Long-term regulation of short-term plasticity: a postsynaptic influence on presynaptic transmitter release.

The dynamics of presynaptic transmitter release are often matched to the physiological properties and function of the postsynaptic cell. Evidence in organisms as diverse as the cricket central nervous system and the cat spinal cord suggests that retrograde signaling is essential for matching presynaptic release properties to the postsynaptic cell. The cricket central nervous system is favorably organized for analysis of synaptic function in the central nervous system. Several lines of independent evidence suggest that it is possible to reliably estimate the size of single quantal release events at the sensory to interneuron synapses of the cricket. A quantal analysis suggests that a retrograde influence on the probability of presynaptic release is responsible for matching presynaptic dynamic properties to postsynaptic targets. This retrograde interaction is hypothesized to be a long-term modification on the basal probability of presynaptic release.