What is the electrical activity level called when a neural signal travels from pre- to postsynaptic neurons?

The electrical activity level referred to when a neural signal travels from pre- to postsynaptic neurons is known as the action potential. This phenomenon occurs when a neuron reaches a sufficient level of depolarization, causing a rapid change in membrane potential. During an action potential, sodium channels open, allowing sodium ions to flow into the neuron, which leads to a spike in voltage and the propagation of the signal along the axon.

The action potential is an all-or-nothing response—once the threshold is reached, it will occur propagating down the axon to transmit information to the next neuron. This process is vital for communication within the nervous system as it enables rapid signaling over long distances. The action potential is distinct from other electrical states such as resting potential, which describes the stable, inactive state of a neuron, or graded potential, which refers to changes in membrane potential that vary in magnitude and are not sufficient to trigger an action potential. Threshold potential relates specifically to the point of depolarization needed to initiate the action potential, rather than describing the signal itself as it travels between neurons.