What does the term “neural impulse” refer to?

The term "neural impulse" specifically refers to a brief electrical charge that travels down an axon. This process, known as action potential, involves a rapid change in the electrical potential across a neuron's membrane, which propagates the signal along the axon to communicate with other neurons or muscles. The intensity and speed of this impulse are critical for the effective transmission of signals in the nervous system, enabling responses to stimuli.

The other options, while related to neural activity, do not accurately describe what a neural impulse is. For instance, a sustained electrical charge across multiple neurons pertains more to the overall electrical activity of a network rather than a single event. The overall activity of the nervous system encompasses much more than just a single impulse and includes various integrative processes and interactions among multiple types of neural activity. Lastly, a type of chemical reaction in synapses refers to neurotransmission rather than the electrical nature of a neural impulse itself. Thus, the definition of a neural impulse is best captured by the description of a brief electrical charge that travels down an axon.