Final answer:
Interneurons exhibit a change in membrane potential that is graded with the intensity of the stimulus. Graded potentials can summate to create an action potential if the threshold is reached.
Step-by-step explanation:
Interneurons respond to neurotransmitter stimulation with a change in membrane potential that is graded with the stimulus intensity. Unlike action potentials that operate on an all-or-none principle, graded potentials vary in size and are directly proportional to the strength of the stimulus.
If the cumulative changes from these potentials reach a certain threshold, an action potential will be triggered, carrying the signal down the neuron.