesis inhibitor. Further, we found that although activity-dependent ...
There is a substantial number of studies investigating how the primate brain performs visual search tasks, often focusing on cortical structures (e.g., Bichot, Rossi, & Desimone, 2005, Chelazzi, Miller, Duncan, & Desimone, 1993). While it was speculated for some time that only animals with large a neocortex may have mechanisms of visual search, it now seems clear that a structure like a neocortex is not necessary for pop-out sensitivity. But what then are the minimal requirements? Clearly, the responses within the classical receptive field of neurons are not enough; there must also be interactions between cells beyond the classical receptive field. In fact, the saliency model of Li (2002) proposes that horizontal connections between neurons in V1 provide enough contextual information to mediate the saliency of a stimulus. In birds, such substrates may be found in the the avian visual Wulst, which resembles in many respects the mammalian visual cortex (Nieder & Wagner, 1999; Pettigrew & Konishi, ...
Visual area MT is a model of choice in primate neurophysiological and human imaging research of visual perception, due to its considerable sensitivity to moving stimuli and the strong direction selectivity of its neurons. While the location of MT(V5) in the non-human primate is easily identifiable based on gross anatomy and appears consistent between animals, this is less the case in human subjects. Functional localisation of human MT+ with moving stimuli can identify a group of motion-sensitive regions, but defining MT proper has proved more challenging. In this review we consider approaches to studying the cyto- and myleoarchitecture of this cortical area that may, in the future, allow identification of human MT in vivo based on anatomy.
Humans survive in environments that contain a vast quantity and variety of visual information. All items of perceived visual information must be represented within a limited number of brain networks. The human brain requires mechanisms for selecting only a relevant fraction of perceived information for more in-depth processing, where neural representations of that information may be actively maintained and utilized for goal-directed behavior. Object-based attention is crucial for goal-directed behavior and yet remains poorly understood. Thus, in the study we investigate how neural representations of visual object information are guided by selective attention. The magnitude of activation in human extrastriate cortex has been shown to be modulated by attention; however, object-based attention is not likely to be fully explained by a localized gain mechanism. Thus, we measured information coded in spatially distributed patterns of brain activity with fMRI while human participants performed a task ...
TY - JOUR. T1 - Morphological variation of layer III pyramidal neurones in the occipitotemporal pathway of the macaque monkey visual cortex. AU - Elston, Guy N.. AU - Rosa, Marcello G.P.. PY - 1998/5/28. Y1 - 1998/5/28. N2 - We compared the morphological characteristics of layer III pyramidal neurones in different visual areas of the occipitotemporal cortical stream, which processes information related to object recognition in the visual field (including shape, colour and texture). Pyramidal cells were intracellularly injected with Lucifer Yellow in cortical slices cut tangential to the cortical layers, allowing quantitative comparisons of dendritic field morphology, spine density and cell body size between the blobs and interblobs of the primary visual area (V1), the interstripe compartments of the second visual area (V2), the fourth visual area (V4) and cytoarchitectonic area TEO. We found that the tangential dimension of basal dendritic fields of layer III pyramidal neurones increases from ...
Dopaminergic pathway and primary visual cortex are involved in the freezing of gait in Parkinsons disease: a PET-CT study Yongtao Zhou,1 Junwu Zhao,1,2 Yaqin Hou,3 Yusheng Su,3 Piu Chan,1 Yuping Wang11The Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, Peoples Republic of China; 2The Nuclear Medicine Department, Xuanwu Hospital of Capital Medical University, Beijing, Peoples Republic of China; 3The Department of Neurology, Weihai Municipal Hospital, Shandong, Peoples Republic of ChinaBackground: Freezing of gait (FOG) could be partly alleviated by dopaminergic drugs but the mechanism still needs to be elucidated. The purpose of this study is to explore the mechanisms of FOG by vesicular monoamine transporter VMAT2 distribution with the 18,F-AV133 tracer and 18-fludeoxyglucose positron emission tomography-computed tomography (18,F-FDG PET-CT).Methods: Clinical material and PET-CT data were collected from 20 patients with FOG and 147 patients without FOG from November
Cortical circuits are sensitive to experience during well-defined intervals of early postnatal development called critical periods (1). After the critical period, plasticity is reduced or absent. Monocular deprivation (MD) is a classic model of experience-dependent plasticity. MD during the critical period results in a shift of ocular dominance (OD) of cortical neurons in favor of the nondeprived eye (2, 3). No OD shift is seen after MD in adult animals. The factors responsible for the cessation of OD plasticity in adults are only partially known. There is some evidence that the developmental increase in intracortical inhibition reduces plasticity and contributes to the termination of the critical period (4-6). However, other factors present in the adult visual cortex could stabilize synaptic connections and limit experience-dependent plasticity. CSPGs are attractive candidates for this role. CSPGs are components of the ECM that inhibit axonal sprouting and growth (7-9). Their adult pattern of ...
CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): this article we investigate to what extent the statistical properties of natural images can be used to understand the variation of receptive field properties of simple cells in the mammalian primary visual cortex. The receptive fields of simple cells have been studied extensively (e.g., Hubel & Wiesel 1968, DeValois et al. 1982a, DeAngelis et al. 1993): they are localised in space and time, have band-pass characteristics in the spatial and temporal frequency domains, are oriented, and are often sensitive to the direction of motion of a stimulus. Here we will concentrate on the spatial properties of simple cells. Several hypotheses as to the function of these cells have been proposed. As the cells preferentially respond to oriented edges or lines, they can be viewed as edge or line detectors. Their joint localisation in both the spatial domain and the spatial frequency domain has led to the suggestion that they mimic Gabor
Synaptic plasticity plays a key role in processes of learning and memory. Long-term potentiation (LTP) is a relatively stable enhancement of synaptic transmission following specific patterns of electrical stimulation. Some types of learning (e.g. motor learning, fear conditioning) result in LTP-like changes at synapses. However, no studies have examined LTP-like plasticity in the visual cortex as a result of visual discrimination learning. A visual discrimination task was used to examine changes in LTP in the primary visual cortex (V1) of adult rats. Rats were placed in a Y-shaped water maze and required to swim to one choice arm containing a hidden platform. Distinct visual cues indicated the presence (CS+) and absence (CS-) of the platform. Rats learned to reliably discriminate the visual cues to successfully navigate the maze. Control rats received the same procedure, but the visual cues did not have a predictive relation with the platform. Following training, trained, control, and ...
GENESIS Turtle Cortex Model README file ======================================= This is the large scale model of turtle visual cortex (the NGU model) described in: Nenadic, Z., Ghosh, B.K. and Ulinski. P. (2003) Propagating Waves in Visual Cortex: A Large Scale Model of Turtle Visual Cortex, J. Computational Neuroscience 14:161-184. and Nenadic, Z., Ghosh, B.K. and Ulinski. P. (2002) Modeling and Estimation Problems in the Turtle Visual Cortex, IEEE Trans. Bio-Med. Eng., 49:753-762 It is also described in considerable detail in the file TurtleVisCortex-descrip.pdf, which is included in this archive. This README file tells how to run the simulation with GENESIS. To run the simulation --------------------- 1. If you do not have the GENESIS simulator installed, download it from the GENESIS web site at It is available in source and binary versions for UNIX/Linux, MAC OSX, and Windows with Cygwin. Follow the installation instructions provided with the GENESIS ...
We report the application of Optical coherence tomography (OCT) for visualizing a one dimensional depth resolved functional structure of cat brain in vivo. The OCT system is based on the known fact that neural activation induces structural changes such as capillary dilation and cellular swelling. Detecting these changes as an amplitude change of the scattered light, an OCT signal reflecting neural activity i.e., fOCT (functional OCT) could be obtained. Experiments have been done to obtain a depth resolved stimulus-specific profile of activation in cat visual cortex. Our results in one dimension indicate that indeed an orientation dependent functional signal could be obtained. Further, we show that this depth resolved fOCT signal is well correlated with the stimulus dependent column determined by OISI. Based on the results, the smallest functional unit in depth, resolved by the proposed system is around 40 micrometers . We are extending our system to perform two dimensional functional imaging ...
TY - JOUR. T1 - Population receptive field shapes in early visual cortex are nearly circular. AU - Lerma-Usabiaga, Garikoitz. AU - Winawer, Jonathan. AU - Wandell, Brian A.. N1 - Funding Information: Received Dec. 3, 2020; revised Jan. 3, 2021; accepted Jan. 10, 2021. Author contributions: G.L.-U., J.W., and B.A.W. designed research; G.L.-U., J.W., and B.A.W. performed research; G.L.-U. analyzed data; G.L.-U., J.W., and B.A.W. wrote the paper. This work was supported by the European Unions Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant 795807 (to G.L.-U.) and by National Institutes of Health Grants EY027401, EY027964, and MH111417 (to J.W.). We thank E. Silson, C. Baker, and R. Reynolds. We also thank R. Reynolds for help with the AFNI software. The authors declare no competing financial interests. Correspondence should be addressed to Garikoitz Lerma-Usabiaga at [email protected] Copyright © 2021 the ...
Behavioral studies have reported reduced spatial attention in amblyopia, a developmental disorder of spatial vision. However, the neural populations in the visual cortex linked with these behavioral spatial attention deficits have not been identified. Here, we use functional MRI-informed electroencephalography source imaging to measure the effect of attention on neural population activity in the visual cortex of human adult strabismic amblyopes who were stereoblind. We show that compared with controls, the modulatory effects of selective visual attention on the input from the amblyopic eye are substantially reduced in the primary visual cortex (V1) as well as in extrastriate visual areas hV4 and hMT+. Degraded attentional modulation is also found in the normal-acuity fellow eye in areas hV4 and hMT+ but not in V1. These results provide electrophysiological evidence that abnormal binocular input during a developmental critical period may impact cortical connections between the visual cortex and ...
For years, neural activity in the brains visual cortex was thought to have only one job: to create visual perceptions. A new study by researchers at MITs Picower Institute for Learning and Memory shows that visual cortical activity can serve another purpose -- connecting visual experience with non-visual events.. The study, slated to appear in the March 17 issue of Science, implies that sensory parts of the brain may be able to accomplish more complex tasks than previously imagined, according to co-authors Marshall G. Shuler, MIT research affiliate, and Mark F. Bear, professor of brain and cognitive sciences. The findings have implications for understanding how our brains imbue sensory experience with behavioral meaning.. Electrodes were implanted in the visual cortex of adult rats. Initially, as expected, their neurons responded only to light. However, as the animal repeatedly experienced a light stimulus with the delivery of a drop of water, the neuronal activity changed. And in many cases, ...
The sensory recruitment model envisages visual working memory (VWM) as an emergent property that is encoded and maintained in sensory (visual) regions. The model implies that enhanced sensory-perceptual functions, as in synaesthesia, entail a dedicated VWM-system, showing reduced visual cortex activity as a result of neural specificity. By contrast, sensory-perceptual decline, as in old age, is expected to show enhanced visual cortex activity as a result of neural broadening. To test this model, young grapheme-color synaesthetes, older adults and young controls engaged in a delayed pair-associative retrieval and a delayed matching-to-sample task, consisting of achromatic fractal stimuli that do not induce synaesthesia. While a previous analysis of this dataset (Pfeifer et al., 2016) has focused on cued retrieval and recognition of pair-associates (i.e., long-term memory), the current study focuses on visual working memory and considers, for the first time, the crucial delay period in which no visual
The characterisation of the extravascular (EV) contribution to the blood oxygenation level-dependent (BOLD) effect is important for understanding the spatial specificity of BOLD contrast and for modelling approaches that aim to extract quantitative metabolic parameters from the BOLD signal. Using bipolar crusher gradients, total (b = 0 s/mm(2) ) and predominantly EV (b = 100 s/mm(2) ) gradient echo BOLD ΔR(2)* and signal changes (ΔS/S) in response to visual stimulation (flashing checkerboard; f = 8 Hz) were investigated sequentially (within | 3 h) at 1.5, 3.0 and 7.0 T in the same subgroup of healthy volunteers (n = 7) and at identical spatial resolutions (3.5 × 3.5 × 3.5 mm(3)). Total ΔR(2)* (z-score analysis) values were -0.61 ± 0.10 s(-1) (1.5 T), -0.74 ± 0.05 s(-1) (3.0 T) and -1.37 ± 0.12 s(-1) (7.0 T), whereas EV ΔR(2)* values were -0.28 ± 0.07 s(-1) (1.5 T), -0.52 ± 0.07 s(-1) (3.0 T) and -1.25 ± 0.11 s(-1) (7.0 T). Although EV ΔR(2)* increased linearly with field, as expected, it
The distribution of orientation-selective cells in the primary visual cortex has been found to reflect the first-order statistics of visual inputs, i.e. which orientations are most common during a critical period [1]. Similarly, some properties of the lateral connections between these cells have been found to reflect the second-order statistics of images, i.e. the coocurrence statistics of oriented edge elements, but the results have differed by species. Specifically, horizontal connections have been found to be elongated along the axis of preferred orientation in tree shrew [2] and owl monkey [3], but not in macaque [4]. It is unclear whether these results indicate genuine species differences, or perhaps differences in the visual environments in which these animals were raised. Here we analyse the effect of input statistics on lateral excitatory connectivity in a developmental model of primary visual cortex, by relating differences in co-occurence statistics of distinct image datasets, analysed ...
In the fetal and neonatal monkey, periodically organized regions of high activity of acetylcholinesterase were found in the visual cortical area V2 (Area 18). The acetylcholinesterase bands, like the thin and thick stripes of cytochrome oxidase, were found to run orthogonal to the area 17/18 border. During neonatal development these bands progressively narrow and finally disappear shortly after four months of age.
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Neocortical interneurons display great morphological and physiological variability and are ideally positioned to control circuit dynamics, although their exact role is still poorly understood. To better understand this diversity, we have performed a detailed anatomical and physiological characterization of 3 subtypes of visual cortex interneurons, isolated from transgenic mice which express green fluorescent protein in somatostatin, parvalburnin, and neuropeptide Y positive neurons. We find that these 3 groups of interneurons have systematic differences in dendritic and axonal morphologies and also characteristically differ in the frequencies, amplitude, and kinetics of the spontaneous excitatory and inhibitory synaptic currents they receive. Moreover, we detect a correlation between the kinetics of their synaptic inputs and quantitative aspects of their axonal arborizations. This suggests that different interneuron types could channel different temporal patterns of activity. Our results also ...
Research Interest Visual neurophysiology and perception. Publications Lopour Beth A, Tavassoli Abtine, Fried Itzhak, Ringach Dario L Coding of information in the phase of local field potentials within human medial temporal lobe Neuron, 2013; 79(3): 594-606.. Paik Se-Bum, Ringach Dario L Link between orientation and retinotopic maps in primary visual cortex Proceedings of the National Academy of Sciences of the United States of America, 2012; 109(18): 7091-6.. Nauhaus Ian, Busse Laura, Ringach Dario L, Carandini Matteo Robustness of traveling waves in ongoing activity of visual cortex The Journal of neuroscience : the official journal of the Society for Neuroscience, 2012; 32(9): 3088-94.. Frey Jared, Ringach Dario L Binocular eye movements evoked by self-induced motion parallax The Journal of neuroscience : the official journal of the Society for Neuroscience, 2011; 31(47): 17069-73.. Paik Se-Bum, Ringach Dario L Retinal origin of orientation maps in visual cortex Nature neuroscience, 2011; ...
The calcarine fissure (or calcarine sulcus) is an anatomical landmark located at the caudal end of the medial surface of the brain. Its name comes from the Latin calcar meaning spur.. It is a complete sulcus. The calcarine sulcus begins near the occipital pole in two converging rami and runs forward to a point a little below the splenium of the corpus callosum, where it is joined at an acute angle by the medial part of the parietooccipital sulcus. The anterior part of this fissure gives rise to the prominence of the calcar avis in the posterior cornu of the lateral ventricle. The calcarine sulcus is where the primary visual cortex (V1) is concentrated. The central visual field is located in the posterior portion of the calcarine sulcus and the peripheral visual field in the anterior portion. ...
CiteSeerX - Scientific documents that cite the following paper: Antibody labeling of functional subdivisions in visual cortex: cat-301 immunoreactivity in striate and extrastriate cortex of the macaque. Vis Neurosci. 5:67--81
Matrix metalloproteinases play a crucial role in adult visual plasticity in the brains of healthy and stroke-affected mice and their activity has to be within a narrow window for experience-induced plasticity to occur.
Color perception in macaque monkeys and humans depends on the visually evoked activity in three cone photoreceptors and on neuronal post-processing of cone signals. Neuronal post-processing of cone signals occurs in two stages in the pathway from retina to the primary visual cortex. The first stage, in in P (midget) ganglion cells in the retina, is a single-opponent subtractive comparison of the cone signals. The single-opponent computation is then sent to neurons in the Parvocellular layers of the Lateral Geniculate Nucleus (LGN), the main visual nucleus of the thalamus. The second stage of processing of color-related signals is in the primary visual cortex, V1, where multiple comparisons of the single-opponent signals are made. The diversity of neuronal interactions in V1cortex causes the cortical color cells to be subdivided into classes of single-opponent cells and double-opponent cells. Double-opponent cells have visual properties that can be used to explain most of the phenomenology of color
Sensory experience has a profound influence in shaping the functional organization of the cerebral cortex. Over 30 years ago, Hubel and Wiesel described a critical period of postnatal development for the formation of binocular connections in cat visual cortex. They demonstrated that thisconnectivity can be dramatically altered by simple forms of sensory deprivation, such as the temporary closure of one eyelid (monoculardeprivation). Besides the obvious relevance of this neural plasticity to the development of visual capabilities in humans and animals, it seems likely hat similar processes form the basis for some forms of learning and memory in the adult brain. Indeed, visual cortical plasticity, like learning andmemory formation decreases with age and depend on the internal state of the animal. The research in this lab is directed toward elucidating thebasic mechanisms by which visual experience can modify cortical connections in the visual cortex, and how those mechanisms are regulated.. We ...
Home , Papers , Evidence of an increased neuronal activation-to-resting glucose uptake ratio in the visual cortex of migraine patients: a study comparing FDG-PET and visual evoked potentials. ...
Purpose: Patients with early onset retinal dysfunction have abnormal V1 fMRI responses when passively viewing a stimulus. In contrast, patients with adult onset dysfunction do not have significant V1 responses unless they are engaged in a demanding task (Masuda et al., 2008). The development of abnormal cortical responses appears to depend on the timing of the onset of retinal dysfunction. To measure the critical period for the development of abnormal V1 responses, we used fMRI in subjects with congenital, critical period onset, and adult onset macular degeneration (MD).. Methods: We recruited MD patients with similar central retinal lesions. The retinal damage deprives a zone in the posterior of V1 of its normal input projections. We refer to this as the lesion projection zone, LPZ. In the MD and healthy controls we used moving-bar stimuli and a model-based analytical method (Dumoulin and Wandell, 2008) to measure visual field maps and population receptive field (pRF) sizes. We made the ...
TY - JOUR. T1 - Subcellular Localization of Intercellular Adhesion Molecule-5 (Telencephalin) in the Visual Cortex Is Not Developmentally Regulated in the Absence of Matrix Metalloproteinase-9. AU - Kelly, Emily A.. AU - Tremblay, Marie-Eve. AU - Gahmberg, Carl G.. AU - Tian, Li. AU - Majewska, Ania K.. PY - 2014. Y1 - 2014. KW - ICAM-5. KW - dendrite. KW - electron microscopy. KW - plasticity. KW - telencephalin. KW - MMP-9. KW - LONG-TERM POTENTIATION. KW - MATRIX METALLOPROTEINASES. KW - MEMBRANE GLYCOPROTEIN. KW - NEURONAL GLYCOPROTEIN. KW - LEUKOCYTE ADHESION. KW - RAT HIPPOCAMPUS. KW - BRAIN. KW - EXPRESSION. KW - EPHA4. KW - MICROGLIA. KW - 1182 Biochemistry, cell and molecular biology. U2 - 10.1002/cne.23440. DO - 10.1002/cne.23440. M3 - Article. VL - 522. SP - 676. EP - 688. JO - Journal of Comparative Neurology. JF - Journal of Comparative Neurology. SN - 0021-9967. IS - 3. ER - ...
List of causes of Babinskis reflex and Lesions of the visual cortex in children, alternative diagnoses, rare causes, misdiagnoses, patient stories, and much more.
New research is challenging the long-held belief that stroke-induced blindness is untreatable and therefore permanent.. Though speech and motor impairments following stroke are routinely treated with great success, therapies for recovering vision have historically been thought impossible. Many stroke survivors have been consigned to permanent blindness as a result. Fortunately, a new study demonstrates that by stimulating healthy parts of the brain, vision recovery following a stroke is possible.. Krystel Huxlin, Ph.D., a neuroscientist and associate professor at the University of Rochester Eye Institute, helmed the study with seven stroke survivors of various ages who had all suffered severe damage to their primary visual cortex, an area of the brain responsible for making sense of visual stimuli so that a recognizable image can be perceived.. Primary visual cortex damage leaves stroke survivors with a vague awareness of visual stimuli but no way to make sense of what they are seeing or discern ...
Researchers at the Wellcome Trust Centre for Neuroimaging at UCL used non-invasive, real-time brain imaging that enabled participants to watch their own brain activity on a screen, a technique known as neurofeedback. During the training phase, they were asked to try to increase activity in the area of the brain that processes visual information, the visual cortex, by imagining images and observing how their brains responded.. After the training phase, the participants visual perception was tested using a new task that required them to detect very subtle changes in the contrast of an image. When they were asked to repeat this task while clamping brain activity in the visual cortex at high levels, those who had successfully learned to control their brain activity could improve their ability to detect even very small changes in contrast.. This improved performance was only observed when participants were exercising control over their brain activity.. Lead author Dr Frank Scharnowski, who is now ...
Our overarching interest is in the question of how experience and deprivation modify synaptic connections in the brain. Experience-dependent synaptic plasticity is the physical substrate of memory, sculpts connections during postnatal development to determine the capabilities and limitations of brain functions, is responsible for the reorganization of the brain after damage, and is vulnerable in numerous psychiatric and neurological diseases and contributes to their symptoms.. Historically, our major efforts to address this question have been focused on the visual cortex and hippocampus. The visual cortex is a site of robust experience-dependent synaptic plasticity, exemplified by the consequences of temporary monocular deprivation (MD) during childhood. MD sets in motion a stereotyped choreography of synaptic modification whereby the deprived-eye inputs to visual cortex rapidly lose strength and, with a delay, the open-eye inputs undergo a compensatory gain in strength. The behavioral ...
A key research direction in the lab examines visual cortex plasticity in blindness. In sighted primate, much of the occipital lobe is dedicated to visual perception. What happens to this part of the brain when it does not receive its species typical input during development? Previous research finds that in blindness, occipital areas are active during tactile and auditory tasks. One of our goals is to uncover the cognitive functions that are supported by the occipital cortex in blind people. Are these functions similar to vision? We find that in blindness visual areas become involved in higher-cognitive functions, including language, mathematical reasoning and non-verbal executive control. These functions recruit different parts of visual cortex within a single blind individuals. Studying the repurposing of visual cortex for higher-order cognition provides insights into the mechanisms that determine cortical specialization in humans. The lab is interested in how experience changes the ...
While the effects of visual deprivation have been well studied in animal models, much less is known about the effects of blindness on human early visual pathway...
Neuroscience research articles are provided.. What is neuroscience? Neuroscience is the scientific study of nervous systems. Neuroscience can involve research from many branches of science including those involving neurology, brain science, neurobiology, psychology, computer science, artificial intelligence, statistics, prosthetics, neuroimaging, engineering, medicine, physics, mathematics, pharmacology, electrophysiology, biology, robotics and technology. ...
A fundamental property of neuronal circuits is the ability to adapt to altered sensory inputs. It is well established that the functional synaptic changes underlying this adaptation are reflected by structural modifications in excitatory neurons. In contrast, the degree to which structural plasticity in inhibitory neurons accompanies functional changes is less clear. Here, we use two-photon imaging to monitor the fine structure of inhibitory neurons in mouse visual cortex after deprivation induced by retinal lesions. We find that a subset of inhibitory neurons carry dendritic spines, which form glutamatergic synapses. Removal of visual input correlates with a rapid and lasting reduction in the number of inhibitory cell spines. Similar to the effects seen for dendritic spines, the number of inhibitory neuron boutons dropped sharply after retinal lesions. Together, these data suggest that structural changes in inhibitory neurons may precede structural changes in excitatory circuitry, which ...
TY - JOUR. T1 - Attentional control of the processing of neutral and emotional stimuli. AU - Pessoa, Luiz. AU - Kastner, Sabine. AU - Ungerleider, Leslie G.. PY - 2002/12/1. Y1 - 2002/12/1. N2 - A typical scene contains many different objects that compete for neural representation due to the limited processing capacity of the visual system. At the neural level, competition among multiple stimuli is evidenced by the mutual suppression of their visually evoked responses and occurs most strongly at the level of the receptive field. The competition among multiple objects can be biased by both bottom-up sensory-driven mechanisms and top-down influences, such as selective attention. Functional brain imaging studies reveal that biasing signals due to selective attention can modulate neural activity in visual cortex not only in the presence but also in the absence of visual stimulation. Although the competition among stimuli for representation is ultimately resolved within visual cortex, the source of ...
The radial unit hypothesis provides a framework for global (proliferation) and regional (distribution) expansion of the primate cerebral cortex. Using principal component analysis (PCA), we have identified cortical regions with shared variance in their surface area and cortical thickness, respectively, segmented from magnetic resonance images obtained in 23,800 participants. We then carried out meta-analyses of genome-wide association studies of the first two principal components for each phenotype. For surface area (but not cortical thickness), we have detected strong associations between each of the components and single nucleotide polymorphisms in a number of gene loci. The first (global) component was associated mainly with loci on chromosome 17 (9.5e-32 ≤ p ≤ 2.8e-10), including those detected previously as linked with intracranial volume and/or general cognitive function. The second (regional) component captured shared variation in the surface area of the primary and adjacent secondary ...
Area 17 of the visual cortex was found to contain about 51,400 neurons per mm3. Area 17 is the primary visual cortex. Both ... Payne, B. R.; Siwek, D. F. (1991). "The Visual Map in the Corpus Callosum of the Cat". Cerebral Cortex. 1 (2): 173-88. doi: ... Without taurine, felines can have an abnormal morphology in the cerebellum and visual cortex. When cats were fed a diet ... "visual cortex". Farlex. Retrieved 22 May 2016. CS1 maint: discouraged parameter (link) "Gyrencephalic Definition". Serendip. ...
"Retinotopically defined primary visual cortex in Williams syndrome". Brain. 132 (3): 635-44. doi:10.1093/brain/awn362. PMC ... The parietal-dorsal area handles visual processing that supports visual-spatial analysis of the environment, while the ventral ... Increased volume and activation of the left auditory cortex has been observed in people with Williams syndrome, which has been ... Individuals with Williams syndrome have problems with visual processing, but this is related to difficulty in dealing with ...
Syken J, Grandpre T, Kanold PO, Shatz CJ (September 2006). "PirB restricts ocular-dominance plasticity in visual cortex". ... These results suggest PirB may be involved in modulation of synaptic plasticity in the visual cortex. ... PirB and visual plasticity[edit]. Paired-immunoglobulin-like receptor B (PirB), an MHCI-binding receptor, is involved in the ... regulation of visual plasticity.[5] PirB is expressed in the central nervous system and diminishes ocular dominance plasticity ...
Visual processing of the occluded stimulus begins in the primary visual cortex (V1), in the occipital lobe of the brain. V1 ... This is important in the visual system to aid in de-cluttering our visual environment, and interpreting information at a faster ... I-Perception, 9(4), 1-16 Lee, H., & Vecera, S. P. (2005). Visual cognition influences early vision: the role of visual short- ... It is one of the many functions of the visual system which aid in both seeing and understanding objects encountered on an ...
In extreme cases, the tau protein calcarine cortex, which contains the primary visual cortex in the brain. In the study, ... "Primary visual cortex , Radiology Reference Article ,". Radiopaedia. Retrieved 2019-03-18. Belson, Ken (2017-09 ... In stage I CTE, p-tau pathology can be observed in the cerebral cortex, most likely in the area between sulci. In the second ... In stage IV CTE, severe p-tau pathology is spread across all areas of the cerebral cortex and temporal lobe. ...
"Organization of high-level visual cortex in human infants". Nature Communications. 8: 13995. Bibcode:2017NatCo...813995D. doi: ... "Intact visual imagery and impaired visual perception in a patient with visual agnosia". J Exp Psychol Hum Percept Perform. 20 ( ... The fusiform face area - FFA (meaning: spindular/spindle-shaped face area) is a part of the human visual system that is ... "Cerebral Cortex. 15 (8): 1234-1242. doi:10.1093/cercor/bhi006. ISSN 1047-3211. PMID 15677350.. ...
For example, Bartels and Zeki have shown that different areas in the visual cortex specialize in processing the different ... "Synchrony and the binding problem in macaque visual cortex", Journal of Vision, 8 (7): 1-16, doi:10.1167/8.7.30, PMC 2647779, ... Lastly, by representing the hierarchical binding relationships between visual features at every spatial scale across a visual ... In the primary visual cortex, Dong et al. found that whether two neurons were responding to contours of the same shape or ...
Sonja Hansen (May 9, 2019). "Pokemon triggers visual cortex". 255 (53). The Stanford Daily. p. 1. Tobin, Joseph, ed. (February ... finding that seeing Pokémon stimulated activity in the visual cortex, in a different place than is triggered by recognizing ...
Jones B., and Anuza T. (1982). "Effects of sex, handedness, stimulus and visual field on "mental rotation"". Cortex. 18 (4): ... "Effects of Sex, Handedness, Stimulus and Visual Field on "Mental Rotation"". Cortex. 18 (4): 501-514. doi:10.1016/S0010-9452( ... A study at the University of California Santa Barbara was conducted to specifically test the extent to which visual information ... Mental rotation, as a function of visual representation in the human brain, has been associated with the right cerebral ...
... additional pathways within the brain connect to the visual cortex. ... Descending motor pathways of the pyramidal tracts travel from the cerebral cortex to the brainstem or lower spinal cord.[4][5] ... flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, ... Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles ...
... sensory signals from the eyes are transmitted to the thalamus and then to the primary visual cortex; inside the cerebral cortex ... Francis Crick and Christof Koch (1995). "Are we aware of neural activity in primary visual cortex?". Nature. 375 (6527): 121- ... it is possible for subjects to report a lack of awareness even when areas such as the primary visual cortex show clear ... "Surround modulation measured with functional MRI in the human visual cortex". Journal of Neurophysiology. 89 (1): 525-533. ...
The OVC was designed to work as a simulated visual cortex that has a critical job in processing and classify the objects to ... "How the Visual Cortex Recognizes". Poggio Lab., the Center for Biological & Computational Learning at the Massachusetts ... Human visual system model Visual system Machine Vision Image processing OpenCV Greenemeier, Larry (2008). "Visionary Research: ... and it's designed to give the researchers to experience the brain's visual cortex most close simulation for picture perception ...
Friday, 18 November 2011 Dani CooperABC (2011-11-18). "Synaesthesia sends visual cortex crazy". Retrieved 2020-02-12. ORCID. " ...
... schema of the visual map theory (1898). O=Optic chiasm; C=Visual (and motor) cortex; M, S=Decussating pathways; R, G: Sensory ... Ramón y Cajal, Santiago (1899). Comparative study of the sensory areas of the human cortex. Clark University. p. 85. Ramón y ... Camara lucida drawing of a Purkinje cell in the cat's cerebellar cortex, by Santiago Ramón y Cajal. List of pathologists " ... "Comparative study of the sensory areas of the human cortex" ...
"Synaptology of the visual cortex." Visual Centers in the Brain. Springer Berlin Heidelberg, 1973. 269-324. Kossuth Prize (1950 ... There he mainly addressed the cerebellum and functioning of the cerebral cortex. In addition, he performed experimental ...
In both the primary motor cortex and the visual cortex, the HDR amplitude scales linearly with duration of a stimulus or ... which relays visual inputs from the retina to the visual cortex, have been shown to generate the BOLD signal correctly when ... but evidence suggests a similar relationship at least for the auditory cortex and the primary visual cortex. Activation ... These signals get to the primary visual cortex via the thalamus in tens of milliseconds. Neuronal activity related to the act ...
... that if the damage to the visual cortex occurs in areas above the primary visual cortex the conscious awareness of visual ... Visual processing in the brain goes through a series of stages. Destruction of the primary visual cortex leads to blindness in ... Injury to the primary visual cortex, including lesions and other trauma, leads to the loss of visual experience.[57] However, ... Patients with blindsight have damage to the system that produces visual perception (the visual cortex of the brain and some of ...
Dikker, S. & Pylkkänen, L. (2011). Before the N400: Effects of lexical-semantic violations in visual cortex. Brain and Language ... Dikker, S., Rabagliati, H. & Pylkkänen, L. (2009). Sensitivity to syntax in visual cortex. Cognition, 110 (3), 293-321. ... The M100 discussed here is the magnetic equivalent of the visual N1 potential-an event-related potential linked to visual ... In the eyetracking visual world paradigm, experimental subjects listen to a sentence while staring at an array of pictures on a ...
In binocular neurons in the visual cortex, it is necessary to specify the corresponding area in both retinas (one in each eye ... In the case of binocular neurons in the visual cortex, receptive fields do not extend to optical infinity. Instead, they are ... Hubel and Wiesel (e.g., Hubel, 1963; Hubel-Wiesel 1959) classified receptive fields of cells in the visual cortex into simple ... It is also described how the receptive fields in the primary visual cortex, which are tuned to different sizes, orientations ...
"Language-specific tuning of visual cortex? Functional properties of the Visual Word Form Area". Brain. 125 (Pt 5): 1054-1069. ... Signal loss and response bias in visual and frontal cortex". Science. 360 (6388): 537-542. Bibcode:2018Sci...360..537V. doi: ... Dehaene S, Le Clec'H G, Poline JB, Le Bihan D, Cohen L (2002). "The visual word form area: a prelexical representation of ... McCandliss BD, Cohen L, Dehaene S (2003). "The visual word form area: expertise for reading in the fusiform gyrus". Trends in ...
149-152 MacEvoy, Sean; Michael A. Paradiso (14 March 2001). "Lightness constancy in primary visual cortex". PNAS. 98 (15): 8827 ... There are several types of perceptual constancies in visual perception: Size constancy is one type of visual subjective ... Visual auditory distance constancy - Researchers explored the relationship between visual and auditory responses and how they ... According to Kanwisher & associates, the localized part of the brain responsible for this is the extrastriate cortex. Color ...
Hubel & Wiesel discovered that neurons in the primary visual cortex, the first cortical area to process information coming from ... such as the Visual cortex, are understood in some detail.[31] It is also unknown what the computational functions of these ... binocular interaction and functional architecture in the cat's visual cortex". J. Physiol. 160 (1): 106-54. doi:10.1113/ ... "Interactions between frontal cortex and basal ganglia in working memory: A computational model" (PDF). doi: ...
"Superior parietal cortex activation during spatial attention shifts and visual feature conjunction". Science. 270 (5237): 802- ... Taves, E.H. (1941). "Two mechanisms for the perception of visual numerousness". Archives of Psychology. 37: 1-47.. ... Kaufman, E.L., Lord, M.W., Reese, T.W., & Volkmann, J. (1949). "The discrimination of visual number". American Journal of ... Atkinson, Campbell, and Francis[16] demonstrated that visual afterimages could be employed in order to achieve similar results ...
Todd JJ, Marois R (2004). "Capacity limit of visual short-term memory in human posterior parietal cortex". Nature. 428 (6984): ... The prefrontal cortex is made up of the anterior cingulate cortex, the intraparietal sulcus, the dorsolateral prefrontal cortex ... The anterior cingulate cortex has functions linked to motivation and emotion.[40] The intraparietal sulcus possesses functions ... Motivated forgetting occurs as a result of activity that occurs within the prefrontal cortex. This was discovered by testing ...
"Motility of Dendritic Spines in Visual Cortex in Vivo: Changes during the Critical Period and Effects of Visual Deprivation". ... They showed that columns in the primary visual cortex receiving inputs from the other eye took over the areas that would ... However, if one eye is patched, or otherwise prevented from receiving sensory input, the visual cortex will shift to favor ... Early in development, most of the visual cortex is binocular, meaning it receives roughly equal input from both eyes. Normally ...
The coordinated mapping of visual space and stimulus features in visual cortex. Neuron 47: 267-280, 2005. Tropea, D., G. ... which normally projects to the visual cortex, was induced to project to structures that normally process hearing. Visual input ... A map of visual space induced in primary auditory cortex. Science 250: 818-820, 1990. Hahm, J.-O., R.B. Langdon and M. Sur. ... Induction of visual orientation modules in auditory cortex. Nature 404: 841-847, 2000. Von Melchner, L., S.L. Pallas and M. Sur ...
Huk, Alexander C.; Heeger, David J. (2002-01-01). "Pattern-motion responses in human visual cortex". Nature Neuroscience. 5 (1 ... "Neural Activity in Macaque Parietal Cortex Reflects Temporal Integration of Visual Motion Signals during Perceptual Decision ... In his doctoral work, Huk used fMRI to map the human brain areas associated with visual motion processing. His postdoctoral ... He has made contributions towards understanding how the brain represents 3D visual motion and how those representations are ...
Archived 2007-12-03 at the Wayback Machine Hensch TK (2005). "Critical period mechanisms in developing visual cortex". Neural ...
Insular cortex Area 17 - Primary visual cortex (V1) Area 18 - Secondary visual cortex (V2) Area 19 - Associative visual cortex ... The primary visual cortex (Brodmann area 17), which is the main recipient of direct input from the visual part of the thalamus ... area 4 is the primary motor cortex; area 17 is the primary visual cortex; and areas 41 and 42 correspond closely to primary ... Brodmann area 17 is the primary visual cortex, and Brodmann area 25 is the anterior cingulate cortex. Many of those brain areas ...
HTM is also related to work by Tomaso Poggio, including an approach for modeling the ventral stream of the visual cortex known ... While HTM is mostly consistent with these ideas, it adds details about handling invariant representations in the visual cortex ... George, Dileep (2010-07-24). "Hierarchical Bayesian inference in the visual cortex". Archived from the ... "Hierarchical Bayesian Inference in the Visual Cortex". Journal of the Optical Society of America. A, Optics, Image Science, and ...
The prefrontal cortex is thought essential for all goal-directed and socially-mediated behavior. The PFC is an ideal target for ... The ratio of red/infrared light refraction is displayed as a visual signal on a computer monitor and may also be translated ... Most research in HEG has focused on disorders of the prefrontal cortex (PFC), the cortical region directly behind the forehead ... When a region of the cortex is used in a specific cognitive task, neuronal activity in that region increases, consequently ...
"Superior parietal cortex activation during spatial attention shifts and visual feature conjunction". Science. 270 (5237): 802- ... Kaufman, E.L.; Lord, M.W.; Reese, T.W. & Volkmann, J. (1949). "The discrimination of visual number". American Journal of ... Taves, E.H. (1941). "Two mechanisms for the perception of visual numerousness". Archives of Psychology. 37: 1-47.. ... Atkinson, Campbell, and Francis[16] demonstrated that visual afterimages could be employed in order to achieve similar results ...
Koenigs M, Young L, Adolphs R, Tranel D, Cushman F, Hauser M, Damasio A. (2007). «Damage to the prefrontal cortex increases ... Rapid interactions between the ventral visual stream and emotion-related structures rely on a two-pathway architecture» (PDF). ... Parvizi J, Van Hoesen G, Buckwalter J, Damasio A. (2006). «Neural connections of the posteromedial cortex in the macaque: ...
Talk:Accessory visual structures. *Talk:Accompanying artery of ischiadic nerve. *Talk:Acetabulum ... Talk:Adrenal cortex. *Talk:Adrenal medulla. *Talk:Adventitia. *Talk:Alar ligament. *Talk:Benjamin Alcock ...
A bilateral temporal visual field defect (due to compression of the optic chiasm) or dilation of the pupil, and the occurrence ... although glial cells outnumber neurons roughly 4 to 1 in the cerebral cortex. Glia come in several types, which perform a ... visual field impairment, impaired sense of smell, impaired hearing, facial paralysis, double vision, or more severe symptoms ... and poor spatial and visual perception.[citation needed] ...
For optics in the visual range, the amount of dispersion of a lens material is often quantified by the Abbe number:[29] ... a GRIN lens with a refractive index varying from about 1.406 in the inner core to approximately 1.386 at the less dense cortex. ... In the visual spectrum this is done using Zernike phase-contrast microscopy, differential interference contrast microscopy (DIC ...
Hof, Patrick R.; Van Der Gucht, Estel (2007). "Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae ( ... Whales do, however, lack short wavelength sensitive visual pigments in their cone cells indicating a more limited capacity for ...
... signals from S cones and there is evidence that they have a separate signal pathway through the thalamus to the visual cortex ... Visual Neuroscience. 20 (1): 11-17. doi:10.1017/s0952523803201024.. *^ Calderone, JB; Reese, BE; Jacobs, GH (2003). "Topography ... Ronald G. Boothe (2002). Perception of the visual environment. Springer. p. 219. ISBN 978-0-387-98790-3. .. ... These extra cone receptor visual pigments detect energy of other wavelengths, including sometimes ultraviolet. Eventually two ...
Multi-modal stimulation (MMS) includes the applications of auditory, tactile, vestibular, and visual stimulation that helps aid ... the rhythmic tapping of the left hand stimulates the right sensorimotor cortex in order to further engage the right hemisphere ... the therapist will introduce a visual stimuli of the written phrase to be learned.[46] The therapist then sings the phrase with ...
Arnott, S., Thaler, L., Milne, J., Kish, D., & Goodale, M. (n.d). Shape-specific activation of occipital cortex in an early ... Central visual acuity of 20/200 or less in the better eye with corrective glasses or central visual acuity of more than 20/200 ... Visual impairments may take many forms and be of varying degrees. Visual acuity alone is not always a good predictor of the ... Visual impairment has the ability to create consequences for health and well being. Visual impairment is increasing especially ...
Prefrontal cortex and the cognitive control of memory[edit]. Pars triangularis has been shown to have a role in cognitive ... Brodmann area 45 (BA45), is part of the frontal cortex in the human brain. It is situated on the lateral surface, inferior to ... 1999). "Effects of repetition and competition on activity of left prefrontal cortex during word generation". Neuron. 23 (3): ... This type of processing is directed, in part, by the ventrolateral prefrontal cortex (VLPFC). Pars triangularis is found in ...
Huettner, JE ja Baughman, RW, (1986). Primary culture of identified neurons from the visual cortex of postnatal rats. Journal ...
Faculty of 1000 evaluation for Visual cortex activity in early and late blind people.. F1000 - Post-publication peer review of ... 腦部不同位置如杏仁核、海馬體與vmPFC(英语:Ventromedial prefrontal cortex)在
cerebral cortex GABAergic interneuron migration. • glucose import. • visual learning. • sensitization. • positive regulation of ...
Cooke, Fred; Bruce, Jenni (2004). The Encyclopedia of Animals: a complete visual guide (1 ed.). Berkeley, California: ... Instead of using the cerebral cortex like mammals, birds use the mediorostral HVC for cognition.[74] Not only have parrots ... The head is large, with eyes positioned high and laterally in the skull, so the visual field of parrots is unlike any other ... Most parrots exhibit little or no sexual dimorphism in the visual spectrum. They form the most variably sized bird order in ...
In fMRI studies by Koutstaal the level of sensitivity of the right visual cortex with respect to the single exposure of an ... The left lateral orbitofrontal cortex and ventrolateral prefrontal cortex generate causal inferences and explanations of events ... However, when the image was only presented to the left visual field (which maps to the right brain hemisphere) the patients ... In these experiments when patients were shown an image within the right visual field (which maps to the left brain hemisphere ...
... most hallucinations are visual, they can encompass a broader range of sensory experience. Auditory hallucinations are thus also ... and the parts of the cortex related to our most complex logical-cognitive functions experience highly intense electrical ...
Role of right auditory cortex in fine pitch resolution[edit]. The primary auditory cortex is one of the main areas associated ... A system proposed to explain this understanding of actions is that visual representations of actions are mapped onto our own ... orbitofrontal cortex, ventral striatum, midbrain, and the ventral medial prefrontal cortex. Many of these areas appear to be ... Cereb". Cortex. 6: 102-119. doi:10.1093/cercor/6.2.102.. *^ Rizzolatti, G.; Luppino, G.; Matelli, M. (1998). "The organization ...
"for their discoveries relating to the هورمونs of the adrenal cortex, their structure and biological effects"[۴۹] ... "for their discoveries concerning the primary physiological and chemical visual processes in the eye"[۵۶] ...
మొదటి ఏడు ఎనిమిది సంవత్సరాల జీవితంలో, మెదడు దృష్ట్యాభివృద్ధి (visual development) అని పిలవబడే ప్రక్రియ ద్వారా కంటి నుండి వచ్చిన ... Tychsen, Lawrence (August 2012). "The Cause of Infantile Strabismus Lies Upstairs in the Cerebral Cortex, Not Downstairs in the ...
Cerebral cortices. *Visual cortex. *Auditory cortex. *Vestibular cortex. *Olfactory cortex. *Gustatory cortex ... The third-order neurons then send the signal to the somatosensory cortex. ...
... attention and visual engagement lead to Non-Instrumental Movement Inhibition.[76] One possible application for this phenomenon ... "Slow fluctuations in attentional control of sensory cortex". Journal of Cognitive Neuroscience. 23 (2): 460-470. doi:10.1162/ ... which are the movements of one's eyes to different visual stimuli. In an antisaccade task, for example, subjects with higher ... candidate neural mechanism for generating this aspect of experience is a network of regions in the frontal and parietal cortex ...
... posterior cingulate cortex, dorsal anterior cingulate cortex, and parts of the dorsomedial thalamus connecting to temporal and ... Specifically, the effect of losses is assumed to be on general attention rather than just visual or auditory attention. The ... This involves the ventral caudate nucleus, pallidum, putamen, bilateral orbitofrontal cortex, superior frontal and middle gyri ... Gehring, W.J.; Willoughby, A.R (2002). "The medial frontal cortex and the rapid processing of monetary gains and losses". ...
... there is less brain volume in the frontal cortex and temporal lobes, and problems within the corpus callosum, the band of nerve ... delirium can cause visual hallucinations, or an unpredictable changing levels of consciousness. Schizophrenia occurs along with ...
The increased visual, physical, and cognitive stimulation all translates into more neuronal activity and synaptic communication ... cortex, and basal forebrain-areas vital to learning, memory, and higher thinking.[12] BDNF is also expressed in the retina, ... It has been shown that BDNF mRNA levels are decreased in cortical layers IV and V of the dorsolateral prefrontal cortex of ... "BDNF regulates reelin expression and Cajal-Retzius cell development in the cerebral cortex". Neuron. 21 (2): 305-15. doi: ...
Cerebral cortices. *Visual cortex. *Auditory cortex. *Vestibular cortex. *Olfactory cortex. *Gustatory cortex ... The uncus houses the olfactory cortex which includes the piriform cortex (posterior orbitofrontal cortex), amygdala, olfactory ... The orbitofrontal cortex (OFC) is heavily correlated with the cingulate gyrus and septal area to act out positive/negative ... Destruction to olfactory bulb, tract, and primary cortex (brodmann area 34) results in anosmia on the same side as the ...
A few of the more common birth defects this drug can cause are hearing and visual impairment, missing or malformed earlobes, ... A possible biological basis for the case reports of depression involves decreased metabolism in the orbitofrontal cortex (OFC) ... Other brain regions regulated by retinoic acid and potentially disrupted by isotretinoin include the frontal cortex and the ...
ঐক্ষিক বহিঃস্তর (গুরুমস্তিষ্ক) (Visual cortex). *কান (Ear) *বহিঃকর্ণ (Outer ear) *কানের লতি (Earlobe) ...
"Visual Images as (opposed to?) Reason: The Argument of Eclipse of Reason." Conference Proceedings - National Communication ... He also conceded that at this stage of development there would be no cognition of pain in the cerebral cortex.[18] ... Petchesky, Rosalind Pollack (1987). "Fetal Images: The Power of Visual Culture in the Politics of Reproduction". Feminist ... "its visual distortions and verbal fraud" and said it "belongs in the realm of cultural representation rather than... medical ...
Visual area V2, or secondary visual cortex, also called prestriate cortex,[20] is the second major area in the visual cortex, ... Visual nerves run straight from the eye to the primary visual cortex to the Visual Association cortex. ... Middle temporal visual area (V5)[edit]. The middle temporal visual area (MT or V5) is a region of extrastriate visual cortex. ... the visual cortex in the left hemisphere receives signals from the right visual field, and the visual cortex in the right ...
... whose structural and functional organization provides an ideal model for understanding cerebral cortex in... ... Few regions in the brain have received as much attention and scrutiny as the visual cortex, ... Primate Visual Cortex. In: Peters A., Rockland K.S. (eds) Primary Visual Cortex in Primates. Cerebral Cortex, vol 10. Springer ... Visual Cortex Cytochrome Oxidase Squirrel Monkey Lateral Geniculate Nucleus Primate Visual Cortex These keywords were added by ...
... còrtex visual (ca); Visueller Cortex (de-ch); visueller Cortex (de); Visual cortex (en-gb); cortex visuel (fr); 视觉皮层 (zh); ... Visual cortex (en-ca); קליפת הראייה (he); เปลือกสมองส่วนการเห็น (th); Kora wzrokowa (pl); Synssenteret (nb); visuele cortex (nl ... Media in category "Visual cortex". The following 135 files are in this category, out of 135 total. ... Ultra-fast-speech-comprehension-in-blind-subjects-engages-primary-visual-cortex-fusiform-gyrus-and-1471-2202-14-74
An electrode array implanted into the optic nerve of rabbits selectively activates discrete regions of the primary visual ... Spatially selective activation of the visual cortex via intraneural stimulation of the optic nerve *Vivien Gaillet ... the lateral geniculate nucleus of the thalamus and the primary visual cortex (V1) - have either been developed or are in ... visual prostheses that target nearly every stage of the early visual pathway1 - in particular, the retina, the optic nerve, ...
Unlike previous studies of repetition attenuation in visual cortex, which focused on similarity in terms of visual features, we ... Spatiotemporal object continuity in human ventral visual cortex. Do-Joon Yi, Nicholas B. Turk-Browne, Jonathan I. Flombaum, Min ... Spatiotemporal object continuity in human ventral visual cortex. Do-Joon Yi, Nicholas B. Turk-Browne, Jonathan I. Flombaum, Min ... these results suggest that spatiotemporal cues may affect computations of object identity in visual cortex for various visual ...
We studied ventral visual cortex, an area of the brain that responds selectively to visual categories (faces, places, and words ... Unlike frontal cortex, there is relatively little age-related atrophy in visual cortex with age as measured by volumetric ... Aging reduces neural specialization in ventral visual cortex. Denise C. Park, Thad A. Polk, Rob Park, Meredith Minear, Anna ... Aging reduces neural specialization in ventral visual cortex. Denise C. Park, Thad A. Polk, Rob Park, Meredith Minear, Anna ...
The extrastriate visual cortex of the monkey has in recent decades come to include an ever-expanding portion of the neocortical ... Visual Cortex Superior Colliculus Visual Area Primary Visual Cortex Macaque Monkey These keywords were added by machine and not ... Part of the Cerebral Cortex book series (CECO, volume 12). Abstract. The extrastriate visual cortex of the monkey has in recent ... Innocenti, G. M., 198Ib, Role of axon elimination in the development of visual cortex, in: Development of Visual Pathways in ...
An oblique effect in human primary visual cortex.. Furmanski CS1, Engel SA. ... Visual perception critically depends on orientation-specific signals that arise early in visual processing. Humans show greater ... to measure an asymmetry in the responses of human primary visual cortex (V1) to oriented stimuli. We found that neural ...
Advances in understanding visual cortex plasticity.. McCoy PA1, Huang HS, Philpot BD. ... Activation of plasticity gene expression contributes to the ocular dominance plasticity in the visual cortex. LGN: lateral ... Visual cortical plasticity can be either rapid, occurring in response to abrupt changes in neural activity, or slow, occurring ... Visual experience (light) can activate ERK and its downstream neural targets, MSK and CREB. CREB-mediated transcription is ...
Contribution of brain with or without visual cortex lesion to exploratory locomotion in the rat  ...
Mammalian species generally have multiple visual field maps with each species having similar, but not identical, maps. The ... Much of the visual cortex is organized into visual field maps: nearby neurons have receptive fields at nearby locations in the ... Much of the visual cortex is organized into visual field maps: nearby neurons have receptive fields at nearby locations in the ... Visual field maps in human cortex Neuron. 2007 Oct 25;56(2):366-83. doi: 10.1016/j.neuron.2007.10.012. ...
Visual Cortex lyrics by Schaft: Alive in the desert heat, the sun holds her heart / As it drains every breath and tears limbs ... Schaft - Visual Cortex lyrics. Alive in the desert heat, the sun holds her heart. As it drains every breath and tears limbs ... Lyrics taken from ...
Visual Cortex Neuron. This is a fluorescently tagged primary visual cortex neuron from a light microscope capture of a brain ... Part IX: Brain Visual Areas *The Primary Visual Cortex by Matthew Schmolesky ... Tag: visual cortex neuron. Posted on April 5, 2013. January 3, 2016. ... Regeneration in the Goldfish Visual System by Sam Nona. *Regeneration in the visual system of adult mammals by Yves Sauve and ...
The primary visual cortex (also known as striate cortex, area 17, and V1) lies at the back of the head, where it occupies ∼1200 ... Primary visual cortex (V1) is the largest of many visual areas and (in primates) the first to receive information directly from ... Functional Retinotopy of Monkey Visual Cortex. Gary Blasdel and Darlene Campbell. Journal of Neuroscience 15 October 2001, 21 ( ... 1974) Visual field of representation in layer IVC of monkey striate cortex. Soc Neurosci Abstr 10:264. ...
... We approach the visual coding in the cortex by considering the statistical ... In fact, the basis patches have the principal properties of the classical receptive fields of simple cells in the visual cortex ... and thus to model further properties of the visual cortex. Patrik Hoyer & Aapo Hyvarinen. March 2001. ... It is reasonable to assume that the visual system is adapted to process the particular kind of input it receives. ...
2003) Visual field representations and locations of visual areas V1/2/3 in human visual cortex. J Vis 3:586-598. ... 2007) Two-dimensional mapping of the central and parafoveal visual field to human visual cortex. J Neurophysiol 97:4284-4295. ... 2001) Where is dorsal V4 in human visual cortex? Retinotopic, topographic and functional evidence. Cereb Cortex 11:298-311. ... 2000) Visual areas in lateral and ventral extrastriate cortices of the marmoset monkey. J Comp Neurol 422:621-651. ...
Removal of afferent input to the somatosensory, auditory, motor or visual cortex results in a marked change of cortical ... Receptive field dynamics in adult primary visual cortex Nature. 1992 Mar 12;356(6365):150-2. doi: 10.1038/356150a0. ... At the level of the lateral geniculate nucleus, which provides the visual input to the striate cortex, a large silent region ... Removal of afferent input to the somatosensory, auditory, motor or visual cortex results in a marked change of cortical ...
Visual cortex. The term visual cortex refers to the primary visual cortex (also known as striate cortex or V1) and extrastriate ... visual cortical areas such as V2, V3, V4, and V5. The primary visual cortex is anatomically equivalent to Brodmann area 17, or ... Humans have the best of all possible visual worlds because our full stereo vision combines with primitive visual pathways to ... In humans and other mammals, the cerebral cortex is responsible for sensory, motor, and cognitive functions. Understanding the ...
... primary visual cortex has been shown to have reduced responses to visual stimulation [5]. It is not known, however, to what ... Primary visual cortex (V1) was clearly identifiable along the calcarine sulcus in all hemispheres. There was a significant ... extent aging affects visual field repre-sentations and population receptive sizes in human primary visual cortex. Here we use ... Understanding the extent of changes that occur in primary visual cortex during normal aging is essential both for understanding ...
In classical models of the visual system, information flows from primary visual cortex (V1) to more specialized, downstream ... The mouse primary visual cortex (V1) neurons were found to have a high degree of projectional diversity and most of the ... Each panel in the background shows the traced axon of a single neuron from the upper layers of primary visual cortex. The grey ... Read the full paper in Nature: The logic of single-cell projections from visual cortex By Yunyun Han, et al. ...
Functional studies have shown that columns relating to different response properties are mapped in cortex at different spatial ... In this review we re-examine the concept of a cortical column in macaque primary visual cortex, and consider to what extent a ... title = {Anatomical substrates for functional columns in macaque monkey primary visual cortex},. journal = {Cerebral Cortex},. ... In this review we re-examine the concept of a cortical column in macaque primary visual cortex, and consider to what extent a ...
Optical imaging has revealed that the visual cortex is the site of numerous functional maps associated with visual objects such ... Visual cortex and the Retinex algorithm Author(s): Jack D. Cowan; Paul C. Bressloff ... We show how such functional or feature maps may be used to analyze how visual objects may be represented by integrated neural ... as their position in the visual field, the local orientation of their contours, their texture and surface properties, and some ...
Figure 8. Visual input to the brain goes from eye to LGN and then to primary visual cortex, or area V1, which is located in the ... The macaque primary visual cortex, like that of all mammals studied, resides in the posterior pole of the occipital cortex (Fig ... Part IX: Brain Visual Areas *The Primary Visual Cortex by Matthew Schmolesky ... we should turn our attention to the current understanding of the primary visual cortex and its place in the visual pathways. ...
... appears to obtain visual data directly from an evolutionarily ancient sensory processing center at the base of the brain called ... In contrast to the dogma that all visual areas in the cerebral cortex get their inputs from primary visual cortex (V1), the new ... visual cortex, similar to a simple early amphibian, reptilian or avian visual cortex, and that it may be dedicated to the ... "We silenced the main visual area in the cortex and visual responses in POR remained unaffected. That was the first big wow ...
Visual Cortexes: Brain-Art Competition Shows Off Neurosciences Aesthetic Side. To highlight the artistic effort ... I]n my language the brain stem is called the brain tree trunk (hjernestamme) and the brain cortex is called the brain tree ... This image completely maximizes the amount of cortex tissue you can see, but doesnt distort it so you cant recognize the ... LA MIE DE BRAIN Translated as crumbs of the brain, this illustration of the cerebral cortex depicts the transition in early ...
ICD-9 code 377.7 for Disorders of visual cortex is a medical classification as listed by WHO under the range - DISORDERS OF THE ... Disorders of visual cortex (377.7). ICD-9 code 377.7 for Disorders of visual cortex is a medical classification as listed by ...
Interhemispheric synchronization of oscillatory neuronal responses in cat visual cortex. By AK Engel, P Konig, AK Kreiter, W ... Interhemispheric synchronization of oscillatory neuronal responses in cat visual cortex. By AK Engel, P Konig, AK Kreiter, W ... Interhemispheric synchronization of oscillatory neuronal responses in cat visual cortex Message Subject. (Your Name) has ...
... the retrosplenial cortex) located in the same sections used for the counts in the visual cortex. DR also caused a reduction in ... A) Neurocan and (B) WFA staining in the primary visual cortex (Oc1b) of P22, P70, and P100 animals. (C and D) Density of cells ... CSPG degradation restores OD plasticity in the adult visual cortex. (A to D) MD has no effect in adult rats. OD distributions ... Reactivation of Ocular Dominance Plasticity in the Adult Visual Cortex Message Subject. (Your Name) has forwarded a page to you ...
  • The visual cortex of the brain is a part of the cerebral cortex that processes visual information . (
  • The visual cortex receives its blood supply primarily from the calcarine branch of the posterior cerebral artery . (
  • Other studies, however, provide strong support for the idea that skilled actions such as grasping are not affected by pictorial illusions [7] [8] and suggest that the action/perception dissociation is a useful way to characterize the functional division of labor between the dorsal and ventral visual pathways in the cerebral cortex. (
  • Few regions in the brain have received as much attention and scrutiny as the visual cortex, whose structural and functional organization provides an ideal model for understanding cerebral cortex in general. (
  • In humans and other mammals, the cerebral cortex is responsible for sensory, motor, and cognitive functions. (
  • Felleman, D.J. and Essen, D.C.V. (1991) Distributed hierarchical processing in the primate cerebral cortex. (
  • Cerebral Cortex, 1, 1-47. (
  • 1996) Mapping striate and extrastriate visual areas in human cerebral cortex. (
  • The visual cortex of the brain is the area of the cerebral cortex that processes visual information. (
  • In contrast to the dogma that all visual areas in the cerebral cortex get their inputs from primary visual cortex (V1), the new study shows that postrhinal cortex (POR) gets information about moving objects via a parallel visual pathway from an evolutionarily ancient brainstem area called superior colliculus. (
  • Dr. David Fitzpatrick, Scientific Director and CEO at the Max Planck Florida Institute for Neuroscience (MPFI), has been awarded a $2 million four-year grant from the National Eye Institute (NEI) of the National Institutes of Health (NIH) to study the functional organization of neural circuits in the cerebral cortex, specifically, in the area of brain responsible for processing visual information. (
  • The cerebral cortex is the largest and most complex area of the brain, comprising 20 billion neurons and 60 trillion synapses-a neuronal network whose proper function is critical for sensory perception, motor control, and cognition. (
  • With the research supported by this grant, we aim to address a major gap in our understanding of how neurons in the cerebral cortex process information," said Dr. Fitzpatrick. (
  • We report here on (1) a summary of the layout of cortical areas associated with vision and with other modalities, (2) a computerized database for storing and representing large amounts of information on connectivity patterns, and (3) the application of these data to the analysis of hierarchical organization of the cerebral cortex. (
  • In this paper I will review some characteristics of cortical visuotopic maps in adults, and the implications that they may have for our understanding of the development and evolution of the cerebral cortex. (
  • 1 The cerebral cortex, however, is not a homogeneous, two-dimensional mantle. (
  • In this review, we highlight key findings from our group that shed light on neuronal activity patterns within the three-dimensional volume of the cerebral cortex. (
  • We examined the role of cerebral vasodilation caused by metabolic activation (ie, visual stimulus) on autoregulatory characteristics in the 2 vascular territories. (
  • We used TCD to simultaneously study dynamic cerebral autoregulation of the PCA and MCA territories in healthy volunteers using frequency domain analysis and tested the effect of visual activation on autoregulation of the posterior cerebral circulation. (
  • Neuronal response properties in the cerebral cortex are not static. (
  • We hypothesize that visual cortex neurodegeneration in experimental glaucoma (DBA/2J mice) is more pronounced than in other areas of cerebral cortex and is related to extensive glutamate toxicity. (
  • Pyramidal neurons (PNs) are the principal cells of the cerebral cortex, and despite their general similarity from area to area, must somehow participate in a diversity of sensory, motor, and memory-related computations. (
  • I. V. Bondar, E. E. Minakova, and R. S. Ivanov, "Using optical mapping of the internal signal to test the function of the visual cerebral cortex in mammals," J. Opt. (
  • Optical mapping of the internal signal is a unique method of studying the brain and makes it possible to investigate the functional anatomy of the cerebral cortex with high spatial resolution. (
  • Visual nerves run straight from the eye to the primary visual cortex to the Visual Association cortex. (
  • The part of the visual cortex that receives the sensory inputs from the thalamus is the primary visual cortex, also known as visual area 1 (V1), and the striate cortex. (
  • The primary visual cortex (V1) is located in and around the calcarine fissure in the occipital lobe . (
  • They originate from primary visual cortex. (
  • The part of the visual cortex that receives the sensory inputs from the thalamus is the primary visual cortex, also known as visual area 1 (V1, Brodmann area 17), and the striate cortex. (
  • An electrode array implanted into the optic nerve of rabbits selectively activates discrete regions of the primary visual cortex. (
  • Inspired by the successes of cochlear prostheses and deep-brain stimulators, visual prostheses that target nearly every stage of the early visual pathway 1 - in particular, the retina, the optic nerve, the lateral geniculate nucleus of the thalamus and the primary visual cortex (V1) - have either been developed or are in development. (
  • An oblique effect in human primary visual cortex. (
  • Here we used functional magnetic resonance imaging (fMRI) to measure an asymmetry in the responses of human primary visual cortex (V1) to oriented stimuli. (
  • This is a fluorescently tagged primary visual cortex neuron from a light microscope capture of a brain slice preparation. (
  • The operations of primary visual cortex generate continuous representations of orientation, ocular dominance, and retinotopy that, to fit in two dimensions, organize at separate but overlapping scales (e.g., 20-500 μm, 200 μm to 5 mm, and 2-33 mm). (
  • Primary visual cortex (V1) is the largest of many visual areas and (in primates) the first to receive information directly from the lateral geniculate nucleus (LGN). (
  • The term visual cortex refers to the primary visual cortex (also known as striate cortex or V1 ) and extrastriate visual cortical areas such as V2 , V3 , V4 , and V5 . (
  • The primary visual cortex is anatomically equivalent to Brodmann area 17 , or BA17. (
  • In normally aging subjects, primary visual cortex has been shown to have reduced responses to visual stimulation [5]. (
  • It is not known, however, to what extent aging affects visual field repre-sentations and population receptive sizes in human primary visual cortex. (
  • Here we use func-tional MRI (fMRI) and population receptive field (pRF) modeling [6] to measure angular and ec-centric retinotopic representations and population receptive fields in primary visual cortex in healthy aging subjects ages 57 - 70 and in healthy young volunteers ages 24 - 36 (n = 9). (
  • Primary visual cortex (V1) was clearly identifiable along the calcarine sulcus in all hemispheres. (
  • Understanding the extent of changes that occur in primary visual cortex during normal aging is essential both for understanding the normal aging process and for comparisons of healthy, aging subjects with aging patients suffering from age-related visual and cortical disorders. (
  • Brewer, A. and Barton, B. (2012) Effects of healthy aging on human primary visual cortex. (
  • 2008) The effect of age and fixation instability on retinotopic mapping of primary visual cortex. (
  • In classical models of the visual system, information flows from 'primary' visual cortex (V1) to more specialized, downstream areas that focus for example on image movement or image form. (
  • Each panel in the background shows the traced axon of a single neuron from the upper layers of primary visual cortex. (
  • Up until now, it had remained unclear as to whether information transfer from primary visual cortex was largely "one neuron - one target area", or if individual neurons distributed their signals across multiple downstream areas. (
  • the scientists found that these were the exception and that the majority of primary visual cortex neurons broadcast information to multiple targets. (
  • The mouse primary visual cortex (V1) neurons were found to have a high degree of projectional diversity and most of the individual layer 2/3 neurons were found to distribute information to multiple areas rather than projecting to a single target. (
  • In this review we re-examine the concept of a cortical column in macaque primary visual cortex, and consider to what extent a functionally defined column reflects any sort of anatomical entity that subdivides cortical territory. (
  • The primary visual cortex is the most studied visual area in the brain. (
  • clarification needed] The primary visual cortex, which is defined by its function or stage in the visual system, is approximately equivalent to the striate cortex, also known as Brodmann area 17, which is defined by its anatomical location. (
  • The primary visual cortex is divided into six functionally distinct layers, labeled 1 to 6. (
  • The average number of neurons in the adult human primary visual cortex in each hemisphere has been estimated at around 140 million. (
  • I will begin with a historical perspective on visual system research, and continue by attempting to answer the two basic questions posed above in relation to the primary visual cortex or V1. (
  • According to the standard model of visual processing, all visual information from the retina must first pass through the primary visual cortex (V1) in the back of the brain, which extracts simple features like lines and edges, before being distributed to a number of "higher order" visual areas that extract increasingly complex features like shapes, shading, movement, and so on. (
  • It's as if we've discovered a second primary visual cortex," said study senior author Massimo Scanziani , PhD, a professor of physiology at UCSF and a Howard Hughes Medical Institute investigator. (
  • this article we investigate to what extent the statistical properties of natural images can be used to understand the variation of receptive field properties of simple cells in the mammalian primary visual cortex. (
  • In this work we focus on studying primary visual area V1, by using firing rate ring model with short-term synaptic depression (STD). (
  • In this work we focus on studying how information processing in primary visual area V1 depends on cortical state. (
  • Orientation selectivity of primary visual cortical neurons is an important requisite for shape perception. (
  • Typically, monocular deprivation in early postnatal days leads to a shift in the dominant responses of primary visual cortical neurons to the non-deprived, experienced eye [1] - [4] . (
  • In this study, we used these technical improvements to determine the critical period for orientation plasticity in cat primary visual cortex. (
  • Researchers have shows the post rhinal cortex obtains visual data from the superior colliculus and is not dependent upon information from primary visual cortex. (
  • Experiments on kittens in the 1960s showed that the primary visual cortex contains neurons that fire selectively to straight lines of specific orientations. (
  • The effect of sensory experience on the orientation selectivity of neurons in the primary visual cortex is, however, unknown. (
  • Rearing the mice in this way had a significant effect on the properties of neurons in the primary visual cortex. (
  • These findings show that there is a critical period of plasticity between 4 and 7 weeks, during which cells in the primary visual cortex are particularly sensitive to sensory experience and that plasticity persists in older animals, albeit to a lesser extent. (
  • In the mammalian visual system, early stages of visual form processing begin with orientation-selective neurons in primary visual cortex (V1). (
  • Through massively parallel computational simulations, we studied how a large network of simple neural elements (the RF-LISSOM model) could develop a functional organization similar to that of the primary visual cortex. (
  • Here we show that contrast adaptation in mouse primary visual cortex depends on the behavioral relevance of the stimulus. (
  • Primary visual cortex is a key stage of visual processing with involvement in many circuits proposed for these applications including motion tracking, object recognition, and control of eye movements. (
  • As an initial application of this strategy we mapped the retinal projection topography of human primary visual cortex. (
  • The dopamine level of the nigrostriatal system decreased significantly and the uptake ratios of the primary visual cortex dropped obviously in the FOG group compared with the non-FOG group. (
  • Our study suggests that both the dopaminergic pathway and the primary visual cortex are involved in the pathogenesis of FOG. (
  • This anatomical specificity is such that information coming from topographically corresponding points of the two retinae converges onto single cells in the primary visual area (V1), and cells in adjacent regions of the same retina project to adjacent points of V1. (
  • We focus on studies of ongoing local field potential (LFP) data obtained simultaneously from multiple sites in the primary visual cortex in two types of experiments in which electrode contacts were spaced either along the cortical surface or at different laminar positions. (
  • A model is proposed to demonstrate how neurons in the primary visual cortex could self-organize to represent the direction of motion. (
  • Their studies focused on a micro-RNA molecule called miR-132, which was shown to steadily increase in abundance as the brain region responsible for vision, primary visual cortex, matured. (
  • This thesis explores contrast adaptation and its mechanisms in mouse primary visual cortex (V1). (
  • We used Western blot analysis of postmortem tissue from human primary visual cortex ( n = 30, range: 20 days to 80 years) to quantify expression of eight pre- and post-synaptic GABAergic markers. (
  • The activities of neurons in primary visual cortex have been shown to be significantly influenced by stimuli outside their classical receptive fields. (
  • Electrode recordings and imaging studies have revealed that localized visual stimuli elicit waves of activity that travel across primary visual cortex. (
  • Lipid pathway alterations in Parkinson's disease primary visual cortex. (
  • A visual discrimination task was used to examine changes in LTP in the primary visual cortex (V1) of adult rats. (
  • Brain activity corresponding to "reward timing has been observed in higher-order brain regions, but never in the primary visual cortex," Bear said. (
  • Here we show that estrogen-associated circuits are highly prevalent in the mouse primary visual cortex (V1). (
  • 3. We find that the variability of firing is much higher in cells of primary visual cortex in the anesthetized cat than in slice. (
  • We compared these predictions with spikes recorded from the cat's primary visual cortex under a standard protocol. (
  • The early steps in this processing chain, from retina to the primary visual cortex, are highly local, and the perception of more complex shapes requires integration of the local information. (
  • We examined visually evoked potentials (VEP) in the primary visual cortex ipsilateral and contralateral to the crushed nerve. (
  • In this dissertation, electrophysiological recordings of population activity in cat primary visual cortex were made while either the SC or pMS were deactivated. (
  • The goal of this experimental set- up was to ascertain the effects of SC or pMS deactivation on the electrophysiological population signal as a visual stimulus enters the cortical processing network at its main entry point, primary visual cortex. (
  • The results are as follows: in the awake cat performing a visual perimetry task (project 4), neural activity when 1) unilateral pMS was deactivated and contralateral stimuli neglected versus when 2) pMS was active and stimuli were attended, reveals a significant drop in high-frequency gamma (52-90 Hz) oscillations and low-frequency theta (4-8 Hz) oscillations bilaterally in primary visual cortex. (
  • A cooling induced interhemispheric imbalance in gamma power, as found in passive-viewing projects 1-3, could explain visual hemineglect because the primary visual cortex respresenting the neglected hemifield has less gamma power than the hemisphere responsible for the intact visual hemispace. (
  • In the current study, we examine the distribution of PNNs and the identity of PNN-enwrapped neurons in three brain areas with different cognitive functions: the dorsal hippocampus, medial entorhinal cortex (mEC) and primary visual cortex (V1). (
  • The primary visual cortex in these patients slowly became activated by the artificial visual stimulation, indicating that sight restoration therapies can rely on a considerable degree of spared plasticity in adulthood. (
  • Primary visual cortex (V1) is the first stage of cortical image processing, and a major effort in systems neuroscience is devoted to understanding how it encodes information about visual stimuli. (
  • To study mechanisms for an integration of stimulus information distributing wide area in the visual field, we examined modulatory effects of visual responses of neurons by grating stimuli presented outside of receptive field in the primary visual cortex of anesthetized cats. (
  • We previously demonstrated that a coarse-scale bias for radial orientations in human primary visual cortex (V1) is both necessary and sufficient for orientation decoding. (
  • Here, I tested the hypothesis that field postsynaptic potentials (fPSPs) in the rat primary visual cortex (V1) evoked by single pulse stimulation of the lateral geniculate nucleus (LGN) can be potentiated when LGN stimulation is paired with short bursts of stimuli applied to the basal forebrain (BF), the major source of ACh released in the cortex. (
  • The modeled cells capture a wide range of receptive field properties of orientation selective cortical cells in the primary visual cortex. (
  • Wörgötter, F., Koch, C.: A detailed model of the primary visual pathway in the cat: Comparison of afferent excitatory and intracortical inhibitory connection schemes for orientation selectivity. (
  • The extrastriate cortex is the region of the occipital cortex of the mammalian brain located next to the primary visual cortex. (
  • Primary visual cortex (V1) is also named striate cortex because of its striped appearance in the microscope. (
  • Neurons in the visual cortex fire action potentials when visual stimuli appear within their receptive field . (
  • Using high-resolution fMRI (1.2 × 1.2 × 1.2 mm 3 ) and carefully designed visual stimuli, we sought to accurately map the human foveal confluence and hence disambiguate the competing theories. (
  • The human visual system can detect and discriminate between an incredibly diverse assortment of stimuli that may be chromatic or achromatic, in motion or not, pattered or unpatterned, two-dimensional or three. (
  • Remarkably, the neural end-product of visual stimuli impacting upon the retina is, in one sense, always the same. (
  • The research was launched when lead author Riccardo Beltramo , PhD, a postdoctoral researcher in the Scanziani lab, was recording neural responses to moving visual stimuli in the mouse POR, which is known to play roles in perceiving motion and in spatial memory. (
  • We varied the attentional load of a visual monitoring task performed on a rapid stream at central fixation without altering the central stimuli themselves, while measuring the impact on fMRI responses to task-irrelevant peripheral checkerboards presented either unilaterally or bilaterally. (
  • The new method computes a model of the population receptive field from responses to a wide range of stimuli and estimates the visual field map as well as other neuronal population properties, such as receptive field size and laterality. (
  • Load Theory of attention suggests that high perceptual load in a task leads to reduced sensory visual cortex response to task-unrelated stimuli resulting in "load-induced blindness" [e.g. (
  • If VSTM load draws on sensory visual capacity, then similar to perceptual load, high VSTM load should also reduce visual cortex response to incoming stimuli leading to a failure to detect them. (
  • The main motivation for choosing V1 for this study is the fact that it is widely believed to be responsible for processing simple features of visual stimuli, in particular the orientation of stimulus edges. (
  • Specially designed goggles modify visual input so that only vertically oriented stimuli are perceived. (
  • To investigate, Tanaka and his colleagues reared mice and fitted them with specially designed goggles through which they can only perceive vertically oriented visual stimuli , for a one-week period, between 3 and 15 weeks of age. (
  • To test the behavioral dependence of cortical response adaptation, we presented sustained moving grating stimuli to mice in different behavioral states and in conditions with different behavioral relevance of the visual test stimulus. (
  • They measure the increase by holding the mouse's head still and then presenting the mouse with visual stimuli in the form of black and white horizontal stripes that rotate around the mouse. (
  • Here, we demonstrate that neurons in the ventrolateral prefrontal cortex (vlPFC) of monkeys performing a shape discrimination task respond more strongly to occluded than unoccluded stimuli. (
  • In contrast, neurons in visual area V4 respond more strongly to unoccluded stimuli. (
  • Following training, trained, control, and task-naïve rats were anesthetized and visual evoked potentials (VEPs) in V1 were recorded in response to CS+, CS-, and novel stimuli. (
  • But neurons in the intact animal fire irregularly in response to constant current injection as well as to visual stimuli. (
  • The response to current injected from an intracellular electrode in vivo is also variable, but slightly more regular and less bursty than in response to visual stimuli. (
  • Visual hemineglect is a pathology where damage to any of a number of areas in the brain can result in visual stimuli contralateral to neural damage not entering perceptual awareness. (
  • Along this line, loss of gamma power would indicate a break-down in network communication that leads to a neglect of contralateral visual stimuli. (
  • This suggests that early visual cortex is the site of capacity limits, where finite processing resources must be divided among attended stimuli. (
  • In both experiments, blood-oxygen level-dependent (BOLD) signals in the retinotopic cortex were significantly lower for ignored than attended stimuli. (
  • The present study bridges that gap by measuring the effects of divided spatial attention on both behavioral and neuronal responses to simple visual stimuli. (
  • Of special significance is the discovery by Hubel and Wiesel (1968) of ocular dominance columns, orientation columns, and the exquisite system of functional modules in the primate striate cortex. (
  • Functional neuroimaging studies of healthy young adults have revealed that different parts of ventral visual cortex respond maximally to faces ( 18 ), to places ( 19 - 20 ), and to orthography ( 21 ). (
  • Visual field maps have been linked to functional and perceptual properties of the visual system at various spatial scales, ranging from the level of individual maps to map clusters to dorsal-ventral streams. (
  • 1995) Borders of multiple visual areas in humans revealed by functional magnetic resonance imaging. (
  • Functional studies have shown that columns relating to different response properties are mapped in cortex at different spatial scales. (
  • Optical imaging has revealed that the visual cortex is the site of numerous functional maps associated with visual objects such as their position in the visual field, the local orientation of their contours, their texture and surface properties, and some aspects of their color. (
  • We show how such functional or feature maps may be used to analyze how visual objects may be represented by integrated neural population activity, and how such activity may embody algorithms similar to the Retinex algorithm. (
  • The purpose of the present study was to demonstrate the utility of NIRS in functional imaging of the human visual cortex. (
  • We show that reconstruction of visual features from V1 activity depends on the functional state, with best precision achieved at the state with intermediate release probability. (
  • Numerous experimental observations show that during different functional states cortex generates different activity dynamics, characterized in particular by different degree of syncrhonization. (
  • Functional imaging of the visual cortex during wakefulness a. (
  • Previous studies in primates and humans found a strong and reproducible visually induced functional magnetic resonance imaging (fMRI) signal in the visual cortex during mild isoflurane anaesthesia. (
  • Neuronal circuits in the mammalian visual cortex maintain certain dynamic mechanisms of structural and functional modification in the early postnatal period as well as in adulthood. (
  • However, despite the rich literature on visual contour processing, there is little understanding on how functional architecture within single orientation columns may contribute to the generation of different elemental aspects of visual contours (such as linear oriented segments, curved segments, corners, and T junctions) ( 4 - 7 ). (
  • We demonstrate the feasibility of using recently developed high-density diffuse optical tomography (HD-DOT) to map functional activation of the visual cortex in healthy term-born infants. (
  • Citation Query Antibody labeling of functional subdivisions in visual cortex: cat-301 immunoreactivity in striate and extrastriate cortex of the macaque. (
  • The pioneering work of Hubel and Wiesel defined the fundamental challenge in understanding the functional organization of visual cortex: How do cortical circuits transform the information supplied by different populations of retinal ganglion cells into coherent representations of the visual world? (
  • Third, a possible functional role for the lateral connections in the cortex was verified in the model. (
  • The study, published in the journal Current Biology , involved conducting five different experiments using functional Magnetic Resonance Imaging (fMRI) to examine the activity in the early visual cortex in 10 volunteer subjects. (
  • Previous studies demonstrated that alterations in functional MRI derived receptive field (pRF) properties in cortical projection zones of retinal lesions can erroneously be mistaken for cortical large-scale reorganization in response to visual system pathologies. (
  • Functional maturation of visual cortex is linked with dynamic changes in synaptic expression of GABAergic mechanisms. (
  • Very little is known about the effects of aging on the structural and functional properties of early visual field maps in human visual cortex. (
  • We study such functional and structural plasticity in the visual cortex, using imaging approaches that allow following the fate of individual neurons over extended periods of time. (
  • We bridged that gap by using functional magnetic resonance imaging to measure responses in the human visual cortex during simple feature detection. (
  • It is shown to be possible in principle to use optical mapping of the internal signal to objectively test the visual function: As the contrast of the visual stimulus changes, changes have been observed in both the amplitude of the metabolic response in the cortex and in the structure of the functional maps. (
  • The extrastriate cortex encompasses multiple functional areas, including V3, V4, V5/MT, which is sensitive to motion, or the extrastriate body area (EBA) used in the perception of human bodies. (
  • Next, we will discuss the plasticity of extrastriate visual cortex in adulthood by examining the ability of extrastriate areas to function in parallel with striate cortex and the consequences of damage to extrastriate cortex in adult monkeys. (
  • In addition, we will examine evidence for learning-or experience-dependent plasticity in the response properties of neurons in extrastriate cortex. (
  • In the subsequent section, we will address the special plasticity associated with damage to visual cortex in developing animals. (
  • We will then briefly compare the development and plasticity of extratriate cortex in monkeys with phenomena described for other mammalian groups. (
  • Advances in understanding visual cortex plasticity. (
  • Visual cortical plasticity can be either rapid, occurring in response to abrupt changes in neural activity, or slow, occurring over days as a homeostatic process for adapting neuronal responsiveness. (
  • These observations suggest that activation of specific signaling pathways through discrete neuromodulator receptor subtypes dictates the direction of plasticity induced in visual cortex. (
  • Activation of plasticity gene expression contributes to the ocular dominance plasticity in the visual cortex. (
  • We tested whether the developmental maturation of the ECM is inhibitory for experience-dependent plasticity in the visual cortex. (
  • However, other factors present in the adult visual cortex could stabilize synaptic connections and limit experience-dependent plasticity. (
  • If CSPGs in PNNs are involved in limiting OD plasticity in adults, the formation of adult-like PNNs around visual cortical neurons should coincide with the end of the critical period. (
  • Although numerous studies have been previously devoted to a question of how orientation selectivity is established and elaborated in early life, how the susceptibility of orientation plasticity to visual experience changes in time remains unclear. (
  • Tanaka S, Tani T, Ribot J, O'Hashi K, Imamura K (2009) A Postnatal Critical Period for Orientation Plasticity in the Cat Visual Cortex. (
  • By peering into the eyes of mice and tracking their ocular movements, researchers made an unexpected discovery: the visual cortex - a region of the brain known to process sensory information - plays a key role in promoting the plasticity of innate, spontaneous eye movements. (
  • To test the visual cortex's role in the plasticity of these reflexes, the researchers applied a technique called optogenetics, which uses light to turn target cells on or off. (
  • Silencing the visual cortex led to a significant reduction in the activity of the optokinetic reflex, suggesting that it is the visual cortex that is involved in mediating the plasticity between the optokinetic and the vestibulo-ocular reflexes. (
  • When the brain matures normally, these micro-RNAs allow visual brain regions to preferentially strengthen certain connections in response to the light they experience from their surroundings, a process known as synaptic plasticity. (
  • This approach has been extended in a series of recent studies using pharmacological manipulations of GABA signaling, such as fluoxetine, to reinstate ocular dominance plasticity in adult visual cortex and facilitate recovery from amblyopia (Maya Vetencourt et al. (
  • Properties and plasticity of inhibitory synapses on fast-spiking (FS) GABAergic (FS-GABA) interneurons in layer II/III of the mouse visual cortex were examined in cortical slices by whole-cell recordings of IPSCs or IPSPs evoked by activation of presynaptic FS or non-FS GABAergic interneurons. (
  • For further analysis of inhibitory synaptic plasticity, IPSPs evoked by electrical stimulation of an adjacent site in the cortex were recorded from FS-GABA neurons. (
  • However, no studies have examined LTP-like plasticity in the visual cortex as a result of visual discrimination learning. (
  • Further, visual experience alters the plasticity properties of V1 (metaplasticity) by facilitating LTP along thalamocortical sensory fibers. (
  • In adult mice with unilateral optic nerve crush injury (ONC), we studied visual response plasticity in the visual cortex following stimulation with sinusoidal grating. (
  • Comparison of the effects of dark rearing and binocular suture on development and plasticity of cat visual cortex. (
  • In this review we summarize studies showing that the visual brain of sighted adults retains a type of developmental plasticity, called homeostatic plasticity, and this property has been recently exploited successfully for adult amblyopia recover. (
  • During the induction of plasticity, participants engaged in a visual detection task with either low or high attentional demands. (
  • These findings extend Load Theory to demonstrate a new form of competitive interactions between early visual cortex processing and visual representations held in memory under load and provide a novel line of support for the sensory recruitment hypothesis of VSTM. (
  • Using a special algorithm that can identify unique patterns in brain activity, the researchers were able to discriminate between the different sounds being processed in early visual cortex activity. (
  • A second experiment revealed even imagined images, in the absence of both sight and sound, evoked activity in the early visual cortex. (
  • The early visual cortex hasn't previously been known to process auditory information, and while there is some anatomical evidence of interconnectedness in monkeys, our study is the first to clearly show a relationship in humans. (
  • While the organization and function of early visual cortex (i.e. (
  • These results suggest that processing of simple features in early visual cortex has unlimited capacity. (
  • Using transcranial magnetic stimulation-induced phosphenes to probe cortical excitability, we observed decreased V5/MT excitability versus increased early visual cortex (EVC) excitability, during vestibular activation. (
  • Little is known, however, about how neural representations of objects, typically defined by visual features, are influenced by spatiotemporal continuity. (
  • These results indicate that spatiotemporal continuity modulates neural representations of object identity, influencing judgments of object persistence even in the most staunchly "featural" areas of ventral visual cortex. (
  • Moreover, visual similarity produces "repetition attenuation" in neural responses: a weaker neural response is typically observed to a repeated stimulus compared with a novel stimulus ( 11 - 14 ). (
  • Thus, in the present study, we test whether neural structures become dedifferentiated with age, by examining the degree of category-specificity that is present in ventral visual cortex in young and old adults. (
  • It has also recently been demonstrated that a variety of other object categories elicit distinct neural signatures in ventral visual cortex ( 22 ). (
  • Visual experience (light) can activate ERK and its downstream neural targets, MSK and CREB. (
  • Aging often results in reduced visual acuity from changes in both the eye and neural circuits [1-4]. (
  • An international collaboration of neuroscientists have today published a paper in Nature demonstrating the breadth of neural communication in visual cortex using a combination of methods for tracing the projections of individual neurons across the brain. (
  • A neural circuit for spatial summation in visual cortex. (
  • In this project, we develop and simulate a spiking neural network model of multiple interacting areas of macaque visual cortex, connected in a layer-specific fashion. (
  • A deeper understanding of how neural circuits develop and work together to process and transmit information is crucial for addressing numerous visual, neurological, and psychiatric disorders resulting from the dysfunction of these circuits in the brain. (
  • In visual cortex, neural responses to a sustained stimulus adapt over the course of a few seconds. (
  • Mammalian visual perception is enabled not only by neural processing but also by precise eye movements, which allow for efficient scanning of the environment. (
  • We propose that these contextual influences serve pre-attentive visual segmentation by causing relatively higher neural responses to important or conspicuous image locations, making them more salient for perceptual pop-out. (
  • For years, neural activity in the brain's visual cortex was thought to have only one job: to create visual perceptions. (
  • The neural basis of visual perception can be understood only when the sequence of cortical activity underlying successful recognition is known. (
  • Advanced recording techniques to monitor neural activity in the awake-behaving cat (project 4) while cortex was both active and deactivated were developed for this thesis to compliment thesis projects 1-3 involving classical recording techniques in animals passively viewing a square-wave visual stimulus. (
  • Our results suggest that neural connection among SF domains sharing similar SF preference is one of the basis of the contextual modulation of responses in the visual cortex. (
  • Importantly, object-selective cortical regions such as the lateral occipital cortex show such attenuation even though the repeated objects may differ in their sizes, orientations, or perceived depths, revealing cue-independent object representations ( 15 , 16 ). (
  • During the early postnatal development of the neocortex in rats there is an axonal projection from the occipital cortex (which includes the visual cortex) to the spinal cord which is subsequently completely removed through a process of selective collateral elimination. (
  • no labeled cells are seen in the occipital cortex. (
  • However, a similar FB injection made during the first postnatal week results after a 4-day survival in a continuous band of FB-labeled layer V neurons spread throughout the tangential extent of the neocortex, including the occipital cortex. (
  • Injections of the anterograde tracer wheat germ agglutinin conjugated to horseradish peroxidase made into the occipital cortex, or for comparison, into more rostral cortical regions in hamsters ranging in age from neonates to adults, reveal that the extension of pyramidal tract axons is staggered along the anterioposterior axis of the cortex such that axons originating from the posterior regions lag behind those arising from more rostral areas. (
  • Injections into the occipital cortex on P16 label only a few fibers in the medullary pyramidal tract, and none is labeled in hamsters injected as adults. (
  • In this regard, the optic nerve is attractive because its relatively small diameter facilitates the electrical stimulation of a much wider visual field, and the implantation of a device on or within the optic nerve should be simpler than for locations further downstream. (
  • In the visual cortex, for example, stimulation of a pyramidal cell's receptive-field surround can attenuate the cell's response to a stimulus in the centre of its receptive field, a phenomenon called surround suppression. (
  • Here we show that, in contrast to pyramidal cells, the response of somatostatin-expressing inhibitory neurons (SOMs) in the superficial layers of the mouse visual cortex increases with stimulation of the receptive-field surround. (
  • Attentional load and sensory competition in human vision: modulation of fMRI responses by load at fixation during task-irrelevant stimulation in the peripheral visual field. (
  • Activations in visual cortex for irrelevant peripheral stimulation decreased with increasing attentional load at fixation. (
  • A visual cortical prosthesis (VCP) has long been proposed as a strategy for restoring useful vision to the blind, under the assumption that visual percepts of small spots of light produced with electrical stimulation of visual cortex (phosphenes) will combine into coherent percepts of visual forms, like pixels on a video screen. (
  • In both sighted and blind participants, dynamic stimulation enabled accurate recognition of letter shapes predicted by the brain's spatial map of the visual world. (
  • In four of five subjects the visual cortex was the most activated area during visual stimulation. (
  • Accordingly, we hypothesized that visual stimulation might also activate the human visual cortex during intravenous anaesthesia. (
  • For visual stimulation a binocular flash stimulus (1.7 Hz) was presented as a block design composed of 8 stimulation periods alternating with resting periods defined by the absence of the experimental stimulus with both periods lasting 25s. (
  • Binocular visual stimulation during wakefulness as well as during propofol/remifentanil anaesthesia produced a significant activation in the visual cortex including the striate (Brodmann's area (BA) 17) and the extrastriate visual cortex (BA 18, 19). (
  • We quantified, for the cortical representation of the actually stimulated visual field, the changes in the position and size of the pRFs associated with reduced peripheral stimulation using conventional and advanced pRF modeling. (
  • Complex visual hallucinations are a well-known feature of electrical stimulation or epileptic discharge in the temporal lobe. (
  • Even though recent studies have demonstrated visual and memory functions in the prefrontal cortex, up to now epileptic discharge or electrical stimulation of prefrontal structures has only rarely been reported to induce visual phenomena. (
  • We report on two patients undergoing invasive presurgical epilepsy evaluation in which electrical cortical stimulation of the left prefrontal cortex repeatedly induced complex visual hallucinations. (
  • Traveling waves are present also during spontaneous activity, but they can be greatly reduced by widespread and intensive visual stimulation. (
  • We found that unilateral ONC induces enhancement of visual response on the side ipsilateral to the injury that is evoked by visual stimulation to the intact eye. (
  • In this experimental set-up the cat was anesthetized and square-wave gratings were used as a visual stimulation. (
  • Conclusion: Improvement of neglect after caloric stimulation in the acute phase was associated with increased fc of vestibular cortex areas in both hemispheres to the para-hippocampus and the dorsal anterior cingulum, but simultaneously with reduced interhemispheric VC connectivity. (
  • Next, we discuss how the brain circuits reorganizes when visual stimulation is partially restored by means of a bionic eye in late blinds with Retinitis Pigmentosa. (
  • Temporal characteristics of response integration evoked by multiple whisker stimulation in the barrel cortex of rats. (
  • We induced LTP-like effects in the hand area of the human motor cortex using transcranial magnetic stimulation (TMS). (
  • Visual information coming from the eye goes through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. (
  • Each hemisphere's V1 receives information directly from its ipsilateral lateral geniculate nucleus that receives signals from the contralateral visual hemifield. (
  • Visual information coming from the eyes passes through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. (
  • At the level of the lateral geniculate nucleus, which provides the visual input to the striate cortex, a large silent region remains. (
  • Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. (
  • Layer 4, which receives most visual input from the lateral geniculate nucleus (LGN), is further divided into 4 layers, labelled 4A, 4B, 4Cα, and 4Cβ. (
  • Though Galen accurately described much of the visual system gross anatomy, he did not recognize the decussation of fibers at the optic chiasm, nor did he trace the fibers to the dorsal lateral geniculate nucleus (LGNd) of the thalamus (Fig. 1). (
  • After intracardial perfusion, sections of the lateral geniculate nucleus (LGN) and visual cortex (V1) were examined by immunohistochemistry for glial fibrillary acidic protein (GFAP) and CD11b, a subunit of the complement 3 receptor and marker of macrophage and microglia cells (MAC-1). (
  • This loss has been shown to cause neurochemical changes in the lateral geniculate nucleus (LGN) and visual cortex of adult primates. (
  • Monocular deprivation effects in the rat visual cortex and lateral geniculate nucleus are prevented by nerve growth factor (NGF). (
  • Synaptic physiology of horizontal connections in the cat's visual cortex. (
  • We simulated the shape and amplitude of extracellular action potentials (APs or "spikes") using biophysical models based on detailed reconstructions of single neurons from the cat's visual cortex. (
  • The striation of a stimulus passing across a complex or supercomplex receptive field of a cat's visual cortex (RFVC) defines the characteristics of the field's responses. (
  • Unexpectedly, for the centermost 0.75°, the cortical representations for both V2 and V3 are larger than that of V1, indicating that more neuronal processing power is dedicated to second-level analysis in this small but important part of the visual field. (
  • The pRF method is non-invasive and can be applied to a wide range of conditions when it is useful to link fMRI signals in the visual pathways to neuronal receptive fields. (
  • In the visual system, prolonged exposure to a high contrast stimulus leads to a decrease in neuronal responsiveness, referred to as contrast adaptation. (
  • These experiments demonstrate that visual discrimination learning might involve stimulus-selective facilitation of neuronal responses at early stages of visual processing (LGN, V1). (
  • Correspondingly, neuronal response magnitudes in visual cortex are often reduced during divided compared with focused spatial attention. (
  • Mammalian species generally have multiple visual field maps with each species having similar, but not identical, maps. (
  • This undermines the whole concept of the visual system in mammalian cortex as a perfect hierarchy with V1 as the gatekeeper and raises a multitude of questions, including how these two parallel visual systems evolved and how they cooperate to produce a unified visual experience. (
  • The diversity of single-cell projections from mouse visual cortex revealed by fluorescence-based tracing. (
  • I sought to examine the expression of CP-AMPARs at synapses onto the two major classes of inhibitory interneuron in layer 5 of the mouse visual cortex, Basket cells (BCs) and Martinotti cells (MCs). (
  • Cell type-specific, presynaptic LTP of inhibitory synapses on fast-spiking GABAergic neurons in the mouse visual cortex. (
  • Abstract - I will describe recent studies in the lab on binocular interactions in striate and extra-striate visual cortex in normal and amblyopic vision. (
  • Much of the visual cortex is organized into visual field maps: nearby neurons have receptive fields at nearby locations in the image. (
  • In fact, the basis patches have the principal properties of the classical receptive fields of simple cells in the visual cortex. (
  • Here we remove visual input by focal binocular retinal lesions and record from the same cortical sites before and within minutes after making the lesion and find immediate striking increases in receptive field size for cortical cells with receptive fields near the edge of the retinal scotoma. (
  • As a result, cells in adjacent V1 columns always have receptive fields that represent slightly different, but overlapping portions of the visual field (1). (
  • 1994 ) and during aging the loss of orientation tuning in visual cortical receptive fields (Leventhal et al. (
  • For one thing, the functions performed by different areas of prefrontal cortex are poorly understood. (
  • A second problem is that prefrontal cortex exhibits disproportionate atrophy with age compared with other cortical areas ( 14 ). (
  • Verbal working memory load affects prefrontal cortices activation evidence. (
  • Overall, these data show that external landmarks influence prefrontal visual responses, likely helping to stabilize gaze goals in the presence of variable eye and head orientations. (
  • Based on the spatial organization of the visual experiences in our patients, animal work, and neuroimaging data it might be suggested that specific subregions of the human prefrontal cortex might contain separate visual and mnemonic processing mechanisms. (
  • To provide new insights, we investigated the role of the prefrontal cortex in the representation of occluded objects, focusing on how responses in this area compare to responses in the visual cortex, and how frontal and visual cortical areas might interact to facilitate recognition performance. (
  • The prefrontal cortex (PFC) plays an important role in cognitive control-the orchestration of thought and action in accordance with internal goals ( Miller and Cohen, 2001 ). (
  • Furthermore, markers of central sensory function (e.g., corrected visual and auditory acuity) account for virtually all age-related variance on a broad array of higher-order cognitive tasks, including speed of processing, memory, verbal fluency, and reasoning ( 4 , 6 ). (
  • In this chapter, discussion will be restricted (or broadened, depending upon one's viewpoint) to consideration of cortical zones shown to have at least some visual sensory responsiveness and direct connectivity with other, unimodal visual areas. (
  • Instead, this region, known as the post-rhinal cortex (POR), appears to obtain visual data directly from an evolutionarily ancient sensory processing center at the base of the brain called the superior colliculus. (
  • The ancestral superior colliculus (called optic tectum in non-mammals) is the main sensory processing center in creatures with little or no cortex, such as fish, amphibians, lizards and birds. (
  • Consideration of the findings that visual STM (VSTM) involves sensory recruitment [e.g. (
  • The numerous interactions between excitatory and inhibitory cells at each stage of visual processing result in cortical maps which depart in several ways from being precise point-to-point replicates of the sensory receptor surface. (
  • We focus on primate visual cortex as a model sensory system with well described anatomy that has been the subject of a large body of neurophysiological studies. (
  • Cortical sensory processing is widely studied in the visual cortex. (
  • When an object is partially occluded, relevant sensory evidence available to the visual system is diminished, making the process of object recognition challenging. (
  • Interaction of sensory responses with spontaneous depolarization in layer 2/3 barrel cortex. (
  • No one would have expected to see it there because the visual cortex is thought to be a detector of the physical features of the environment, with responses limited to those features to ensure that sensory processing is reliable and reproducible. (
  • Humans have the best of all possible visual worlds because our full stereo vision combines with primitive visual pathways to quickly spot danger, a study led by the University of Sydney has discovered. (
  • Figure 1 shows the arab adaptation of Galen¹s ideas on the pathways of the visual sytem from eyes to forebrain. (
  • The two parallel visual pathways are routed through distinct relay stations in a brain structure called the thalamus: dLGN for V1 and the Pulvinar for POR. (
  • Behavioral, anatomical, and neuroimaging measurements have demonstrated several changes in healthy aging visual pathways that may contribute to reduced visual acuity in aging. (
  • Using gas chromatography mass spectrometry techniques, 6 out of 7 oxysterols analysed from both non-enzymatic and enzymatic pathways were also selectively increased in the Parkinson's disease visual cortex. (
  • The aim of this study was to assess the effect of propofol/remifentanil anaesthesia on visual-evoked activation of the visual cortex using fMRI-technique. (
  • Additional visual detection experiments established a clear tradeoff between the amount of information maintained in VSTM and detection sensitivity, while ruling out alternative accounts for the effects of VSTM load in terms of differential spatial allocation strategies or task difficulty. (
  • Visual landmarks influence spatial cognition, navigation and goal-directed behavior, but their influence on visual coding in sensorimotor systems is poorly understood. (
  • These findings indicate the dependence of foveal pRF parameters on the spatial extent of the stimulated visual field and are likely associated with methodological biases and/or physiological mechanisms. (
  • Addressing this type of question requires simultaneous measurements at known spatial intervals in the cortex. (
  • Interestingly, the induced visual responses differed with respect to their spatial organization: whereas those evoked on the inferior frontal gyrus were perceived in the whole visual field, complex visual responses on the middle frontal gyrus were restricted to the contralateral hemispace. (
  • Performance in many visual tasks is impaired when observers attempt to divide spatial attention across multiple visual field locations. (
  • Swindale, N.V.: Spatial pattern of response magnitude and selectivity for orientation and direction in cat visual cortex. (
  • After a few months even the cortical areas that were initially silenced by the lesion recover visual activity, representing retinotopic loci surrounding the lesion. (
  • Increased VSTM load (manipulated by increased set size) led to reduced retinotopic visual cortex (V1-V3) responses to contrast as well as reduced detection sensitivity, as we predicted. (
  • The map is trained with moving Gaussian inputs, and it develops a retinotopic map with orientation columns that divide into areas of opposite direction selectivity, as found in the visual cortex. (
  • hence, retinotopic visual field maps are cortical regions in which nearby neurons analyze the properties of nearby points of an image on the retina. (
  • Retinotopic and nonretinotopic field potentials in cat visual cortex. (
  • The dorsal stream begins with V1, goes through Visual area V2, then to the dorsomedial area (DM/ V6) and Visual area MT (middle temporal/ V5) and to the posterior parietal cortex . (
  • Seeds in the vestibular [parietal operculum (OP2)], the parietal [posterior parietal cortex (PPC);7A, hIP3], and the visual cortex (VC) were used for the analysis. (
  • Decreases were more pronounced in the posterior cingulate/precuneous (BAS 31/7) and right inferior parietal cortex (BA 40) during language-related tasks and more pronounced in left inferior frontal cortex (BA 10/47) during nonlanguage tasks. (
  • Blood flow decreases did not generally show significant differences across the active task states within an experiment, but a verb-generation task produced larger decreases than a read task in right and left inferior parietal lobe (BA 40) and the posterior cingulate/precuneous (BA 31/7), while the read task produced larger decreases in left lateral inferior frontal cortex (BA 10/47). (
  • We hypothesized that visual responses in frontal cortex gaze control areas encode potential targets in an intermediate gaze-centered / landmark-centered reference frame that might depend on specific target-landmark configurations rather than a global mechanism. (
  • In order to obtain in vivo proton MR spectra two distinct voxels of interests (VOIs) corresponding to visual cortex (5x2x1.2 mm 3 ) and frontal cortex (4x2x1.5mm 3 ) were precisely positioned basing on T2-weighted images. (
  • 0.001) but not in the frontal cortex (1.084±0.021 vs. 1.169±0.033, ns. (
  • 0.05) in the visual cortex of DBA/2J mice than in the control mice, while no significant difference was observed in the frontal cortex (1.257±0.028 vs. 1.297±0.044, ns. (
  • Brewer, A.A. and Barton, B. (2012) Visual field map organization in human visual cortex. (
  • Von der Malsburg, C.: Self Organization of orientation selective cells in the striate cortex. (
  • The results indicate that the topographic reorganization within the cortex was largely due to synaptic changes intrinsic to the cortex, perhaps through the plexus of long-range horizontal connections. (
  • Comparing the balances between the pre- and post-synaptic markers we found three main transition stages (early childhood, early teen years, aging) when there were rapid switches in the composition of the GABAergic signaling system, indicating that functioning of the GABAergic system must change as the visual cortex develops and ages. (
  • Horizontal propagation of visual activity in the synaptic integration field of area 17 neurons. (
  • Koch, C., Poggio, T.: The synaptic veto mechanism: does it underlie direction and orientation selectivity in the visual cortex? (
  • For example, presenting two identical objects in rapid succession results in an attenuated fMRI signal in several regions of visual cortex, relative to the rapid presentation of two different objects. (
  • We tested this hypothesis with fMRI and behavioral measures of visual detection sensitivity. (
  • Florian Beissner and Christian Henke, "Methodological Problems in fMRI Studies on Acupuncture: A Critical Review with Special Emphasis on Visual and Auditory Cortex Activations," Evidence-Based Complementary and Alternative Medicine , vol. 2011, Article ID 607637, 7 pages, 2011. (
  • We applied fMRI-based visual field mapping of the central visual field at 3 T in eight controls to compare the pRF properties of the central visual field of a reference condition (stimulus radius: 14°) and two conditions with simulated peripheral visual field defect, i.e., with a peripheral gray mask, stimulating only the central 7° or 4° radius. (
  • 5] used fMRI with traveling wave visual field mapping methods to show that V1 in healthy aging subjects has lower blood-oxygen-level-dependent (BOLD) activity compared to healthy young adults, but found no change in the overall size of V1. (
  • In terms of Brodmann areas, the extrastriate cortex comprises Brodmann area 18 and Brodmann area 19, while the striate cortex comprises Brodmann area 17. (
  • First, we will consider the normal anatomical, physiological, and metabolic development of extrastriate visual cortex, including the prenatal specification of visual areas. (
  • Anatomical evidence of multimodal integration in primate striate cortex. (
  • Given the anatomical and physiological evidence for interactions between vlPFC and visual cortical areas, we hypothesized that vlPFC responses could contribute to the representation and recognition of objects when perceptual judgments are made more difficult by partial occlusion. (
  • In primates, including humans, it has been linked to rapid and unconscious forms of visual processing, such as jumping in fright when you see a stick that looks like a snake, or automatically catching a ball thrown at your face. (
  • Based on straightforward, carefully described anatomy in humans and primates, and informed by advances in cortical physiology over recent years, Miyawaki offers an accessible approach to understanding the multiple visual cortices. (
  • In primates, the extrastriate cortex includes visual area V3, visual area V4, and visual area MT (sometimes called V5), while V1 corresponds to the striate cortex, and V2 to the prestriate cortex. (
  • Also, we quantify the amount of input from ipsi- and contralateral visual fields. (
  • This orderly relationship creates a visuotopic map, whereby V1 neurones on one side of the brain collectively represent the entire contralateral half of the visual field in a gradual and predictable fashion (2,3). (
  • In the cat, the superior colliculus (SC) and cortical areas on the medial bank of posterior middle suprasylvian sulcus (pMS) are regions that when unilaterally damaged result in contralateral visual hemineglect. (
  • Here, we report the consequences of spatiotemporally continuous vs. discontinuous motion on perceptual representations in human ventral visual cortex. (
  • We studied ventral visual cortex, an area of the brain that responds selectively to visual categories (faces, places, and words) in young adults, and that shows little atrophy with age. (
  • In the present study, we focus our attention on ventral visual cortex. (
  • After a resting baseline period of 50 s, the subjects were exposed to a visual stimulus for 20 s, followed by a 50 s resting period in a dimly lit, sound attenuating room. (
  • The visual stimulus was a circular, black and white, alternating checkerboard. (
  • Nine previous positron emission tomography (PET) studies of human visual information processing were reanalyzed to determine the consistency across experiments of blood flow decreases during active tasks relative to passive viewing of the same stimulus array. (
  • Visual response fields (the area of visual space where targets modulate activity) were tested for each neuron in the presence of a background landmark placed at one of four oblique configurations relative to the target stimulus. (
  • Thus, even the smallest stimulus in the visual field will evoke a response from an intricately shaped cluster of thousands of cortical cells distributed over a mean position. (
  • The ability to measure visual field maps in vivo, along with the receptive field properties and stimulus selectivity of the various classes of neurons within these maps, is essential for understanding visual computations. (
  • Experiments have been done to obtain a depth resolved stimulus-specific profile of activation in cat visual cortex. (
  • The results demonstrated two spatially and temporally distinct stages of processing: The first, emerging 70 ms after stimulus onset around the calcarine sulcus, was sensitive to local features only, whereas the second, starting at 130 ms across the occipital and posterior parietal cortices, reflected the global configuration. (
  • However, behavioral research demonstrates that not all visual tasks suffer such capacity limits: The costs of divided attention are minimal when the task and stimulus are simple, such as when searching for a target defined by orientation or contrast. (
  • 2004 ). Furthermore, the emergence of normal binocular visual function depends on interocular inhibition that is mediated by GABAergic inhibitory circuitry in visual cortex (Sengpiel and Vorobyov, 2005 ). (
  • We have shown that both forms of binocular interactions share a common gain control mechanism in striate and extra-striate cortex. (
  • Furthermore, our model fits, revealed different patterns of binocular interaction along the visual cortical hierarchy, particularly in terms of excitatory and suppressive contributions in normal and amblyopic vision. (
  • For the purpose of this review I will focus almost entirely upon the macaque monkey visual system for the reason that it is one of the most understood and best models we have for human vision to date. (
  • 19 used for most analyses) of the tracer biocytin in visual area V4 of six macaque monkeys. (
  • This thesis describes the requirements for a robot that can orient cameras with the same dynamics as macaque monkey eyes as well as a camera system that reproduces macaque visual acuity. (
  • Higher Order Visual Processing in Macaque Extrastriate Cortex. (
  • The researchers targeted inhibitory neurons in the visual cortex to turn them "on," thus silencing that region of the brain. (
  • In the present study, we showed a postnatal sensitive period profile for the modifiability of orientation selectivity in the visual cortex of kittens reared with head-mounted goggles for stable single-orientation exposure. (
  • It has been shown that infusion of an NMDA receptor antagonist to the visual cortex suppresses the expression of orientation selectivity [25] , [26] . (
  • 1.Yoshida, T., Ozawa, K. & Tanaka, S. Sensitivity profile for orientation selectivity in the visual cortex of goggle-reared mice. (
  • Orientation selectivity of neurons in V1 is believed to be central to visual form perception. (
  • New research led by Shigeru Tanaka of the University of Electro-Communications and visiting scientist at the RIKEN Brain Science Institute has shown that the responses of cells in the visual cortex can be 're-tuned' by experience. (
  • Additionally, CO histochemistry revealed sub-compartments of "thick stripes," "thin stripes," and "pale stripes" in the middle layer of the secondary visual cortex (V2), which have been shown to possess distinct connections with V1 and other cortical areas ( Sincich and Horton, 2002 ). (
  • First, adjacent radial columns in the cortex represent partially overlapping regions of the visual field, irrespective of whether these columns are part of the same or different cortical areas. (
  • This rule is not as rigid as the first, as many cortical areas form discontinuous, second-order representations of the visual field. (
  • Removal of afferent input to the somatosensory, auditory, motor or visual cortex results in a marked change of cortical topography. (
  • They suggest this auditory input enables the visual system to predict incoming information and could confer a survival advantage. (
  • In future we will test how this auditory information supports visual processing, but the assumption is it provides predictions to help the visual system to focus on surprising events which would confer a survival advantage . (
  • Our understanding of the visual system has reached new heights over the last decade, with new techniques based on brain metabolism, enzyme histochemistry, immunohistochemistry, voltage-sensitive dyes, and brain imaging having been applied rigorously to the study of the visual cortex (e.g. (
  • Bender, D. B., 1983, Visual activation of neurons in the primate pulvinar depends on cortex but not colliculus, Brain Res . (
  • Firstly, they used whole-brain fluorescence-based axonal tracing by labelling neurons in the right visual cortex of each mouse with GFP and then imaging axonal projections by whole-brain serial two-photon tomography. (
  • The visual system is probably the best understood part of the brain. (
  • These findings demonstrate that a brain prosthetic can produce coherent percepts of visual forms. (
  • Scientists studying brain process involved in sight have found the visual cortex also uses information gleaned from the ears as well as the eyes when viewing the world. (
  • The adoption of the Latin "cortex" to describe the outer gray matter covering of the brain paints this structure as a thin bark or rind enveloping the remainder of the brain. (
  • To study how miR-132 could impact the ability of this brain region to adapt to changing conditions, the scientists temporarily stitched closed one eyelid in mice, to stop the nerve signals from that eye from reaching neurons in the visual cortex. (
  • Structural brain changes have been reported in the insular cortices using quantitative magnetic resonance imaging (MRI) procedures commonly used in research, but rarely applied in clinical practice. (
  • Although gonadal E2 has often been thought to influence these processes, the possibility that central visual processing may be modulated by brain-generated hormone has not been explored. (
  • Recent data show that glaucoma affects extra-retinal vision-related brain structures (including visual cortex) but dynamics and mechanisms of this degeneration remain unclear. (
  • While a wide range of technologies and therapies are being developed to restore vision, a fundamental question still remains unanswered: would the adult visual brain retain a sufficient plastic potential to learn how to see after a prolonged period of abnormal visual experience? (
  • Leopold, David A. 2018-01-08 00:00:00 Human area Prostriata is a small, unstudied portion of the visual brain set deep in the calcarine sulcus, next to V1. (
  • We survey recent measurements of human visual field maps, describe hypotheses about the function and relationships between maps, and consider methods to improve map measurements and characterize the response properties of neurons comprising these maps. (
  • There is debate whether adaptation arises within the cortex or is inherited from the earlier stages in the visual pathway (e.g. visual thalamus or retina). (
  • Next, the researchers sought to learn more about how the visual cortex modulates the reflexes. (
  • This is the first demonstration that vestibular activation modulates human visual cortex excitability. (
  • However, the superior colliculus did not disappear with the development of the cortex in mammals. (