Visual Striate Cortex Flashcards
general path of visual system
lateral geniculate nucleus (LGN, in the thalamus), striate cortex (layer IVC and outside layer IVC), extrastriate cortex
retinotopy
map of visual space such that neighboring cells in the retina feed into neighboring cells in their target structure. high resolution info that doesnt converge takes up more space in the cortex
contralateral vs. ipsolateral
contralateral: info goes to the opposite side of the brain than it was recieved from
ipsolateral: info stays on the same side
separation of visual information
parallel processing
M-type retinal ganglion cells
large receptive fields (center-surround), very sensitive to light, important for detection of movement,
P-type retinal ganglion cells
small receptive fields (center-surround and color-opponent), some respond to color, important for detection of shape
Non-M-non-P type retinal ganglion cells
not well studied, important for color detection, color-opponent
organization of the LGN
P-type -> parvocellular
M-type -> magnocellular
nonM-nonP -> koniocellular
striate cortex
LGN inputs to the striate cortex, ocular dominance columns (parvocellular and magnocellular cells in IVC), cytochrome oxidase blobs (koniocellular)
outside layer IVC in the striate cortex
binocular receptive fields: originally separate info from two eyes is projected onto each other in layer III
orientation selectivity: accomplished through simple cells which respond to lines of light by having multiple cells with center-surround receptive fields with adjacent centers (ON center, OFF surround
direction selectivity: response to movement
complex cells: respond to particular orientation of visual stimulus, simple cell activation depolarizes and fires onto complex cells, no OFF
dorsal and ventral streams
dorsal: “where” pathway, M-type cell info, navigation, directing eye movements, motion perception
ventral: “what” pathway, identification, special region for faces
