Long-term modification of synaptic efficacy can depend on the timing of pre
- and postsynaptic action potentials. In model studies, such spike timing-d
ependent plasticity (STDP) introduces the desirable features of competition
among synapses and regulation of postsynaptic firing characteristics. STDP
strengthens synapses that receive correlated input, which can lead to the
formation of stimulus-selective columns and the development, refinement, an
d maintenance of selectivity maps in network models. The temporal asymmetry
of STDP suppresses strong destabilizing self-excitatory loops and allows a
group of neurons that become selective early in development to direct othe
r neurons to become similarly selective. STDP, acting alone without further
hypothetical global constraints or additional forms of plasticity, can als
o reproduce the remapping seen in adult cortex following afferent lesions.