Ganglion cells Flashcards
What is the analogy between cat and monkey ganglion cells?
Monkey parasol (M) cells-> cat alpha/Y cells Monkey midget (P) cells-> cat beta/X cells
What types of response to stimuli do ganglion cells have?
Transient or sustained.
Explain transient/sustained response.
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).
What type of response do alpha/Y/M cells have?
transient.
What feature in cat ganglions were not initially observed in monkeys?
cat Y cells were thought to sum input nonlinearly.
What’s the cardinal feature of a ganglion cell?
Whether it sums input linearly or nonlinearly.
Do Y cells do spatial or chromatic opponency?
Spatial, but sometimes they can have chromatically pure centers by only having M/L cones.
Explain Y cell signature experiment.
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.
Do X/Y cells sum linearly/nonlinearly?
X cells linear. Y cells nonlinear.
What happens with nonlinear response?
A frequency doubling response. one when light bar enters, one when leaves. Y cell signature.
Who argues the Y cell signature doesn’t exist in monkeys?
Kaplan&Shapley.
What are ganglion cells that aren’t X or Y?
W cells. Some contain melanopsin.
Where do alpha cells send their axons to?
Some to LGN, most to SC.
Explain rodieck&watanabe’s experiment.
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.
Explain crook’s experiment.
Stick dextram in SC, attach fluorochrome. The cells they observe look like Rodieck&watanabe cells, but they also are obv M ganglions.