Answer:
temporal summation
Explanation:
Temporal summation occurs when stimuli are applied to the same axon in rapid succession. These back to back stimuli cause overlapping EPSPs that sum. Temporal summation requires the buildup of neurotransmitter released by a single presynaptic end bulb two or more times in rapid succession that does not allow the postsynaptic neuron's membrane potential to return to the resting potential. The resultant postsynaptic potentials sum. A typical EPSP lasts about 15 msec. Therefore, temporal summation occurs when the second release of neurotransmitters occurs soon after the first one so that the postsynaptic neuron does not acquire resting potential.