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Neurobiology > Lecture 17 > Flashcards

Lecture 17 Flashcards

1
Q

The peripheral retina is specialized for __, whereas the fovea is specialized for __.

A

high sensitivity; high resolution

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2
Q

Explain the regional differences in retinal structure and function

A

(butterfly shape)
VERY densely packed cones in the center (fovea)
cones quickly decrease as rods quickly increase
rods then gradually decrease as cones stay at constant low density

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3
Q

where is there higher cone density?

A

ONLY the fovea (center)

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4
Q

where is there no cones or rods?

where is there no rods?

A 
optic disk (where the optic nerve exits)
very center of the fovea (all cones)
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5
Q

in the periphery, convergence of signals from __ increases __; in the fovea, non-convergence of signals from __ increases __

A

rods; sensitivity; cones; resolution

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6
Q

ratio of photoreceptors to bipolar cells and then to ganglion cells in periphery vs fovea

A

fovea = 1:1, periphery is more

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7
Q

in light, absorption of photons leads to __ (__ channels close)
in dark, Vm ~ __, there is high g__, dark current

A

hyperpolarization of Vm; Na

-35mV; high gNa

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8
Q

bipolar cells have __ receptive fields

A

center-surround

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9
Q

2 classes of bipolar cells (__ and __) based on response to light have different type of __ receptors.

A

OFF-center and ON-center; glutamate

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10
Q

OFF-center bipolar cells are __, whereas ON-center bipolar cells are __

A

hyperpolarizing; depolarizing

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11
Q

does the cone response to light spot in center look like the response of an ON-center bipolar cell or an OFF-center bipolar cell?

A

OFF-center

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12
Q

ON/OFF bipolar and retinal ganglion cells’ response to light vs dark in center… what changes?

A

they flip. on-center in light spot looks like off-center in dark spot

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13
Q

in light, photoreceptors __ and __

A

hyperpolarize and stop releasing glutamate

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14
Q

what type of glutamate receptors do OFF-center bipolar cells have? what about ON-center bipolar cells?

A 
OFF = Ionotropic channels
ON = mGluR
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15
Q

which is closest to the source of light? photoreceptors, horizontal cells, bipolar cells, amacrine cells, or retinal ganglion cells?

A

retinal ganglion cells!

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16
Q

ON-center bipolar cells have __ metabotropic __

so when transmitter stop being released, the bipolar cells is __ and goes on to __ the ON-center retinal ganglion cell

A

inhibitory metabotropic GluRs; depolarized; depolarize

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17
Q

OFF-center bipolar cells have __ ionotropic __, so when transmitter stops being released the cell is __ and __ OFF-center retinal ganglion cell

A

excitatory ionotropic GluRs; hyperpolarized; hyperpolarizes

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18
Q

photoreceptors are inhibitory? releasing glutamate in the absence of light and then stopping in light?

A

?

19
Q

in the dark, photoreceptors are __ and __ (do/do not) release glutamate (vice versa for in light)

A

depolarized; do release glutamate!

20
Q

photoreceptors are __ when they are activated/ when they see light

A

hyperpolarized

21
Q

glutamate excites __ bipolars via __ and inhibits __ bipolars via __

A

off-center; ionotropic (GluR) receptors; on-center; metabotropic GluR

22
Q

how did they find out how ganglion cells code patterns of light falling on the retina?

A

controlled the different patterns of light shown to the eye and recorded response from electrode in an axon in the optic nerve

23
Q

ganglion cells have __ center-surround receptive fields

2 classes of ganglion cells:

A

antagonistic

on-center cells and off-center cells

24
Q

how the firing of retinal ganglion cells in response to light moving across the receptive field

A

?

25
Q

retinal ganglion cells are sensitive to __ levels of illumination

A

differences in levels of illumination

26
Q

horizontal cells are responsible for __

A

antagonistic effects of “surround”

27
Q

horizontal cells are __, release __

A

inhibitory; release GABA

28
Q

in default state (dark), photreceptors in the surround are depolarized and releasing glutamate which __ horizontal cells which __
in light, photoreceptors are hyperpolarized and glutamate release is __ , horizontal cells are __ and stop __

A

excites; release GABA

decreased; hyperpolarized; releasing GABA

29
Q

horizontal cells are __ergic and their response is the __ (same as or opposite of) photoreceptors

A

GABAergic; opposite of

30
Q

information from the left and right visual fields is received by __; info from the left visual field is received by the __ portion of the right retina and the __ portion of the left retina (nasal or temporal)
vice versa for the right visual field..

A

both left and right retinas; temporal; nasal

31
Q

__ (nasal/temporal) portions (and the retinal ganglion cells) of each retina cross the optic chiasm (__)
__ (nasal/temporal) portions (and the retinal ganglion cells) of each retina do not cross (__)

A

nasal; contralateral

temporal; ipsilateral

32
Q

left visual field goes through the __ (right/left) optic tract
right visual field info goes through the __ (right/left) optic tract

A

right; left

33
Q

optic tracts occur __ (before/after) the optic chiasm

A

after

34
Q

retina -> optic nerves -> optic chiasm -> optic tracts -> __ -> __

A

LGN (lateral geniculate nucleus of the thalamus)

V1 (primary visual cortex)

35
Q

each LGN has __ layers, each layer having input from __ (one eye or both eyes)

A

6; one eye

36
Q

some LGN layers are necessary from perception of __, some for the perception of __

A

movement; color

37
Q

going up the LGN layers, they vary by whether or not the eye is

A

contralateral or ipsilateral

38
Q

magnocellular layer = __
fast/slow? transient/sustained?__ sensitive, __ insensitive
large/small receptive field?
can tell you __

A

large cells; fast; transient; motion sensitive; color-insensitive; large RF; where and how fast

39
Q

parvocellular layer =
fast/slow? transient/sustained? __ sensitive
can tell you __

A

small cells: slow: sustained; color-sensitive; what/object recognition

40
Q

konicellular layers = lie __

project to __

A

in between the main layers

layer 2/3 in V1

41
Q

left and right eye inputs from retinal project to which layers?

A

all types

42
Q

receptive field of LGN neurons are __ (like unlike) retinal ganglion cell receptive fields
LGN neurons have a base level of firing without stimulation

A

like

43
Q

V1 is also known as the __ or __

A

primary visual cortex or striate cortex

44
Q

LGN axons terminate most heavily in which layer of V1?

A

4C

Neurobiology (16 decks)

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