A Unified Model of Calcium Dependent Synaptic Plasticity

2 Synapses in the brain are bidirectionally modifiable, but the routes of induction are diverse. In various experimental paradigms, NMDA receptor-dependent long-term depression (LTD) and long-term potentiation (LTP) have been induced selectively by varying (1) the membrane potential of the postsynaptic neurons during synaptic stimulation of a constant frequency, (2) the rate of synaptic stimulation, and (3) the timing of pre-and postsynaptic action potentials. To date, there is no theory to account for these seemingly different forms of synaptic plasticity. In this paper we present a novel mathematical embodiment of bidirectional synaptic plasticity that is able to explain diverse induction protocols with a fixed set of parameters. The key assumptions and consequences of the model can be tested experimentally; further, it provides the foundation for a unified theory of NMDA receptor-dependent synaptic plasticity.