Retinal Physiology

Question 1

PRs are slightly depolarized relative to a typical neuron. What is the resting membrane potential of a PR?

Answer 1

-50mV

Question 2

In the dark, what 2 things happen to PRs?

Answer 2

1. Release glutamate

2. Depolarized

Question 3

In the light, what 2 things happen to PRs?

Answer 3

1. No glutamate released

2. Hyperpolarized

Question 4

What % of rhodopsin must be bleached to have a critical number of sodium channels closed?

Answer 4

10%

Question 5

PRs show what type of potential?

Answer 5

Graded potential - degree of PR hyperpolarization is related to intensity of stimulus

Question 6

PRs synapse with what 2 inhibitory cells in the OPL?

Answer 6

1. Bipolar Cells

2. Horizontal Cells

Question 7

What two cells send retinal info horizontally? Are these cells excitatory or inhibitory?

Answer 7

Horizontal and amacrine cells

- inhibitory

Question 8

Lateral connections provide feedback transmission of information via what pathway?

Answer 8

Centrifugal pathway (from gang. cells to PRs)

Question 9

Horizontal cells receive input from what cell?

Answer 9

One or more PR

Question 10

Horizontal cells send information to what cell?

Answer 10

Bipolar cells - may also be innervated directly by other PRs

Question 11

What inhibitory neurotransmitter do horizontal cells release in response to DEPOLARIZATION of PRs?

Answer 11

Gaba

Question 12

H1 Horizontal cells primarily receive input from what PR?

Answer 12

M and L Cones

Question 13

This type of horizontal cell regulates adaptation and spatial responses of cones and bipolar cells

Answer 13

H1

Question 14

T/F: H1 cells connect to cones in its dendritic field and rods at its most distal end

Answer 14

True

Question 15

H2 horizontal cells receive input from all 3 types of cones. Do they connect to rods?

Answer 15

No, do not connect to rods

Question 16

What 2 types of cells show a graded response?

Answer 16

PRs and Horizontal Cells

Question 17

PRs and Horizontal Cells both HYPERPOLARIZE in response to light. What is this called?

Answer 17

Sign-conserving synapses

Question 18

This is the region of visual space that makes a neuron change its firing under the presence of a certain visual stimulus.

Answer 18

Retinal receptive field

Question 19

A bipolar dendrite synapses with what 2 cells?

Answer 19

PRs and Horizontal cells

Dendrite = BPH, dicks

Question 20

A bipolar axon synapses with what 2 cells?

Answer 20

Ganglion, Amacrine Cells

Axon = BAG

Question 21

What neurotransmitter is released from bipolar cells?

Answer 21

Glutamate

Question 22

Bipolar cells receive extensive synaptic feedback from what cell?

Answer 22

Amacrine cells

Question 23

What are the 4 kinds of bipolar cells?

Answer 23

1. Rod bipolar
2. Midget bipolar
3. Diffuse bipolar
4. S-cone bipolar

Question 24

This type of bipolar cells does not contact ganglion cells directly. They’re mediated by amacrine or cone bipolar cells

Answer 24

Rod bipolar cells (only 1 kind)

Question 25

In the central/mid-peripheral retina, this bipolar cell contacts only 1 cone. In the peripheral retina, this cell has input from more than 1 cone.

Answer 25

Midget bipolar cell (M or L input)

Question 26

In the central retina, this bipolar cell contacts about 5 neighboring cones, and in peripheral retina about 10-15.

Answer 26

Diffuse bipolar cell

Question 27

This type of bipolar cell is a short wavelength cone.

Answer 27

S-cone bipolar cell

Question 28

Bipolar cells generate what type of potential?

Answer 28

Graded potential

Question 29

Bipolar cells were the first to display ___ ____

Answer 29

Spatial antagonism

Question 30

If the bipolar cell depolarizes in response to less glutamate, what type of cell is this?

Answer 30

on-center cell - excited by light - releases glutamate

Question 31

If the bipolar cell hyperpolarizes in response to less glutamate, what type of cell is this?

Answer 31

off-center cell - inhibited by light - doesn't release gluta.

Question 32

On-center bipolar cells synapse with ganglion cells in what layer of the IPL?

Answer 32

Inner sublayer (invagination synapse in

Question 33

Off-center bipolar cells synapse with ganglion cells in what layer of the IPL?

Answer 33

Outer sublayer

Question 34

The center response in bipolar cells comes directly from?

Answer 34

PRs

Question 35

The surround response comes indirectly from?

Answer 35

Horizontal cells

Question 36

What neurons were the first in the visual system to fire action potentials and generate transient responses?

Answer 36

Amacrine Cells

Question 37

The short and sweet response of Amacrine cells help do what 2 things?

Answer 37

1. Code movement | 2. Detect Change

Question 38

This is when the ganglion cells are always active, even when not stimulated. Sends signals from 5-40/sec.

Answer 38

Spontaneous Activity/ Maintained discharge

Question 39

Ganglion cells produce what type of potential?

Answer 39

Full action potentials

Question 40

On/Off center bipolar cells synapse with

Answer 40

On/Off center ganglion cells, respectively.

Question 41

On/Off center midget bipolar cells synapse with ?

Answer 41

On/Off center midget ganglion cells (parvo cells/p-cells)

Question 42

On/Off center diffuse bipolar cells synapse with?

Answer 42

On/Off center parasol ganglion cells (magno cells/M-cells)

Question 43

Midget (parvo) GCs are found where?

Answer 43

in the fovea

Question 44

What layers of the LGN do p-cells project to?

Answer 44

Parvocellular layers

Question 45

These ganglion cells are color sensitive, have high spatial resolution, poor temporal resolution and a sustained response to light

Answer 45

P-Cells, Midget Ganglion cells

Question 46

Input for the m-cells come from what cells?

Answer 46

Rods

Question 47

What layers of the LGN do m-cells project to?

Answer 47

Magnocellular layers

Question 48

This type of ganglion cell has good temporal resolution, is sensitive to motion and has a transient response to light.

Answer 48

Parasol ganglion cells (M-cells)

Question 49

The opposite effects of light on the center and surround is called:?

Answer 49

Spatial Antagonism/Lateral inhibition

Question 50

What 2 cells cause an action potential?

Answer 50

Amacrine and Ganglion

Question 51

What layer of the LGN do small, bistratified ganglion cells project to?

Answer 51

Konio layer