A Phenomenological Calcium-Based Model of STDP

Activity-dependent synaptic plasticity is believed to underlie functional reconfiguration of neuronal circuits, which in turn serves as the biological substrate of higher brain functions such as learning and memory (Hebb 1949; Milner et al. 1998; Abbott and Nelson 2000). Decades after Donald Hebb’s famous neurophysiological postulate (Hebb 1949), various forms of synaptic plasticity including long-term potentiation (LTP) and long-term depression (LTD) have been the subject of intense experimental study (Bliss and Collingridge 1993; Malenka and Nicoll 1999; Lisman et al. 2003; Derkach et al. 2007). Among them, the recently discovered spike timingdependent plasticity (STDP) – during which the direction and extent of synaptic modification depend critically on the relative timing of pre- and postsynaptic action potentials or spikes (Bell et al. 1997; Magee and Johnston 1997; Markram et al. 1997; Mehta et al. 1997; Bi and Poo 1998; Debanne et al. 1998; Zhang et al. 1998; Feldman 2000) – has gained popularity partly because it is regarded as a physiologically relevant form of Hebbian plasticity (Abbott and Nelson 2000; Bi and Poo 2001; Dan and Poo 2006).