The structural and molecular mechanism of neuronal presynaptic plasticity

Synaptic plasticity is a physiologically important mechanism underlying neuronal information processing. In terms of expression site, synaptic plasticity can be divided into presynaptic and postsynaptic. Presynaptic plasticity is implicated in the modulation of the neurotransmitter release machinery and consequently in synaptic strength. From a physiological perspective, this type of plasticity could be derived from a change in quantal size, active zone structure, probability of transmitter release, especially, synaptic vesicle dynamics: from synaptic vesicle trafficking to the nerve terminal, docking at or fusion with the presynaptic plasma membrane, and finally, reconstitution following endocytosis. Each of these steps is mediated by the concerted activities of multiple proteins and protein complexes, thus presenting numerous points at which the cascades leading to effective neurotransmitter release could be modulated. Potential mechanisms by which the synaptic vesicle release could be modulated and synaptic activity could be silenced or enhanced at the presynaptic terminal are reviewed.