Here is a drawing of some presynaptic inputs to a neuron and

Here is a drawing of some presynaptic inputs to a neuron and the recordings made from the postsynaptic neuron when different combinations of presynaptic neurons fire. Explain why you see the response that you do in each of the four recordings.

Solution

A. Ex1 is not able to cause action potential taht cold reach threshold potential. therefore, a complete action potential cannot take place. It is able to depolarize a little but enough to reach the threshold value.

B. when a little depolarization is caused by Ex1, if one more Ex1 is applied before repolarization, it would reach the threshold value and fire an action potential.

C. Ex2 also exerts similar effects like Ex1. therefore, Ex2 alone can not cause action potential. But when it is applied along with Ex1, the conjugated effects of both Ex1 and Ex2 results in firing an action potential.

D. Int causes the neuron to hyperpolarize. Int has antagonistic effect to Ex1. therefore, combined application would nullify the hyperpolarization effect of Int and depolarization effect of Ex1.