Mastering A&P Neurophysiology Practice Test 2026 - Free Neurophysiology Practice Questions and Study Guide

Excitatory postsynaptic potentials (EPSPs) play a crucial role in the functioning of neurons during synaptic transmission. When neurotransmitters bind to receptors on the postsynaptic membrane, they typically cause specific ion channels to open, allowing positively charged ions, such as sodium (Na+), to flow into the neuron. This influx of positive ions results in a change in the membrane potential, causing depolarization.

Depolarization refers to the process where the inside of the neuron becomes less negative (or more positive) relative to the outside. As a result, EPSPs bring the membrane potential closer to the threshold needed for triggering an action potential, which is the electrical signal that travels along the axon. Therefore, the nature of EPSPs is inherently excitatory, promoting the likelihood that the neuron will fire an action potential if the depolarization is sufficient.

In contrast, hyperpolarization, maintenance of resting potential, or the direct triggering of action potentials is not the primary role of EPSPs. Hyperpolarization involves an increase in the negativity of the membrane potential, which is contrary to the effect of EPSPs. Maintaining resting potential refers to the stable state of the membrane potential when a neuron is not actively firing, while action potentials