Synaptic plasticity, conduction delays, and inter-areal phase relations of spike activity in a model of reciprocally connected areas

Abstract

Multi-electrode recordings revealed that fast oscillatory (30– 60 Hz ) spike activity is often synchronized with zero phase lag, even for recording sites in distant cortical areas. We show in this simulation study that the dominance of zero-phase correlations is inconsistent with the long conduction delays measured between distant areas: For realistic delays, reciprocally connected neuron populations exhibit anti-phase rather than zero-phase correlations. We show that this inconsistency can be removed by taking into account spike-timing-dependent synaptic plasticity (STDP), as found in experiments (Science 275 (1997) 213). We demonstrate that STDP can weaken fast excitatory feedback and strengthen slower feedback with delays in the range of one oscillation period. This yields stable zero-lag oscillations, even for realistic delays.