Temporal summation

Temporal summation: (1) A single EPSP results in a small depolarization of the membrane but is not strong enough to produce an action potential. (2) and (3) Several EPSPs can combine to reach the activation threshold. Spatial summation: (4) Depolarization can also reach the activation threshold when several EPSPs occurring at different synapses are added together. Temporal summation of IPSPs: (5) and (6) The summation of IPSPs results in hyperpolarizations that take the neuronal membrane potential away from the activation threshold.