A hypothetical postsynaptic neuron has three presynaptic inputs¾X, Y, and Z. When X and Y are stimulated simultaneously, the postsynaptic neuron undergoes an action potential, yet when X and Z are stimulated simultaneously, there is no change in the postsynaptic neuron's potential. What can you tell about neurons Y and Z?
A) Y and Z are both excitatory.
B) Y and Z are both inhibitory.
C) Y is excitatory and Z is inhibitory.
D) Y is inhibitory and Z is excitatory.
E) Not enough information to answer.

Question

Quizplus · Accepted Answer

Since X and Y stimulation together causes an action potential (excitatory), we can conclude that neuron Y is excitatory. Since X and Z stimulation together causes no change in the postsynaptic neuron potential (inhibitory), we can conclude that neuron Z is inhibitory. Therefore, the answer is C, with Y being excitatory and Z being inhibitory.

A Hypothetical Postsynaptic Neuron Has Three Presynaptic Inputs¾X, Y, and Z