Effect of Spike-Timing-Dependent Plasticity on Stochastic Spike Synchronization in an Excitatory Neuronal Population

We consider an excitatory population composed of subthreshold neurons which exhibit noise-induced spikings. This neuronal population has adaptive dynamic synaptic strengths governed by the spike-timing-dependent plasticity (STDP). In the absence of STDP, stochastic spike synchronization (SSS) between noise-induced spikings of subthreshold neurons was previously found to occur over a large range of intermediate noise intensities. Here, we investigate the effect of STDP on the SSS by varying the noise intensity. A "Matthew" effect in synaptic plasticity is found to occur due to a positive feedback process. Good synchronization gets better via long-term potentiation (LTP) of synaptic strengths, while bad synchronization gets worse via long-term depression (LTD). Emergence of LTP and LTD of synaptic strengths is investigated through microscopic studies based on both the distributions of time delays between the pre- and the postsynaptic spike times and the pair correlations between the pre- and the postsynaptic IISRs (instantaneous individual spike rates).