What creates an action potential in a neuron?

An action potential in a neuron is primarily created through the process of depolarization of the neural membrane. When a neuron is stimulated, specific ion channels in the membrane open, allowing sodium ions (Na+) to flow into the cell. This influx of positively charged sodium ions decreases the negativity inside the neuron relative to the outside environment, leading to depolarization. If this depolarization reaches a certain threshold, it triggers a rapid, dramatic change in membrane potential, which constitutes an action potential.

This is a key process in neural communication, as the action potential travels along the axon and initiates neurotransmitter release at the synapse, enabling signal transmission between neurons. The other options do not initiate an action potential: hyperpolarization makes the inside of the neuron more negative and inhibits action potentials; neurotransmitter release occurs as a result of an action potential, not the cause; and repolarization refers to the return of the membrane potential back to its resting state after an action potential has occurred.