[Short term synaptic plasticity].

INTRODUCTION

At many chemical synapses, the amount of transmitter released by each action potential can increase or decrease markedly after the onset of specific temporal patterns of activity.

OBJECTIVES

This review focuses on mechanisms and functions of short term presynaptic plasticity that last from milliseconds to minutes. The short term enhancement of neurotransmitter release is due to three calcium dependent presynaptic processes differing in their durations: about one second or less (facilitation), about 30 seconds (augmentation) and several minutes (post tetanic potentiation). These forms of short term potentiation are usually attributed to a transient elevation in presynaptic calcium ions (Ca2+) concentration following the arrival of the action potential. Otherwise, presynaptic depression processes, as well as the facilitation ones, depend on neurotransmitter release probability. Thus, synapses with high release probability show few facilitation and are easily depressed because of their ability to deplete faster all synaptic vesicles of the ready releasable pool.

CONCLUSIONS

Short term synaptic plasticity appears to serve as a flexible mechanism for temporal information processing in higher cortical integration.