Ganglion cells Flashcards

1
Q

What is the analogy between cat and monkey ganglion cells?

A
Monkey parasol (M) cells-> cat alpha/Y cells
Monkey midget (P) cells-> cat beta/X cells
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2
Q

What types of response to stimuli do ganglion cells have?

A

Transient or sustained.

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3
Q

Explain transient/sustained response.

A

Transient: Stimulus-> burst of spikes then nothing, burst when turned off.
Sustained: Stimulus-> burst when turned on, slowed down continued fire as long as stimulus (adaptation).

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4
Q

What type of response do alpha/Y/M cells have?

A

transient.

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5
Q

What feature in cat ganglions were not initially observed in monkeys?

A

cat Y cells were thought to sum input nonlinearly.

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6
Q

What’s the cardinal feature of a ganglion cell?

A

Whether it sums input linearly or nonlinearly.

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7
Q

Do Y cells do spatial or chromatic opponency?

A

Spatial, but sometimes they can have chromatically pure centers by only having M/L cones.

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8
Q

Explain Y cell signature experiment.

A

Take the RF of a cell, do a sinusoidal grading that you shift around. One half positive, other half negative. The sum should cancel out. Done by Enroth and Robson.

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9
Q

Do X/Y cells sum linearly/nonlinearly?

A

X cells linear. Y cells nonlinear.

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10
Q

What happens with nonlinear response?

A

A frequency doubling response. one when light bar enters, one when leaves. Y cell signature.

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11
Q

Who argues the Y cell signature doesn’t exist in monkeys?

A

Kaplan&Shapley.

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12
Q

What are ganglion cells that aren’t X or Y?

A

W cells. Some contain melanopsin.

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13
Q

Where do alpha cells send their axons to?

A

Some to LGN, most to SC.

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14
Q

Explain rodieck&watanabe’s experiment.

A

They inject a tracer into SC, it goes to the retina, observe the tracer. Inject die into the cells where you see tracer. They look nothing like M ganglions. They say the cells that send axons to SC are nether M nor P.

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15
Q

Explain crook’s experiment.

A

Stick dextram in SC, attach fluorochrome. The cells they observe look like Rodieck&watanabe cells, but they also are obv M ganglions.

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16
Q

What anatomic feature was used to dismiss homology between alpha cells and M ganglions?

A

The fact that alphas send both to SC and LGN whereas M were thought not to send to SC, but Crook showed that they do.

17
Q

How did Crook show M ganglion cells to br functionally homologous to Y cells?

A

They recorded from the cells that they observed in their experiment to be M cells sending to SC, they observed a frequency doubling response. Shape, light response and axon target are the same, we can say homologous.

18
Q

What’s the small difference between P and X ganglions?

A

RF of X cell has multi cone input. P ganglion has 1 cone.