Question

What is known as an axon terminal forming a synapse on a dendrite and firing several action potentials in quick succession, resulting in multiple EPSPs in the postsynaptic cell that can be added together to create a greater depolarization of the postsynaptic membrane?

a. Temporal summation.
b. Spatial summation.
c. Presynaptic inhibition.
d. Postsynaptic inhibition.

Answer 1

Temporal summation occurs when multiple action potentials from one neuron overlap in time, leading to an increased depolarization of the postsynaptic membrane, and possibly an action potential if the threshold is reached. It differs from spatial summation, where multiple neurons send signals to different areas on the postsynaptic neuron simultaneously.

Step-by-step explanation:

The phenomenon described is known as temporal summation. It refers to the process where several action potentials arrive in quick succession at the axon terminal, causing multiple excitatory postsynaptic potentials (EPSPs) that add up. When these EPSPs overlap in time, they can cause a larger depolarization of the postsynaptic membrane, increasing the likelihood of reaching the threshold voltage to trigger an action potential.

Temporal summation contrasts with spatial summation, which happens when multiple presynaptic neurons simultaneously send signals to different places on the postsynaptic neuron. Both forms of summation are critical for the integration of synaptic inputs and play a role in determining whether a neuron will fire an action potential, effectively filtering important signals from random 'noise' within the nervous system.