A revised method for generation of unitary postsynaptic potentials for quantal analysis in the hippocampus.

For quantal analysis of excitatory postsynaptic potentials (EPSPs) in hippocampal CA3 neurons, a method was devised to evoke trains of unitary EPSPs at intended intervals and to control the number of unitary EPSPs composing each train at will. The amplitudes of the first EPSPs in EPSP trains evoked with this method were measured. From the mean and variance of the EPSP amplitudes, the mean number of quanta (m) released by a single impulse and the mean amplitude of EPSPs induced by individual quanta (q) were estimated in a standard solution and in a high calcium solution.