• Our understanding of the link between neural activity and perception remains incomplete. (biorxiv.org)
  • We will describe data-analysis techniques to reconstruct receptive field properties of neural populations, and extend them to visual field maps and clusters within human and macaque visual cortex. (visionsciences.org)
  • Next, we extend conventional stimulus-referred notions of the receptive field to neural-referred properties, i.e. cortico-cortical receptive fields that capture the information flow between visual field maps. (visionsciences.org)
  • Furthermore, we will consider how these neural properties change with the state of chronic visual deprivation due to damage to the visual system, and in subjects with severely altered visual input due to prism-adaptation. (visionsciences.org)
  • The unusual case of a man who regained his sight after 40 years of blindness allows researchers to examine the neural and behavioral effects of losing visual experience on the establishment and maintenance of visual system function in humans. (nature.com)
  • My primary interest is to understand how sensorimotor experience in early life influences - for better or worse - the formation and maturation of functional neural circuits in the cerebral cortex. (duke.edu)
  • We have also obtained information regarding the degree of integration of neural circuitry that shape stimulus selectivities of high-order neurons based on the input from low-order neurons within the visual cortex. (nii.ac.jp)
  • Prior knowledge about objects determines neural color representation in human visual cortex. (uva.nl)
  • Neural basis of visual body perception and self-other distinction. (mpg.de)
  • To identify the neural generators of each effect, we examined crossmodal responses to lateralized sounds in visually responsive cortex of 22 patients using electrocorticographic recordings. (mit.edu)
  • To test whether lateralized and nonlateralized components of crossmodal ERPs emerged from common or distinct neural generators, we compared responses throughout visual cortex. (mit.edu)
  • Visual electrodes responded to both contralateral and ipsilateral sounds with a contralateral bias, suggesting that previously observed laterality effects do not emerge from a distinct neural generator but rather reflect laterality-biased responses in the same neural populations that produce phase-resetting responses. (mit.edu)
  • Given these several uses of visually perceived motion, it is unsurprising that many species have evolved hard-wired neural mechanisms to extract motion as a primitive feature of the visual world [1]. (cam.ac.uk)
  • In this issue, a thorough characterization of such a subject shows that he had instant sight for identification of simple shapes like a circle or triangle, with interesting abnormalities and a need for learning about more complicated visual objects, and almost completely spared motion perception. (nature.com)
  • The primary visual cortex (V1) is located in and around the calcarine fissure in the occipital lobe. (wikipedia.org)
  • In mammals, it is located in the posterior pole of the occipital lobe and is the simplest, earliest cortical visual area. (wikipedia.org)
  • Recent functional magnetic resonance imaging (fMRI) work shows that the number of objects is maintained by representations in the inferior intraparietal sulcus (IPS) along dorsal parietal cortex, whereas the resolution of these maintained objects is subserved by the superior IPS and the lateral occipital complex (LOC). (scirp.org)
  • These areas overlap with recently-discovered, retinotopically-organized visual field maps (VFMs) spanning the IPS (IPS-0/1/2/3/4/5), and potentially maps in lateral occipital cortex, such as LO-1/2, and/or TO-1/2 (hMT+). (scirp.org)
  • Other fMRI studies have implicated early VFMs in posterior occipital cortex, suggesting that visual areas V1-hV4 are recruited to represent information in VWM. (scirp.org)
  • In the absence of visual input, occipital ("visual") brain regions respond to sound and spoken language. (jneurosci.org)
  • Auditory-driven phase reset and ERP responses in visual cortex displayed similar topography, revealing significant activity in pericalcarine, inferior occipital-temporal, and posterior parietal cortex, with maximal activity in lateral occipitotemporal cortex (potentially V5/hMT+). (mit.edu)
  • The eye has many features of a camera, beginning with the cornea and ending with the occipital (visual) cortex. (medscape.com)
  • Here, we performed two-photon population calcium imaging in L2/3 primary visual cortex (V1) of headfixed mice performing a visual detection task while simultaneously activating specific groups of neurons using targeted two-photon optogenetics during low contrast visual stimulation. (biorxiv.org)
  • Moreover, the behavioural effects depended on overall performance: when the task was challenging for the mouse, V1 activity was more closely linked to performance, and cortical stimulation boosted perception. (biorxiv.org)
  • At the smallest scale, the receptive field is a property of individual neurons and summarizes the region of the visual field where visual stimulation elicits a response. (visionsciences.org)
  • Saccades differentially modulate human LGN and V1 responses in the presence and absence of visual stimulation. (mpg.de)
  • Previous studies have demonstrated an increased activity when processing unpredicted visual stimulation in V1. (gla.ac.uk)
  • There is a vigorous debate as to whether visual perception and imagery share the same neuronal networks, whether the primary visual cortex is necessarily involved in visual imagery, and whether visual imagery functions are lateralized in the brain. (ox.ac.uk)
  • Orientation selectivity (OS) of neuronal responses is considered to be fundamental for visual perception of contours. (jneurosci.org)
  • Journal Article] patial range and laminar structures of neuronal correlations in the cat primary visual cortex. (nii.ac.jp)
  • A seizure is an episode of neurologic dysfunction caused by abnormal neuronal activity that results in a sudden change in behavior, sensory perception, or motor activity. (medscape.com)
  • A seizure results when abnormal neuronal firing manifests clinically by changes in motor control, sensory perception, behavior, or autonomic function. (medscape.com)
  • For example, in the event that these neuronal discharges are confined to the visual cortex, the seizure manifests itself with visual phenomena. (medscape.com)
  • The visual cortex of the brain is the area of the cerebral cortex that processes visual information. (wikipedia.org)
  • The visual cortex receives its blood supply primarily from the calcarine branch of the posterior cerebral artery. (wikipedia.org)
  • Other studies, however, provide strong support for the idea that skilled actions such as grasping are not affected by pictorial illusions 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. (wikipedia.org)
  • Cerebral Cortex , 26 (4), 1401-1408. (uva.nl)
  • Cerebral Cortex , 26 (5), 1986-1996. (uva.nl)
  • Previous studies of global brain hypoxia ischemia have primarily focused on injury to the cerebral cortex and to the hippocampus. (cdc.gov)
  • Neurons in the visual cortex fire action potentials when visual stimuli appear within their receptive field. (wikipedia.org)
  • Moreover, we propose a simple and effective network model of response to visual stimuli in rodents that might help in investigating network dysfunctions of pathologic visual information processing. (nih.gov)
  • This information is processed and passed down to V5/MT where all stimuli are integrated, specific neurons determining specific perceptions, such as upward motion or forward motion. (hi-beam.net)
  • These perceptions can be tricked - cells adapt to motion stumuli and in the absence of that stimuli, produce the opposite perception. (hi-beam.net)
  • Affective blindsight refers to the residual visual ability of patients with damage to the primary visual cortex (V1, striate cortex ) to react reliably to the emotional valence of stimuli presented to their blind visual fields and whose presence and properties they are unable to report. (scholarpedia.org)
  • In these cases, however, the deficit of visual awareness is remarkably different from that shown by blindsight patients and arises at later stages of stimulus processing that are most likely related to the ability to orient attention toward stimuli presented in a portion of the space, rather than to a defect directly due to visual perception (Driver & Mattingley, 1998). (scholarpedia.org)
  • Consistent with this, only a small fraction of thalamocortical neurons was binocular in vivo across visual stimuli and cortical projection layers. (bvsalud.org)
  • The dorsal stream begins with V1, goes through Visual area V2, then to the dorsomedial area (DM/V6) and medial temporal area (MT/V5) and to the posterior parietal cortex. (wikipedia.org)
  • 1991). Organization of visual inputs to the inferior temporal and posterior parietal cortex in macaques. (scirp.org)
  • Most commonly individuals with PCA exhibit a progressive, dramatic and relatively selective decline in higher visual processing and other posterior cortical functions. (ucl.ac.uk)
  • Goodale and Milner, 1992), it has been suggested that separate parietal (dorsal), occipitotemporal (ventral) and primary visual (posterior) forms of PCA exist (Galton et al. (ucl.ac.uk)
  • However, in a study of 523 patients with Alzheimer's disease at a single specialist centre, a visual presentation (also labelled posterior cortical atrophy) was reported in 5% of the cohort (Snowden et al. (ucl.ac.uk)
  • Odor quality coding and categorization in human posterior piriform cortex. (mpg.de)
  • Our results thus help to reconcile contradictory findings about the involvement of primary sensory cortex in behavioural tasks, suggesting that the influence of cortical activity on behaviour is dynamically reassigned depending on the demands of the task. (biorxiv.org)
  • The area of the visual cortex that receives the sensory input from the lateral geniculate nucleus is the primary visual cortex, also known as visual area 1 (V1), Brodmann area 17, or the striate cortex. (wikipedia.org)
  • The primary visual cortex is the most studied visual area in the brain. (wikipedia.org)
  • 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. (wikipedia.org)
  • The primary visual cortex is divided into six functionally distinct layers, labeled 1 to 6. (wikipedia.org)
  • The average number of neurons in the adult human primary visual cortex in each hemisphere has been estimated at 140 million. (wikipedia.org)
  • γ Band plays a key role in the encoding of visual features in the primary visual cortex (V1). (nih.gov)
  • Selective deficit of mental visual imagery with intact primary visual cortex and visual perception. (ox.ac.uk)
  • In both patients the calcarine cortex with the primary visual area was bilaterally intact. (ox.ac.uk)
  • ii) visual imagery deficits can occur when the primary visual cortex is intact and (iii) the left temporal lobe plays an important role in visual mental imagery. (ox.ac.uk)
  • F. Yildirim and H. BOYACI, "Spatial pattern of activity in primary visual cortex can be modulated by distance perception based on binocular stereo cues," 2011, vol. 40, p. 105, Accessed: 00, 2020. (metu.edu.tr)
  • Electroencephalogram (EEG) studies using the Contralateral Delay Activity (CDA) paradigm have revealed that cortical representations of VWM are at a minimum loosely organized like the primary visual system, such that the left side of space is represented in the right hemisphere, and vice versa. (scirp.org)
  • In the primary visual cortex (V1), orientation-selective neurons can be categorized into simple and complex cells primarily based on their receptive field (RF) structures. (jneurosci.org)
  • SIGNIFICANCE STATEMENT Simple and complex cells, two classes of principal neurons in the primary visual cortex (V1), are generally thought to be equally selective for orientation. (jneurosci.org)
  • In vision, error signals have been found in the primary visual cortex (V1). (gla.ac.uk)
  • 1 2 3 4 5 6 7 Because of this projection abnormality, the primary visual cortex receives-in addition to the normal input from the contralateral hemifield-abnormal input from the ipsilateral hemifield. (arvojournals.org)
  • Using viral-mediated monosynaptic circuit tracing in macaque primary visual cortex (V1), we show that V1 neurons sending FF projections to area V2 receive monosynaptic FB inputs from V2, but not other V1-projecting areas. (bvsalud.org)
  • This paper offers a theory for the origin of direction selectivity (DS) in the macaque primary visual cortex, V1. (bvsalud.org)
  • From the LGN, the signals continue to the primary visual cortex, where further visual processing takes place. (medscape.com)
  • And yet, some perceptual tasks can still be solved when sensory cortex is silenced or removed, suggesting that cortical activity may not always be essential. (biorxiv.org)
  • Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. (wikipedia.org)
  • To the extent perception is sustained, it may rely on sensory representations and to the extent perception is discrete, centered on perceptual updating, it may rely on frontoparietal representations. (iucc.ac.il)
  • One patient showed pure visual mental imagery deficits in the absence of imagery deficits in other sensory domains as well as in the motor domain, while the other patient showed both visual and tactile imagery deficits. (ox.ac.uk)
  • Attention and sensory signals in human visual cortex / David Heeger. (nih.gov)
  • Perception of our sensory environment is actively constructed from sensory input and prior expectations. (gla.ac.uk)
  • Firstly, the presence of internal generative models for the visual environment, secondly feedback connections which project prediction signals of the model to lower cortical processing areas to interact with sensory input, and thirdly prediction errors which are produced when the sensory input is not predicted by feedback signals. (gla.ac.uk)
  • One assumption of active perception frameworks is that predictive signals can update to new retinotopic locations of V1 with sensory input. (gla.ac.uk)
  • The perception of illusory motion signifies the engagement of an internal model as a moving token is internally constructed from the sensory input. (gla.ac.uk)
  • He specialized in the primate visual system and revolutionized scientists' understanding of sensory processing and pattern recognition. (princeton.edu)
  • Visual working memory capacity in retinotopic cortex: Number, resolution, and population receptive fields. (scirp.org)
  • Frontal influences on human retinotopic visual cortex revealed by combining TMS with fMRI and psychophysics. (mpg.de)
  • This thesis investigates the ability of active perception to redirect predictive signals to new retinotopic locations with saccades. (gla.ac.uk)
  • The dorsal stream, sometimes called the "Where Pathway" or "How Pathway", is associated with motion, representation of object locations, and control of the eyes and arms, especially when visual information is used to guide saccades or reaching. (wikipedia.org)
  • More recently, Goodale and Milner extended these ideas and suggested that the ventral stream is critical for visual perception whereas the dorsal stream mediates the visual control of skilled actions. (wikipedia.org)
  • Balint syndrome appears to be perceptual-motor dysfunction that affects the heteromodal cortex of bilateral dorsal occipitoparietal areas. (msdmanuals.com)
  • Using subcellular channelrhodopsin-2-assisted circuit mapping in mouse visual cortex, we compared feedforward (FF) or feedback (FB) cortico-cortical (CC) synaptic input to cells projecting back to the input source (looped neurons) with cells projecting to a different cortical or subcortical area. (elifesciences.org)
  • The name "striate cortex" is derived from the line of Gennari, a distinctive stripe visible to the naked eye that represents myelinated axons from the lateral geniculate body terminating in layer 4 of the gray matter. (wikipedia.org)
  • 2011). Temporal dynamics of encoding, storage, and reallocation of visual working memory. (scirp.org)
  • We hypothesize that DS is initiated in feed-forward LGN input, in the summed responses of LGN cells afferent to a cortical cell, and it is achieved through the interplay of 1) different visual response dynamics of ON and OFF LGN cells and 2) the wiring of ON and OFF LGN neurons to cortex. (bvsalud.org)
  • The proposed theory includes a complete analysis of how stimulus features such as SF and TF interact with ON/OFF dynamics and LGN-to-cortex wiring to determine the preferred direction and magnitude of DS. (bvsalud.org)
  • For example, in the inferior temporal cortex (IT), a neuron may fire only when a certain face appears in its receptive field. (wikipedia.org)
  • The ventral stream begins with V1, goes through visual area V2, then through visual area V4, and to the inferior temporal cortex (IT cortex). (wikipedia.org)
  • Throughout his career, Gross studied neurons in the inferior temporal cortex of the brain, analyzing their visual functions as they relate to perception and learning. (princeton.edu)
  • We describe a method that reconstructs population receptive field (pRF) properties in human visual cortex using fMRI. (visionsciences.org)
  • We used fMRI to study the emergence of "visual" cortex responses to sound and spoken language in blind children and adolescents. (jneurosci.org)
  • Adaptation-induced changes in the temporal-frequency tuning and direction selectivity of cat visual cortical cells were studied. (cambridge.org)
  • These results suggest that crossmodal phase reset and ERP responses previously found to reflect spatial and temporal facilitation in visual cortex may reflect the same underlying mechanism. (mit.edu)
  • This normal projection of visual fibers from the retina is severely disrupted in albinism, where the line of decussation is shifted into the temporal retina. (arvojournals.org)
  • These receptive fields are organized into visual field maps, where neighboring neurons process neighboring parts of the visual field. (visionsciences.org)
  • The four talks in the symposium will cover topics that include the reorganization of visual cortex in blindness, studies of cortical response in children with amblyopia, the normal development of population receptive fields in visual cortex, and the effect of early cortical damage on visual development. (visionsciences.org)
  • 2009). Visual field maps, population receptive field sizes, and visual field coverage in the human MT+ complex. (scirp.org)
  • The visual system includes the eyes, connecting pathways through to the visual cortex, and other parts of the brain (see the image below). (medscape.com)
  • However, the computational processes within a visual field map do not have to coincide with perceptual qualities. (visionsciences.org)
  • Indeed most perceptual functions are associated with multiple visual field maps and even multiple cortical regions. (visionsciences.org)
  • It has been shown that visual illusions such as the Ebbinghaus illusion distort judgements of a perceptual nature, but when the subject responds with an action, such as grasping, no distortion occurs. (wikipedia.org)
  • Top-down modulation in human visual cortex predicts the stability of a perceptual illusion. (uva.nl)
  • The same holds true for studies that investigate perceptual recognition of emotions in the absence of stimulus awareness in neurological populations with lesions to brain areas that are not primarily visual. (scholarpedia.org)
  • The human lateral geniculate nucleus (LGN) of the visual thalamus is a key subcortical processing site for visual information analysis. (bvsalud.org)
  • Each hemisphere's V1 receives information directly from its ipsilateral lateral geniculate nucleus that receives signals from the contralateral visual hemifield. (wikipedia.org)
  • 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. (wikipedia.org)
  • Only activation of groups of cells with similar tuning to the relevant visual stimulus led to a measurable bias of detection behaviour. (biorxiv.org)
  • Targeted photostimulation revealed signatures of centre-surround, predominantly inhibitory and like-to-like connectivity motifs in the local network which shaped the visual stimulus representation and partially explained the change in stimulus detectability. (biorxiv.org)
  • Different stimulus conditions were compared to assess the sensitivity and specificity of the procedure for the detection of the misrouting of visual projections in albinism. (arvojournals.org)
  • Affective blindsight in cortically blind persons thus presents the clearest case of non-conscious emotion perception because, when visual parameters like luminance are carefully controlled, the patients literally cannot see nor visually acknowledge the presence of a stimulus. (scholarpedia.org)
  • The organization of the visual system can be described at different spatial scales. (visionsciences.org)
  • Interestingly, the differential synaptic tuning correlated well with the spatial organization of synaptic input: the inhibitory visual RF in complex cells was more elongated in shape than its excitatory counterpart and also was more elongated than that in simple cells. (jneurosci.org)
  • In the cortex (e.g. [2-4]), and even the retina [5], of primates, cells are found that respond selectively according to direction of motion. (cam.ac.uk)
  • Because of the great interindividual variability of the projection abnormality, studies of the contribution of the abnormally projecting retina to visual perception must be preceded by the localization of the abnormality. (arvojournals.org)
  • Visual processing and, ultimately, visual fields begin in the retina. (medscape.com)
  • Our results support the existence of FF-FB loops in primate cortex, and suggest that FB can rapidly and selectively influence the activity of incoming FF signals. (bvsalud.org)
  • Before these questions can be addressed, it is vital to determine whether a distinct visual field location is actually affected by the projection abnormality. (arvojournals.org)
  • Our findings suggest that early in life, human cortex has a remarkably broad computational capacity. (jneurosci.org)
  • Several theories of hierarchical computation ascribe the bulk of the computational work of the cortex to looped FF-FB circuits between pairs of cortical areas. (bvsalud.org)
  • 2) BB modulation depends on excitatory-inhibitory interplay in the cortex, while NB modulation is because of entrainment to the thalamic drive. (nih.gov)
  • Journal of Experimental Psychology: Human Perception and Performance, 35, 1359-1367. (scirp.org)
  • In other words, to visualize data effectively, we must follow design principles that are derived from an understanding of human perception . (interaction-design.org)
  • Using locally designed and constructed experiment systems capable of recording simultaneously from tens of neurons, we have conducted neurophysiological studies on early and mid-stage visual areas in mammalian visual cortex. (nii.ac.jp)
  • This abnormal visual field representation makes albinism a promising model to examine cortical self-organization in humans, and it is important to understand how and to what extent visual function of the abnormal cortical visual field representation is preserved. (arvojournals.org)
  • We find that "visual" cortex responses to sound increase between 4 and 17 years of age. (jneurosci.org)
  • Over time vision might eliminate these non-visual responses in sighted children, whereas they are maintained in children who are blind. (jneurosci.org)
  • Responses of human visual cortex to uniform surfaces. (mpg.de)
  • Two patients with brain damage from closed head injury were submitted to tests of mental imagery in the visual, tactile, auditory, gustatory, olfactory and motor domains, as well as to an extensive testing of cognitive functions. (ox.ac.uk)
  • This symposium will feature four talks that apply functional brain imaging to the study of both visual development and visual disorders. (visionsciences.org)
  • We conclude that in the absence of visual input, spoken language colonizes the visual system during brain development. (jneurosci.org)
  • Precise and reliable visual field diagnostics is of crucial importance when diagnosing progression in eye diseases or evaluating rehabilitation after brain lesions. (bmj.com)
  • Split brain: Divided perception but undivided consciousness. (uva.nl)
  • The Split-Brain phenomenon revisited: A single conscious agent with split perception. (uva.nl)
  • While many past studies, including studies of visual perception and the visual areas of the brain, have examined how changes in overall contrast affect perception, these results suggest that our visual system responds to the gradient of contrast differences rather than to overall levels of contrast. (elifesciences.org)
  • A new study has shown that monkeys detect transient external pulses delivered to the highest echelons of visual cortex in a way that depends on concomitant visual inputs. (mit.edu)
  • Many visual field maps exist, suggesting that every map contains a unique representation of the visual field. (visionsciences.org)
  • CVDs) are the most common X-linked genetic disorder visual activities, and they might also be excluded from in humans. (who.int)
  • This notion relates the visual field maps to the idea of functional specialization, i.e. separate cortical regions are involved in different processes. (visionsciences.org)