Visual [3] Flashcards
Which of the 5 types of retinal neurons make APs?
Only the ganglion cells
- all other retinal cells communicate by graded changes in membrane potential which alter the rate of exocytosis of NTs in graded fashion
- have donut RFs
Photoreceptor cells are (pick one) depolarized/hyperpolarized by light, resulting in more/less NT release
hyperpolarized
less
Photoreceptors release which NT?
Glutamate
but Bipolar cells can either be excited (OFF center) or inhibited (ON center) by glutamate
Bipolar cells can either be excited (____center) or inhibited (____center) by glutamate
Off
On
Bipolar cells always make (pick one) excitatory/inhibitory synapses on ganglion cells
excitatory
If glutamate from the photoreceptor excites the bipolar cell, then shining light on the photoreceptor will do what to the ganglion cell?
INHIBIT (off center ganglion cell)
Light shown in the center
Excites which bipolar cell?
Light → hyperpolarize → Excites On center bipolar cell → depolarize → release more Glu → increase firing rate of on center ganglion cells
Light shown in the surrounding area (not centered)
Excites which bipolar cell?
Light → hyperpolarize → release less glu → horizontal cells are less excited → release less GABA → center photoreceptors release more GLU → EXCITES OFF CENTER BIPOLAR CELLS → depolarize → release more Glu → increase firing rate of off center ganglion cells
Which pathway is responsible for spatial vision, which for object vision?
Dorsal pathway: spatial vision
- parietal lobe
Ventral pathway: object vision
- temporal love
Critical period
period of time when the connections can be altered by visual experience
(kittens vs adult cats)
- deprivation can silence cortex and cortical cells lose virtually all connections to the deprived eye
- defect is in the cortex, not the retina
