vision Flashcards
visual cortex: explain the concept of functional specialisation of the visual cortex
where is the primary visual cortex (striate cortex)
along calcarine sulcus in occipital lobe
what causes shape of primary visual cortex
myelinated fibre of optic radiation projecting into it
representation of primary visual cortex
large area representing macula; superior projects below calcarine fissue, inferior projects above; right hemifield from both eyes project to left of cortex, left hemifield to right of cortex
how is primary visual cortex organised
as columns with unique sensitivity to visual stimulus of a particular orientation, so depth perception
what intersperse each other in primary visual cortex
right eye and left dominant columns
what is damage to primary visual cortex usually due to
stroke
what does damage to primary visual cortex lead to
contralateral homonymous hemianopia with macula sparing
what does the macula receive dual blood supply from
posterior cerebral arteries on both sides (hence macular sparing common)
diagram of macular sparing homonymous heminaopia
slide 7
what is the area around the primary visual cortex in occipital lobe
extrastriate cortex
function of extrastriate cortex
converts basic visual information, orientation and position into complex information
dorsal pathway of extrastriate cortex
primary visual cortex -> posterior parietal cortex
function of dorsal pathway of extrastriate cortex; consequence of damage
motion detection by visually-guided action; damage causes motion blindness
ventral pathway of extrastriate cortex
primary visual cortex -> inferiotemporal cortex
function of ventral pathway of extrastriate cortex; consequence of damage
object representation, face recognition, with detailed fine central vision and colour vision; damage may cause cerebral achromatopsia
