Excitatory postsynaptic potentials (EPSP) are characterized by what change?

Excitatory postsynaptic potentials (EPSPs) are characterized by a positive voltage change in the postsynaptic neuron. This occurs when neurotransmitters bind to receptors on the postsynaptic membrane and lead to the opening of sodium ion channels. As sodium ions (Na+) flow into the neuron, the inside of the neuron becomes less negative (or more positive) relative to the outside. This depolarization moves the membrane potential closer to the threshold for generating an action potential, increasing the likelihood that the neuron will fire an action potential.

This positive voltage change is crucial for the processes of synaptic transmission and neuronal communication. By facilitating depolarization, EPSPs play a key role in the integration of synaptic signals, helping to determine whether a neuron will respond to incoming stimuli. Thus, the characteristic of a positive voltage change is fundamental to understanding how excitatory signals influence neuronal activity.