In neurons, summation of two or more inputs of the same type that occur at different times
summation of postsynaptic membrane potentials that occur close to one another in time, but not simultaneously
Synaptic addition of local responses to two stimuli close together in time to produce a response greater that that seen with either separately.
Temporal summation is an effect generated by a single neuron as way of achieving action potential. Summation occurs when the time constant is sufficiently long and the frequency of rises in potential are high enough that a rise in potential begins before a previous one ends. The amplitude of the previous potential at the point where the second begins will algebraically summate, generating a potential that is overall larger than the individual potentials.