SYNAPTIC PLASTICITY IN THE HIPPOCAMPAL SLICE - FUNCTIONAL CONSEQUENCES

There are 3 known forms of synaptic plasticity at CNS synapses: long-t erm potentiation (LTP) mediated by NMDA receptor activation, LTP media ted by voltage-dependent calcium channel (VDCC) activation, and long-t erm depression (LTD) mediated by the NMDA receptor. All 3 forms of syn aptic plasticity can be observed in hippocampal CA1 cells, all are ind uced by afferent activation, all involve Ca2+ influx, and all activate Ca2+-dependent mechanisms. We consider the functional consequences of the presence of 3, sometime opposing, forms of synaptic plasticity at the same synapse. We suggest that the 2 forms of LTP have different c onsequences for the synapse. We postulate that the co-existence of pot entiating and depressing capabilities influences the network processin g capabilities of neural networks.