Visual System Function: Central Vision Processing Flashcards
LGN Layers 3-6
Parvocellular
*Contains axons of P-type RGCs, have small fields, and respond w/ sustained firing
LGN Layers 1,2
Magnocellular
*Contain axon from M-type RGCs, have large receptor fields, and respond to stimulation w/ transient spiking
Layer IVCa
Receives axons from Layers 1,2 of LGN; have oval shaped receptor fields that are orientation selective
=>projects to Layer IVB
Layer IVCb
Receives axons from LGN Layers 3-6
Cells are binocular; are orientation AND direction sensitive
*Allows for the analysis of motion
=>projects to Layer III
Layer III (Primary Visual Cortex)
Receives axons from intralaminar neurons in LGN
P-IB (Parvocellular interblob channel)
Allows for detection of shape via orientation of receptive fields
- Are found in b/w the blobs of Layer III
- Are binocular & insensitive to wavelength
Blob Channel
Allows for analysis of color via wavelength sensitive, monocular cells
Dorsal Stream of Extrastriate Visual Cortex
Layer IVB M-channel neurons project to…
- Area MT- shows directional tuning and responds to movement
- Area MST- Responds to complex motions (Rotation, linear motion)
Ventral Stream of Extrastriate Visual Cortex
Blob and interblob neurons of Layer IVC project thru…
- Area V4- Large receptive fields that contribute to color analysis and perception
- IT Areas- Respond to colors and highly specific shapes
Achromatopsia
Lesion in V4 that results in partial/complete loss of color vision
Prospagnosia
Lesion in IT areas where pts. are unable to identify the faces of people
Fusiform gyrus
Contains the major face recognition area
Strabismus in children
Leads to suppressed input from weak eye; results in abnormal development of the visual cortex
*Treat by patching the eye/surgically repairing it
Retinal disparity
Mechanism for near-field perception
Far-field depth perception
Depth cues are
Size Interposition Linear perspective Light and shadow Motion parallax
