Competitive Hebbian learning through spike-timing-dependent synaptic plasticity

Hebbian models of development and learning require both activity-dependent synaptic plasticity and a mechanism that induces competition between differ ent synapses. One form of experimentally observed long-term synaptic plasti city, which we call spike-timing-dependent plasticity (STDP), depends on th e relative timing of pre- and postsynaptic action potentials. In modeling s tudies, we find that this form of synaptic modification can automatically b alance synaptic strengths to make postsynaptic firing irregular but more se nsitive to presynaptic spike timing. It has been argued that neurons in viv o operate in such a balanced regime. Synapses modifiable by STDP compete fo r control of the timing of postsynaptic action potentials. Inputs that fire the postsynaptic neuron with short latency or that act in correlated group s are able to compete most successfully and develop strong synapses, while synapses of longer-latency or less-effective inputs are weakened.