Lecture 8, Vision Flashcards
Fovea
region of retina with highest visual acuity
info from fovea makes half of fibers in optic nerve
Optic disc
region where axons leaving retina gather for form the optic nerve
no photoreceptors, small blind spot
light is going to be projected in through the lens back to the fovea, picked up by photoreceptos
Retinal fields
area of visual field that is projected onto the retina
Rods
more numerous than cones by ratio of 20:1
poor spatial and temporal resolution of visual stimuli
main function is low level lighting vision
far more sensitive than cones to produce vision without color
Cones
less numerous
lots in the fovea
relatively high spatial and temporal resolution
detect colors
Receptive field
portion of field where light causes exitation or inhibition of teh cell
Action potential and Photoreceptors/bipolar cells
they do NOT use action potential
use passive electrical conduction and neurotransmitters, ends up being graded potential
Pathway for vision
Retinal ganglion cells send axon to optic nerve
some crossing in optic chiasm
goes down optic tract, to LGN nucleus
LGN goes to visual cortex via optic radiations
Fibers from left hemiretinas
end up in left optic tract
Fibers from right hemiretinas
right optic tract
Nasal retinal fibers
cross over in the optic chiasm
Rogue fibers in visual pathway
minority of fibers bypass LGN to enter the superior colliculus
form extrageniculate visual pathways, which project ot pretectal area and superior colliculus, and association cortex
Pretectal area
pupillary light reflex
Superior colliculus
directing visual attention towards stimuli
Meyer’s loop
carrying info from inferior retina/superior visual field
are located in the temporal lobe
