A generalized Hebbian rule for activity-dependent synaptic modifications

In this paper our previous model of activity-dependent synaptic modificatio n is extended and applied to a model neuron with active dendrites and is us ed in computer simulations to examine in detail the dependence of synaptic modifications on the interval between the onset of excitatory postsynaptic potentials (EPSPs) and postsynaptic action potentials (APs). The EPSP ampli tude is increased when the action potentials occur within 20 ms after EPSPs and is reduced when the action potentials occur within 20 ms before EPSPs. Furthermore, the absolute value of changes in the EPSP amplitude tends to increase as the interval between APs and EPSPs decreases. A learning rule f or synaptic modifications described in this paper may, hence, further gener alize the Hebbian rule which requires conjunctive presynaptic and postsynap tic activity for synaptic modification to occur. Functional roles for such a generalized Hebbian rule are also considered. (C) 2000 Elsevier Science L td. All rights reserved.