Evoked Potentials, Visual
Pattern Recognition, Visual
Magnetic Resonance Imaging
Image Processing, Computer-Assisted
Ocular Physiological Phenomena
Visual Field Tests
Analysis of Variance
Transcranial Magnetic Stimulation
Voltage-Sensitive Dye Imaging
Excitatory Postsynaptic Potentials
Signal Processing, Computer-Assisted
Long-Term Synaptic Depression
Signal Detection, Psychological
Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
Task Performance and Analysis
S100 Calcium Binding Protein G
Retinal Ganglion Cells
Electron Transport Complex IV
Data Interpretation, Statistical
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)
There are different types of blindness, including:
1. Congenital blindness: Blindness that is present at birth, often due to genetic mutations or abnormalities in the development of the eye and brain.
2. Acquired blindness: Blindness that develops later in life due to injury, disease, or other factors.
3. Amblyopia: A condition where one eye has reduced vision due to misalignment or other causes.
4. Glaucoma: A group of eye conditions that can damage the optic nerve and lead to blindness if left untreated.
5. Retinitis pigmentosa: A degenerative disease that affects the retina and can cause blindness.
6. Cataracts: A clouding of the lens in the eye that can impair vision and eventually cause blindness if left untreated.
7. Macular degeneration: A condition where the macula, a part of the retina responsible for central vision, deteriorates and causes blindness.
There are various treatments and therapies for blindness, depending on the underlying cause. These may include medications, surgery, low vision aids, and assistive technology such as braille and audio books, screen readers, and voice-controlled software. Rehabilitation programs can also help individuals adapt to blindness and lead fulfilling lives.
Some common types of vision disorders include:
1. Myopia (nearsightedness): A condition where close objects are seen clearly, but distant objects appear blurry.
2. Hyperopia (farsightedness): A condition where distant objects are seen clearly, but close objects appear blurry.
3. Astigmatism: A condition where the cornea or lens of the eye is irregularly shaped, causing blurred vision at all distances.
4. Presbyopia: A condition that occurs as people age, where the lens of the eye loses flexibility and makes it difficult to focus on close objects.
5. Amblyopia (lazy eye): A condition where one eye has reduced vision due to abnormal development or injury.
6. Strabismus (crossed eyes): A condition where the eyes are misaligned and point in different directions.
7. Color blindness: A condition where people have difficulty perceiving certain colors, usually red and green.
8. Retinal disorders: Conditions that affect the retina, such as age-related macular degeneration, diabetic retinopathy, or retinal detachment.
9. Glaucoma: A group of conditions that damage the optic nerve, often due to increased pressure in the eye.
10. Cataracts: A clouding of the lens in the eye that can cause blurred vision and sensitivity to light.
Vision disorders can be diagnosed through a comprehensive eye exam, which includes a visual acuity test, refraction test, and dilated eye exam. Treatment options for vision disorders depend on the specific condition and may include glasses or contact lenses, medication, surgery, or a combination of these.
1. A false or misleading sensory experience, such as seeing a shape or color that is not actually present.
2. A delusion or mistaken belief that is not based on reality or evidence.
3. A symptom that is perceived by the patient but cannot be detected by medical examination or testing.
4. A feeling of being drugged, dizzy, or disoriented, often accompanied by hallucinations or altered perceptions.
5. A temporary and harmless condition caused by a sudden change in bodily functions or sensations, such as a hot flash or a wave of dizziness.
6. A false or mistaken belief about one's own health or medical condition, often resulting from misinterpretation of symptoms or self-diagnosis.
7. A psychological phenomenon in which the patient experiences a feeling of being in a different body or experiencing a different reality, such as feeling like one is in a dream or a parallel universe.
8. A neurological condition characterized by disturbances in sensory perception, such as seeing things that are not there ( hallucinations) or perceiving sensations that are not real.
9. A type of hysteria or conversion disorder in which the patient experiences physical symptoms without any underlying medical cause, such as numbness or paralysis of a limb.
10. A condition in which the patient has a false belief that they have a serious medical condition, often accompanied by excessive anxiety or fear.
ILLUSIONS IN MEDICINE
Illusions can be a significant challenge in medicine, as they can lead to misdiagnosis, mismanagement of symptoms, and unnecessary treatment. Here are some examples of how illusions can manifest in medical settings:
1. Visual illusions: A patient may see something that is not actually there, such as a shadow or a shape, which can be misinterpreted as a sign of a serious medical condition.
2. Auditory illusions: A patient may hear sounds or noises that are not real, such as ringing in the ears (tinnitus) or hearing voices.
3. Tactile illusions: A patient may feel sensations on their skin that are not real, such as itching or crawling sensations.
4. Olfactory illusions: A patient may smell something that is not there, such as a strange odor or a familiar scent that is not actually present.
5. Gustatory illusions: A patient may taste something that is not there, such as a metallic or bitter taste.
6. Proprioceptive illusions: A patient may feel sensations of movement or position changes that are not real, such as feeling like they are spinning or floating.
7. Interoceptive illusions: A patient may experience sensations in their body that are not real, such as feeling like their heart is racing or their breathing is shallow.
8. Cognitive illusions: A patient may have false beliefs about their medical condition or treatment, such as believing they have a serious disease when they do not.
THE NEUROSCIENCE OF ILLUSIONS
Illusions are the result of complex interactions between the brain and the sensory systems. Here are some key factors that contribute to the experience of illusions:
1. Brain processing: The brain processes sensory information and uses past experiences and expectations to interpret what is being perceived. This can lead to misinterpretation and the experience of illusions.
2. Sensory integration: The brain integrates information from multiple senses, such as vision, hearing, and touch, to create a unified perception of reality. Imbalances in sensory integration can contribute to the experience of illusions.
3. Attention: The brain's attention system plays a critical role in determining what is perceived and how it is interpreted. Attention can be directed towards certain stimuli or away from others, leading to the experience of illusions.
4. Memory: Past experiences and memories can influence the interpretation of current sensory information, leading to the experience of illusions.
5. Emotion: Emotional states can also affect the interpretation of sensory information, leading to the experience of illusions. For example, a person in a state of fear may interpret ambiguous sensory information as threatening.
THE TREATMENT OF ILLUSIONS
Treatment for illusions depends on the underlying cause and can vary from case to case. Some possible treatment options include:
1. Sensory therapy: Sensory therapy, such as vision or hearing therapy, may be used to improve sensory processing and reduce the experience of illusions.
2. Cognitive-behavioral therapy (CBT): CBT can help individuals identify and change negative thought patterns and behaviors that contribute to the experience of illusions.
3. Mindfulness training: Mindfulness training can help individuals develop greater awareness of their sensory experiences and reduce the influence of illusions.
4. Medication: In some cases, medication may be prescribed to treat underlying conditions that are contributing to the experience of illusions, such as anxiety or depression.
5. Environmental modifications: Environmental modifications, such as changing the lighting or reducing noise levels, may be made to reduce the stimulus intensity and improve perception.
Illusions are a common experience that can have a significant impact on our daily lives. Understanding the causes of illusions and seeking appropriate treatment can help individuals manage their symptoms and improve their quality of life. By working with a healthcare professional, individuals can develop a personalized treatment plan that addresses their specific needs and helps them overcome the challenges of illusions.
The amblyopic eye may have reduced visual sharpness and/or abnormal ocular alignment (strabismus). The other eye is generally normal or has better vision. Amblyopia is often present at birth but may not be noticed until the child is a few years old. It can also result from various conditions, such as strabismus, cataracts, or differences in the refractive error of the two eyes (anisometropic amblyopia).
The most common form of amblyopia is anisometropic amblyopia, which occurs when there is a significant difference in the refractive power between the two eyes. This can cause the brain to favor one eye over the other, leading to reduced vision in the amblyopic eye. Amblyopia can be treated with glasses or contact lenses, patching the better eye to force the weaker eye to work harder, or surgery to correct strabismus or anisometropia.
Early detection and treatment are important to prevent long-term visual impairment. However, amblyopia can sometimes persist even after treatment, and it is a leading cause of monocular vision in adults.
Scotoma is a term that was first used in the early 19th century to describe blind spots in the visual field caused by defects in the retina or optic nerve. Over time, the term has been broadened to include any type of blind spot or defect in the visual field, regardless of its cause.
There are several different types of scotomas, including:
1. Homonymous hemianopsia: A condition in which there is a blind spot in one side of both eyes, causing difficulty with recognizing objects and people on that side.
2. Hemianopia: A condition in which there is a blind spot in one half of both eyes, often caused by a stroke or brain injury.
3. Quadrantanopia: A condition in which there is a blind spot in one quarter of both eyes, often caused by a stroke or brain injury.
4. Scanning vision: A condition in which the visual field appears to be scanned or sectioned off, often caused by a brain disorder such as multiple sclerosis.
5. Blind spot scotoma: A condition in which there is a small blind spot in the central part of the visual field, often caused by a lesion in the retina or optic nerve.
Scotomas can have a significant impact on daily life, making it difficult to perform everyday tasks such as driving, reading, and recognizing faces. Treatment options for scotomas depend on the underlying cause and may include prism glasses, vision therapy, or surgery. In some cases, scotomas may be a sign of a more serious condition that requires medical attention.
There are several causes of hemianopsia, including:
1. Stroke or cerebral vasculitis: These conditions can damage the occipital lobe and result in hemianopsia.
2. Brain tumors: Tumors in the occipital lobe can cause hemianopsia by compressing or damaging the visual pathways.
3. Traumatic brain injury: A head injury can cause damage to the occipital lobe and result in hemianopsia.
4. Cerebral palsy: This condition can cause brain damage that leads to hemianopsia.
5. Multiple sclerosis: This autoimmune disease can cause damage to the visual pathways and result in hemianopsia.
Symptoms of hemianopsia may include:
1. Blindness or impaired vision in one side of both eyes.
2. Difficulty recognizing objects or people on one side of the visual field.
3. Inability to see objects that are peripheral to the affected side.
4. Difficulty with depth perception and spatial awareness.
5. Eye movements that are abnormal or restricted.
Diagnosis of hemianopsia typically involves a comprehensive eye exam, including visual acuity testing, visual field testing, and imaging studies such as MRI or CT scans to evaluate the brain. Treatment options for hemianopsia depend on the underlying cause and may include:
1. Glasses or contact lenses to correct refractive errors.
2. Prism lenses to realign the visual image.
3. Visual therapy to improve remaining vision.
4. Medications to treat underlying conditions such as multiple sclerosis or brain tumors.
5. Surgery to repair damaged blood vessels or relieve pressure on the brain.
It is important to note that hemianopsia can significantly impact daily life and may affect an individual's ability to perform certain tasks, such as driving or reading. However, with proper diagnosis and treatment, many people with hemianopsia are able to adapt and lead fulfilling lives.
There are several types of strabismus, including:
* Esotropia: where one eye turns inward toward the nose
* Exotropia: where one eye turns outward away from the face
* Hypertropia: where one eye turns upward
* Hypotropia: where one eye turns downward
* Duane's syndrome: a rare type of strabismus that affects only one eye and is caused by nerve damage.
Strabismus can have both visual and social consequences, including:
* Difficulty with depth perception and binocular vision
* Blurred or double vision
* Difficulty with eye teaming and tracking
* Poor eye-hand coordination
* Social and emotional effects such as low self-esteem, anxiety, and depression.
Treatment options for strabismus include:
* Glasses or contact lenses to correct refractive errors
* Prism lenses to align the eyes
* Eye exercises to strengthen the muscles and improve eye teaming
* Surgery to adjust the position of the muscles that control eye movement.
It is important for individuals with strabismus to receive timely and appropriate treatment to address the underlying cause of the condition and prevent long-term vision loss and social difficulties.
Characteristics: People with cortical blindness may have difficulty recognizing objects, navigating their environment, and perceiving light and colors. They may also experience visual hallucinations or distortions. The blindness can be partial or total, and the degree of vision loss can vary widely.
Causes: Cortical blindness can be caused by a variety of factors, including:
* Stroke or brain injury that damages the visual cortex
* Infections such as meningitis or encephalitis that affect the visual cortex
* Genetic disorders such as retinitis pigmentosa or Leber's congenital amaurosis
* Traumatic brain injury
* Tumors or cysts in the visual cortex
Symptoms: Symptoms of cortical blindness can include:
* Difficulty recognizing objects or faces
* Poor spatial awareness and navigation
* Blurred or distorted vision
* Sensitivity to light or glare
* Visual hallucinations or distortions
* Partial or total loss of vision
Diagnosis: Diagnosis of cortical blindness typically involves a comprehensive eye exam, neurological evaluation, and imaging tests such as MRI or CT scans to identify any underlying causes.
Treatment: There is no cure for cortical blindness, but various therapies and strategies can help improve functional vision and independence. These may include:
* Vision rehabilitation therapy to improve visual function and adapt to new ways of seeing
* Assistive technology such as telescopes or closed-circuit television systems to enhance remaining vision
* Training in mobility and orientation skills
* Compensatory strategies for daily activities
Prognosis: The prognosis for cortical blindness varies depending on the underlying cause and severity of the condition. In some cases, partial recovery of vision may be possible with time and therapy, while in other instances, visual function may remain impaired or stable.
Prevention: Prevention of cortical blindness is not always possible, but early detection and treatment of underlying conditions can help reduce the risk of vision loss. Regular eye exams and monitoring by a neurologist or ophthalmologist can also help identify any changes in vision and potential causes of cortical blindness.
Overall, cortical blindness is a complex and rare condition that requires specialized care and rehabilitation to improve functional vision and independence. With the right therapies and strategies, individuals with cortical blindness can lead fulfilling lives and adapt to their new visual reality.
Some common types of perceptual disorders include:
1. Visual perceptual disorders: These disorders affect an individual's ability to interpret and make sense of visual information from the environment. They can result in difficulties with recognizing objects, perceiving depth and distance, and tracking movement.
2. Auditory perceptual disorders: These disorders affect an individual's ability to interpret and make sense of sound. They can result in difficulties with hearing and understanding speech, as well as distinguishing between different sounds.
3. Tactile perceptual disorders: These disorders affect an individual's ability to interpret and make sense of touch. They can result in difficulties with recognizing objects through touch, as well as interpreting tactile sensations such as pain, temperature, and texture.
4. Olfactory perceptual disorders: These disorders affect an individual's ability to interpret and make sense of smells. They can result in difficulties with identifying different odors and distinguishing between them.
5. Gustatory perceptual disorders: These disorders affect an individual's ability to interpret and make sense of tastes. They can result in difficulties with identifying different flavors and distinguishing between them.
6. Balance and equilibrium disorders: These disorders affect an individual's ability to maintain balance and equilibrium. They can result in difficulties with standing, walking, and maintaining posture.
Perceptual disorders can have a significant impact on an individual's daily life, making it difficult to perform everyday tasks and activities. Treatment for perceptual disorders often involves a combination of sensory therapy, behavioral therapy, and assistive technologies. The goal of treatment is to help the individual compensate for any impairments in sensory processing and improve their ability to function in daily life.
There are several subtypes of agnosia, each with distinct symptoms:
1. Visual agnosia: Difficulty recognizing objects, colors, or shapes.
2. Auditory agnosia: Inability to recognize familiar sounds or voices.
3. Tactile agnosia: Difficulty identifying objects by touch.
4. Olfactory agnosia: Loss of the ability to smell.
5. Gustatory agnosia: Inability to taste or identify different flavors.
6. Hyperagnosia: Excessive sensitivity to stimuli, leading to over-recognition of objects and excessive memory for details.
7. Hypoagnosia: Under-recognition of objects, leading to difficulty identifying familiar items.
Agnosia can be caused by various factors, such as stroke, traumatic brain injury, infections, neurodegenerative diseases (e.g., Alzheimer's disease, Parkinson's disease), and developmental disorders (e.g., autism spectrum disorder). Treatment options depend on the underlying cause of the agnosia and may include rehabilitation therapies, medications, or surgery.
In summary, agnosia is a neurological condition characterized by difficulty in recognizing objects, voices, or other sensory stimuli due to damage to specific areas of the brain. It can affect one or more senses and can be caused by various factors. Treatment options vary depending on the underlying cause of the disorder.
The most common symptoms of albinism include:
* Pale or white skin, hair, and eyes
* Sensitivity to the sun and risk of sunburn
* Poor vision, including nystagmus (involuntary eye movements) and photophobia (sensitivity to light)
* Increased risk of eye problems, such as strabismus (crossed eyes) and amblyopia (lazy eye)
* Increased risk of skin cancer and other skin problems
* Delayed development of motor skills and coordination
* Increased risk of infection and other health problems due to a weakened immune system
Albinism is caused by mutations in genes that code for enzymes involved in the production of melanin. These mutations can be inherited from one or both parents, or they can occur spontaneously. There is no cure for albinism, but there are treatments available to help manage some of the associated symptoms and vision problems.
Diagnosis of albinism is typically made based on a combination of physical examination, medical history, and genetic testing. Treatment may include sun protection measures, glasses or contact lenses to improve vision, and medication to manage eye problems. In some cases, surgery may be necessary to correct eye alignment or other physical abnormalities.
It's important for people with albinism to receive regular medical care and monitoring to ensure early detection and treatment of any associated health problems. With proper care and support, many people with albinism can lead normal, fulfilling lives.
Low vision is not the same as blindness, but it does affect an individual's ability to perform daily activities such as reading, driving, and recognizing faces. The condition can be treated with low vision aids such as specialized glasses, telescopes, and video magnifiers that enhance visual acuity and improve the ability to see objects and details more clearly.
In the medical field, Low Vision is often used interchangeably with the term "visual impairment" which refers to any degree of vision loss that cannot be corrected by regular glasses or contact lenses. Visual impairment can range from mild to severe and can have a significant impact on an individual's quality of life.
Low Vision is a common condition among older adults, with approximately 20% of people over the age of 65 experiencing some degree of visual impairment. However, Low Vision can also affect younger individuals, particularly those with certain eye conditions such as retinitis pigmentosa or other inherited eye disorders.
Overall, Low Vision is a condition that affects an individual's ability to see clearly and perform daily activities, and it is important for individuals experiencing vision loss to seek medical attention to determine the cause of their symptoms and explore available treatment options.
Ocular dominance column
Extrastriate body area
Visual pathway lesions
Boston University CTE Center and Brain Bank
Santiago Ramón y Cajal
Prediction in language comprehension
Dorsolateral prefrontal cortex
Hierarchical temporal memory
Spectro-temporal receptive field
Anna Christina Nobre
Motion silencing illusion
Lists of Canadians
Metabotropic glutamate receptor
Dementia with Lewy bodies
Soma (video game)
Capsule neural network
Human brain development timeline
Kenneth D Harris
Functional Local Input to Layer 5 Pyramidal Neurons in the Rat Visual Cortex
Researchers interested in Visual Cortex | Yale School of Medicine
Cambridge Research Systems - Visual Cortex Phased-Array MRI Coil
A two-photon imaging tale: integration and specialization in mouse visual cortex - Zurich Open Repository and Archive
Unconscious and Conscious Processing of Color Rely on Activity in Early Visual Cortex: A TMS Study | Journal of Cognitive...
Orientation Contrast Sensitivity from Long-range Interactions in Visual Cortex
Temporary Visual Deprivation Causes Decorrelation of Spatiotemporal Population Responses in Adult Mouse Auditory Cortex | eNeuro
Serval - The contributions of sensory dominance and attentional bias to cross-modal enhancement of visual cortex excitability.
Orientation-tuned fMRI adaptation in human visual cortex - Fingerprint - Experts@Minnesota
Representation of Maximally Regular Textures in Human Visual Cortex - Research Repository
Clusters in visual cortex - Visual Neuroscience
Comparison of FMRI measurements in LGN and primary visual cortex with visual deficits in Glaucoma
2202.10157] Conformal models for hypercolumns and the visual V1 cortex
Direction Selectivity In Primary Visual Cortex Using Massive Intracortical Connections
Representation of edges, head direction, and swimming kinematics in the brain of freely-navigating fish | Scientific Reports
Cortical recycling in high-level visual cortex during childhood development<...
Effect of immersive virtual mirror visual feedback on Mu suppression and coherence in motor and parietal cortex in stroke. |...
Uncorrelated neural firing in mouse visual cortex during spontaneous retinal waves | GW Expert Finder
Genetic influence is linked to cortical morphology in category-selective areas of visual cortex - Dimensions
Delay-period activity in frontal, parietal, and occipital cortex tracks noise and biases in visual working memory
A Unified Theory of Early Visual Representations from Retina to Cortex through Anatomically Constrained Deep CNNs | OpenReview
Theory of feature selectivity in rodent primary visual cortex - ELSC | Edmond & Lily Safra Center for Brain Sciences
The formation of hierarchical decisions in the visual cortex. - Royal Netherlands Academy of Arts and Sciences (KNAW)
Relative latency and temporal variability of hemodynamic responses at the human primary visual cortex<...
Visual training with musical notes changes late but not early electrophysiological responses in the visual cortex<...
Structure and function relationships during ocular dominance plasticity in the visual cortex. - Netherlands Institute for...
- We characterized the functional excitatory local input to these 3 cell subtypes in rat primary visual cortex using laser-scanning photostimulation. (nih.gov)
- V2 and later visual areas are sensitive to these features, while primary visual cortex is not (Freeman et al. (essex.ac.uk)
- The second part presents a model for the hypercolumns, which originates from the symplectic model of the primary visual cortex by A. Sarti, G. Citti and J. Petitot, the spherical model of hypercolumns by P. Bressloff and J. Cowan and basic results of the conformal geometry of sphere. (cornell.edu)
- The majority of neurons in primary visual cortex are tuned for stimulus orientation, but the factors that account for the range of orientation selectivities exhibited by cortical neurons remain unclear. (maxplanckneuroscience.org)
- striate cortex. (nih.gov)
- Effect of immersive virtual mirror visual feedback on Mu suppression and coherence in motor and parietal cortex in stroke. (bvsalud.org)
- We investigated the activation pattern of the motor cortex (M1) and parietal cortex during immersive virtual reality (VR)-based mirror visual feedback (MVF) of the upper limb in 14 patients with chronic stroke and severe upper limb hemiparesis and in 21 healthy controls. (bvsalud.org)
- Mu suppression in bilateral M1 and parietal cortex and mu coherence were analyzed. (bvsalud.org)
- The ipsilesional mu coherence between the M1 and parietal cortex in patients with stroke was stronger than controls, regardless of MVF condition (p patients with stroke (p = 0.032). (bvsalud.org)
- Here, we investigated how delay-period activity in frontal and parietal cortex, which is known to correlate with the decline in behavioral memory precision observed with increasing memory load, might relate to diffusion and drift. (timbuschman.com)
- VEHSS identifies the annual prevalence of diagnosed Disorders of the Optic Nerve and Visual Pathways based on the presence of International Classification of Diseases (ICD)-9 and ICD-10 codes in patient claims or electronic health record (EHR) systems. (cdc.gov)
- Diagnosed disorders of the optic nerve and visual pathways include a patient having one or more diagnosis codes indicating one or more of the subgroups listed below. (cdc.gov)
- Disorders of the visual pathway and visual cortex include diagnosis codes indicating disorders of visual pathways and visual cortex. (cdc.gov)
- Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS. (bvsalud.org)
- In many locations, the SNR of this posterior-only coil is more than 2X greater than a typical vendor-provided whole-head 32 channel coil, and allows for fast, high-resolution imaging of the visual cortex, down to 0.75mm isotropic voxel resolution for fMRI, and 0.35mm isotropic resolution for anatomical imaging. (crsltd.com)
- They find that a new method to analyse brain function - based on measuring the phase relationships between the responses in the visual cortex - reveals similar functional clusters during both resting-state and visual field mapping fMRI experiments. (visualneuroscience.nl)
- Previously, these changes have only been conceptualized as excitatory gain increases in sensory cortices for acquired fear-relevant stimuli during associative learning. (unboundmedicine.com)
- The results of opposing CS+ and CS- modulations in sensory cortex reflect predictions of the Rescorla-Wagner model and current neurobiological findings. (unboundmedicine.com)
- The contributions of sensory dominance and attentional bias to cross-modal enhancement of visual cortex excitability. (unil.ch)
- Almost all models of orientation and direction selectivity in visual cortex are based on feedforward connection schemes, where genicu(cid:173) late input provides all excitation to both pyramidal and inhibitory neurons. (neurips.cc)
- Properties of visual cortical neurons are compared in detail to this model and to a classical model of direction selectivity that does not include excitatory corti co-cortical connections. (neurips.cc)
- To address this issue, we used in vivo two-photon calcium imaging to characterize the orientation tuning and spatial arrangement of synaptic inputs to the dendritic spines of individual pyramidal neurons in layer 2/3 of ferret visual cortex. (maxplanckneuroscience.org)
- 1998. Inhibition of long-term potentiation in developing rat visual cortex but not hippocampus by in utero exposure to polychlorinated biphenyls. (cdc.gov)
- insights gained are the possibility that hysteresis underlies visual cortical function, paralleling proposals for short-term memory, and strong limitations on linearity tests that use gratings. (neurips.cc)
- TY - JOUR T1 - Conditioned inhibitory and excitatory gain modulations of visual cortex in fear conditioning: Effects of analysis strategies of magnetocortical responses. (unboundmedicine.com)
- Swallowing occurs when descending excitatory and inhibitory signals from the cortex and subcortex and ascending signals from the oropharyngeal area trigger the central pattern generator in the bulbar reticular formation ( 5 ). (cdc.gov)
- In this study, the contribution of early visual cortex activity to conscious and unconscious chromatic processing was studied using single-pulse TMS in three time windows 40-100 msec after stimulus onset in three conditions: conscious color recognition, forced-choice discrimination of consciously invisible color, and unconscious color priming. (mit.edu)
- We found that conscious perception and both measures of unconscious processing of chromatic information depended on activity in early visual cortex 70-100 msec after stimulus presentation. (mit.edu)
- Our results highlight structural regularity as an important stimulus dimension for distinguishing the early stages of visual processing, and suggest a previously unrecognized role for V3 in the visual form-processing hierarchy. (essex.ac.uk)
- These results are consistent with a model of the differential recruitment of general frontoparietal mechanisms in response to diffusive noise and of stimulus-specific biases in occipital cortex. (timbuschman.com)
- Critically, as a child develops, increases in face and word selectivity are directly linked to decreases in limb selectivity, revealing that during childhood, limb selectivity in ventral temporal cortex is repurposed into word and face selectivity. (princeton.edu)
- Human ventral temporal cortex contains category-selective regions that respond preferentially to ecologically relevant categories such as faces, bodies, places and words and that are causally involved in the perception of these categories. (princeton.edu)
- We discovered that, from young childhood to the teens, face- and word-selective regions in ventral temporal cortex expand and become more category selective, but limb-selective regions shrink and lose their preference for limbs. (princeton.edu)
- In comparison, a subsequent whole-brain regression analysis showed that drift, rather than diffusion, explained the most variance in delay-period activity in lateral occipital cortex. (timbuschman.com)
- Área del LÓBULO OCCIPITAL relacionada con el procesado de la información visual que le llega a través de las VÍAS DE LA VISIÓN. (bvsalud.org)
- The clinical signs and symptoms of seizures depend on the location of the epileptic discharges in the cerebral cortex and the extent and pattern of the propagation of the epileptic discharge in the brain. (medscape.com)
- The first is a survey of important facts and leading problems concerning the applications of differential geometry in studies on the functional architecture of the visual system. (cornell.edu)
- CVDs) are the most common X-linked genetic disorder visual activities, and they might also be excluded from in humans. (who.int)
- Chromatic information is processed by the visual system both at an unconscious level and at a level that results in conscious perception of color. (mit.edu)
- It remains unclear whether both conscious and unconscious processing of chromatic information depend on activity in the early visual cortex or whether unconscious chromatic processing can also rely on other neural mechanisms. (mit.edu)
- Neuropathological lesions involved visual, auditory, and post- and pre-central cortex areas. (cdc.gov)
- Acquired CVDs reflect a problem that occurs anywhere along the visual pathway from the photoreceptors to the visual cortex (5). (who.int)
- A study conducted occurs anywhere along the visual pathway from the pho- among 267 student volunteers in Menofia University toreceptors to the visual cortex ( 5 ). (who.int)
- Magnetocortical steady-state visual evoked fields (ssVEFs) have been shown to vary in amplitude as a function of associative strength. (unboundmedicine.com)
- Evidence of dysfunction in the visual association cortex in visual snow syndrome. (cdc.gov)
- Here we analyze the emergence of such complex response patterns in a simple model of primary vi(cid:173) sual cortex. (nips.cc)
- Data were collected by self-administered questionnaire consisting of: personal characteristics, prior awareness of colour vision defects, difficulties in daily colour vision activities, and visual function. (who.int)