visual pathways Flashcards
how can rods join the cone pathways
via amacrine cells
what are the five projections of the optic tracts
dLGN, superior colliculus, accesory optic nuclei, pretectal area, SCN
what do melanopsin retinal ganglion cells do
signal light levels. Pretectal and SCN paths
difference b/w melanopsin containing and rods and cones
depolarize in response to light and lasts as long as the stimulus withough adaptation
efferent limb failure
failure of one pupil to constrict when light is shined in eigher eye, with normal constriction of other pupil
why do you get preserved near response in MLF syndrome
b/c the third nucleus doesnt get gaze command but it does get near response command
deficit seen in LGN lesion
slightly non-corresponding (almost homonymous) deficits due to laminar segregation.
where do you see exactly corresponding visual field deficits
occipital cortex
route of upper field information. Lower field information
through meyer’s loop to lower bank of calcarine fissure. Parietal path to upper bank
Extrastriate lesions: temporal, parietal, occipito-temporal
loss of recognition and memory; visual inattention and neglect; loss of recognition of faces
rule of thumb for localizing lesions: the more homonymous, the more ___ the lesion. The higher in the upper field, the more ___ the lesion
posterior; lateral
