Visual System 2 Flashcards
Alternating bands of V1
-Eye specific columns
Ocular Dominance Columns
The eye specific layers in LGN are traded for eye specific columns in
V1
Most cells in each column respond to input from
Only 1 eye
Improves what the eye sees
Visual cortex
Which cells in the visual cortex see dots?
Ganglion cells, LGN cells, 4C cells
Simple cells in the cortex see
Lines
Simple an complex cells are above and below layer
4C
Keep in mind that V1 has a retinotopic map. An edge of this profile is tagged with
Position information
In higher visual regions, this information is interpreted as
Shape and Form
The visual association (secondary) cortex is everything except
V1
The fusiform gyrus is linked to
Recognition
Places are linked to the
Hippocampus
Facial recognition is linked to the
Fusiform gyrus
Arises after damage to the fusiform gyrus
-Thought to require bilateral damage to the Fusiform Face Area
Prosopagnosia
Closed head trauma or bilateral stroke is often responsible for bilateral damage to the
Fusiform Face Area
Patients are unable to recognize people by looking at their faces
Prosopagnosia
Visual acuity is often in tact, but input can not be combined in a meaningful way
Apperceptive Agnosia
Apperceptive agnosia is due to a
V2/V3 lesion
Patient could likely draw a key from memory, but wouldn’t be able to recognize what they drew when challenged later
Apperceptive agnosia
Causes cerebral achromatopsia
V4 lesion
A V5 lesion causes
Akinetopsia (motion blindness)
Static items are visible but disappear once they start moving rapidly
Akinetopsia
Motion can be detected in slow moving objects but direction of movement is obscure
Akinetopsia
