Excitatory postsynaptic potential

Larger EPSPs result in greater membrane depolarization and thus increase the likelihood that the postsynaptic cell reaches the threshold for firing an action potential.

[3][4] In the neuromuscular junction of vertebrates, EPP (end-plate potentials) are mediated by the neurotransmitter acetylcholine, which (along with glutamate) is one of the primary transmitters in the central nervous system of invertebrates.

In fact, even without stimulation of the presynaptic cell, a single vesicle will occasionally be released into the synapse, generating miniature EPSPs (mEPSPs).

Bernard Katz pioneered the study of these mEPSPs at the neuromuscular junction (often called miniature end-plate potentials[6]) in 1951, revealing the quantal nature of synaptic transmission.

[citation needed] Quantal analysis refers to the methods used to deduce, for a particular synapse, how many quanta of transmitter are released and what the average effect of each quantum is on the target cell, measured in terms of amount of ions flowing (charge) or change in the membrane potential.

In studies of hippocampal long-term potentiation (LTP), figures are often given showing the field EPSP (fEPSP) in stratum radiatum of CA1 in response to Schaffer collateral stimulation.

[8] The Schaffer collaterals make excitatory synapses onto these dendrites, and so when they are activated, there is a current sink in stratum radiatum: the field EPSP.