Primary visual cortex
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The visual cortex divides into five different areas (V1 to V5) based on function and structure.
Researchers have recorded cells in this region responding to differences in color, spatial frequency, moderately complex patterns, and object orientation.[5] V2 sends feedback connections to V1 and has feedforward connections with V3-V5. Bilateral lesions can cause complete cortical blindness and can sometimes be accompanied by a condition called Anton-Babinski syndrome, which is when a patient is blind but denies having any visual deficit.[10][11]
Cortical blindness can result from any disruption or damage to the normal architecture of the visual cortex.
Complex cells, which occur in V1-V3, are like simple cells in that they respond to edges and orientations, but they do not appear to represent a single receptive field. 7th ed. Unilateral lesions can lead to homonymous visual field deficits or, if small, scotomas. One pathway, referred to as the ventral stream for its path along the ventral portion of the brain, passes from V1 to the extrastriate areas and on to the inferior part of the temporal lobe; it is thought that the ventral stream primarily carries information involved with object form and recognition.
[PubMed: 1374953]
DeAngelis GC, Ohzawa I, Freeman RD. Receptive-field dynamics in the central visual pathways. [PubMed: 30825453]
Goodale MA. Transforming vision into action. Also, complex cells respond preferentially to movement in specific directions.
The term striate cortex comes from its histological appearance in which the white-matter tracts of afferent fibers within lamina IV (the outer line of Baillarger) is just visible to the naked eye and is known as the line of Gennari 1,2.
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The primary visual cortex is supplied mainly by the calcarine artery but can also receive blood from the parieto-occipital artery and posterior temporal artery3.
Afferent fibers
Input to the primary visual cortex is from the lateral geniculate body via the optic radiation.
Efferent fibers
Extending from the primary visual cortex is the visual association (extra striate) cortex which occurs throughout the rest of the occipital lobe and in certain sections of the parietal and temporal lobes.
A second pathway, the dorsal stream, travels from V1 to the extrastriate areas and then to the posterior parietal lobe; it is thought to be involved with perceiving motion and spatial relationships between objects in the visual field. V1 responds to simple visual components such as orientation and direction. Notably, layer 4 is the location that receives information from the lateral geniculate.
[PubMed: 30844182]
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Disclosure: Prasanna Tadi declares no relevant financial relationships with ineligible companies.
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From there, it is carried in a tract often called the optic radiation, which curves around the wall of the lateral ventricle in each cerebral hemisphere and reaches back to the occipital lobe.V1 is divided up into six distinct layers, each comprising different cell types and functions. The visual areas of the brain are a great example of just how complex the brain is, for they have probably been studied more than any other brain region, yet there are still many unanswered questions about exactly how they work to create the rich experience we call visual perception.
References (in addition to linked text above):
Purves D, Augustine GJ, Fitzpatrick D, Hall WC, Lamantia AS, McNamara JO, White LE. Neuroscience.
Simple cells, which are found mostly in V1, respond to specific types of visual cues, such as the orientation of edges and lines. Nat Neurosci. 2018 Jan 03;97(1):164-180.e7. Instead, they respond to the summation of several receptive fields that become integrated from many simple cells.