Question

How will an on-center ganglion cell fire if we shine a small but clearly detectable spot of light on the surround of its receptive field?

a. It will fire at its maximum possible firing rate

b. It will go silent: not fire action potentials at all

c. It will slightly increase its firing rate

d. It will slightly decrease its firing rate

e. It will maintain baseline firing rate

Answer 1

Answer. a. It will fire at its maximum possible firing rate

There are two types of bipolar cells, “on”-center and “off”-center. Both receive the glutamate neurotransmitter, but the on-center bipolar cells will depolarize, whereas the off-center bipolar cells will hyperpolarize. Turning on a spot of light in the center of an on-center ganglion cell receptive field produces a burst of electrical activity (an “on response”). Turning the light on in the center of an off-center ganglion cell receptive field has the opposite effect: The spontaneous rate of firing decreases and when the spot of light is turned off, the cell responds with a burst of action potentials (an “off response”).