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II. Neurophysiology and Perception > RGCs and Amacrines (M2) > Flashcards

RGCs and Amacrines (M2) Flashcards

1
Q

What type of neurotransmitter does AI amacrine cells release? 1. What are these cells involved in? 2

A
  1. GABA

2. lateral inhibition

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2
Q

What are the visual symptoms that a patient with multiple sclerosis can present with?

A
  1. dec VA
  2. reduction in visual fields
  3. sudden-onset diplopia
  4. pupillary defects
  5. color vision defects
  6. Uhthoff’s sign
  7. Pulfrich’s stereo phenomenon
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3
Q

Where do starburst amacrines with cell bodies in the GCL stratify in?

A

ON sublamina

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4
Q

Is the synapse from AII amacrine cells onto ON cone bipolar cells sign-conserving or -inverting? 1. What is the connection like? 2

A
  1. conserving

2. gap junctions

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5
Q

How many different types of amacrine cells are there?

A

20-40

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6
Q

What is the process of action potentials jumping node to node to increase speed called?

A

saltatory propagation

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7
Q

How many midget bipolar cells are connected to a foveal midget RGC? 1. What does this setup gear the vision towards? 2

A
  1. one

2. high spatial resolution

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8
Q

Where are the voltage-gated sodium channels located that lead to saltatory propagation?

A

Nodes of Ranvier

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9
Q

For midget RGCs what is the relative cell body size? 1. Dendrites branching? 2. Stratification type? 3. Percent of total RGCs? 4

A
  1. medium
  2. small
  3. ON or OFF sublamina of IPL
  4. 75-80%
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10
Q

Do midget or parsol RGCs exhibit center-surround antagonism?

A

both

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11
Q

What is the ratio of amacrine:bipolar synapses for parasol RGCs? 1. Midget RGCs? 2

A
  1. 70:30

2. 50:50

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12
Q

What do AI amacrine cells have roles in?

A
  1. amplifying rod-mediated signals

2. mediating the receptive field surround in RGCs during scotopic conditions (light more apparent)

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13
Q

What is the dendritic spread amount for small amacrine cells? 1. Medium? 2. Wide-field? 3

A
  1. less than 300 um
  2. between 300 and 500 um
  3. greater than 500 um
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14
Q

What percentage of the foveal RGCs are midget? 1. Periphery RGCs? 2

A
  1. 95%

2. 45%

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15
Q

For parasol RGCs what is the relative cell body size? 1. Dendrites branching? 2. Stratification type? 3. Percent of total RGCs? 4

A
  1. large
  2. large
  3. ON or OFF sublamina of IPL
  4. 5-10%
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16
Q

Do amacrine cells have graded potentials or action potentials?

A

action potentials

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17
Q

Do midget or parasol RGCs have a more sustained response to light onset or offset? 1. Which have more transient response? 2

A
  1. midget RGC

2. parasol RGC

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18
Q

Where are amacrine cells located?

A
  1. INL

2. GCL (“displaced” amacrine cells)

19
Q

How do rod bipolars connect with RGCs?

A

no direct synaptic connections. Piggy-back into cone system via AII amacrines and onto their bipolars

20
Q

Do parasol or midget RGCs receive input from more cones?

A

parasol

21
Q

Do parasol RGCs display convergence or divergence along the path of a signal? 1. What does this lead to? 2

A
  1. convergence

2. greater spatial summation than midget RGCs

22
Q

Why are action potentials needed in retinal ganglion cells?

A

graded potentials decay gradually with distance from the point of initiation

23
Q

What type of neurotransmitter do wide-field amacrine cells usually use? 1. What do mono-stratified wide-field amacrines mediate? 2

A
  1. GABA

2. lateral inhibition (for center-surround)

24
Q

What are the major functions of amacrine cells?

A
  1. provide feedback inhibition to bipolar cells
  2. provide feedforward inhibition to RGCs
  3. visual processing
25
Q

What are the dopaminergic amacrine cells that can send a process up into the OPL called?

A

interplexiform cells

26
Q

Where do starburst amacrines with cell bodies in the INL stratify in?

A

OFF sublamina

27
Q

During the daytime, what neurotransmitter is released more frequently? 1. What does this do to AII amacrine cells? 2.

A
  1. dopamine

2. closes gap junctions between AII amacrines and cone ON bipolars (preventing ON bipolar saturation)

28
Q

What type of amacrine cells are involved in rod-driven retinal circuitry?

A
  1. AI

2. AII

29
Q

What is so unique about the dendrites of amacrine cells?

A

they can be presynaptic and postsynaptic

30
Q

What do OFF parasol RGCs receive input from? 1. ON parasol RGCs? 2

A
  1. multiple diffuse flat bipolars

2. multiple diffuse bipolars (not sure if flat or invaginating)

31
Q

How many rod bipolar cells do AI amacrine cells receive input from? 1. Where do they provide output? 2

A
  1. 1000

2. to same bipolar cells (negative feedback loop)

32
Q

What is the Pulfrich Effect due to?

A

difference in conduction velocity between the right and left optic nerves

33
Q

For bistratified RGCs what is the relative cell body size? 1. Dendrites branching? 2. Stratification type? 3. Percent of total RGCs? 4

A
  1. small
  2. large
  3. ON and OFF sublamina of IPL
  4. 5-10%
34
Q

What type of neurotransmitter do narrow-field amacrine cells usually use? 1. How many sublamina of the IPL do each of these stratify in? 2. What do these types of cells mediate? 3

A
  1. glycine
  2. 2 or more
  3. vertical inhibition
35
Q

What neurotransmitters do starburst amacrine cells contain?

A
  1. acetylcholine

2. GABA

36
Q

What are the three most common RGCs?

A
  1. midget
  2. parasol
  3. small-bistratified RGCs
37
Q

Do starburst amacrine cells have a sustained or transient response? 1. Do they have center-surround (and ON or OFF)? 2. What are their circuits mostly involved in? 3

A
  1. transient
  2. yes (both ON and OFF)
  3. motion detection
38
Q

What is the inhibition done by amacrine cells thought to contribute to?

A
  1. inhibitory surrounds of RGC receptive fields (enhance center-surround)
  2. make RGC responses to light stimuli more transient
39
Q

For dopaminergic amacrine cells, what causes that cells to release dopamine?

A
  1. light stimulation

2. circadian rhythm (high during day)

40
Q

What is the most frequent cause of demyelination in the CNS? 1. What are the first symptoms these patients usually have? 2

A
  1. multiple sclerosis

2. visual deficiencies

41
Q

Is the synapse from AII amacrine cells onto OFF cone bipolar cells sign-conserving or -inverting? 1. What is the connection like? 2

A
  1. inverting

2. glycine release (hyperpolarize)

42
Q

What does the closing of AII amacrine cell gap junctions by dopamine lead to in the IPL?

A
  1. switch from scotopic to photopic vision

2. alters gain of retinal circuits

43
Q

What are the two major neurotransmitters in amacrine cells (inhibitory or excitatory)?

A
  1. GABA (inhibitory)

2. glycine (inhibitory)

II. Neurophysiology and Perception (24 decks)

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