unit 2 review - vision Flashcards
aqueous vs. vitreous
aq
- in front of lens, behind cornea
vit
- behind lens
myopia
near sighted
- too much refraction
- concave lense
direct pathway for light?
1) photo receptors
2) bipolar cells
3) ganglion cells
what are the only retinal cells to fire action potentials?
retinal ganglion cells
there are more — than — in the visual system
more rods than cones
photoreceptors have more — channels?
na leak channels
phototransduction pathway?
1) opsin -> rhodopsin
2) activates transducin
3) activates PDE
4) PDE inhibits cGMP
5) hyperpolarize
calcium feedback pathway?
1) calcium inhibits gualnyl cyclase
2) in hyperpolarize conditions, there is less calcium
3) guanyle cyclase activity increases
4) cGMP increases - Na and Ca channels re-open
what does the optic radiation control?
- contralateral visual field in both eyes
what is the optic radiation?
projection of LGN to the cortex
ON bipolar cell
likes glu - hyp
light = depolarize
OFF bipolar cell
doesnt like glu - dep
light = hyperpolarize
dark on surround, light on center activates
ON bipolar cells - depolarize
light on surround, dark on center
OFF bipolar cells - depolarize
what is V1 receptive field?
bar of light with a particular orientation
what is dorsal secondary area receptive field?
spots of light moving in a particular direction
- motion processing
what is the ventral secondary area receptive field?
biologically significant objects
- form/color processing
bipolar and ganglion cells relationship?
on-center bipolar cells trigger on-center ganglion cells
parvo
- more popular
- smalls RF
- color sensitive
- sustained APs
magno
- less popular
- large RF
- color insensitive
- transient APs
where is the LGN located?
thalamus
input for LGN?
20 retina
80 V1
ipsi in LGN?
2,3,5
magno in LGN?
1,2
where does layer 5 of the LGN project to?
- what is it associated with?
superior colliculus
- eye movement
where does layer 6 of the LGN project to?
- what is it associated with?
LGN
- feedback
what is the dorsal stream?
1) magno LGN
2) 4CA
3) 4B
4) occip and parietal
what is the ventral stream?
1) parvo/conio LGN
2) 4Cbeta
3) 2/3
4) occip and temporal
describe layer 4C
mon vs. bi?
receptive field properties?
- monocular
- dominance columns
- dominance columns run perpendicular to V1 layers
describe layers V1 apart from 4C?
mon vs. bi?
receptive field properties?
- binocular
- orientation and direction
- cortical modules
what columns are located in V1?
what do they aid with?
orientation columns
- form perception
direction columns
- motion perception
cortical modules in v1?
- for analyzing a particular point
- blobs = color processing
what is located in area V5?
- all cells are direction selective
- direction columns
what is located in area MST?
- cells for motion, navigation, motion perception
what is located in area V4?
- color
- orientation selectivity
what is located in IT?
identifying faces
what is layer 6 involved in?
color perception
what factor is responsible for bipolar cell receptive fields?
the type of glutamate receptor on the bipolar cell
what is the direction do the layers of the LGN go?
high to low
what is the second messenger of the phototranduction pathway?
high -> low
optic tract effects what?
the contra lateral visual field
destroying the lens means?
can see far, but not near
when light hits a PR attatched to an OFF bipolar cell?
OFF bipolar cell depolarizes
