Interplay between internal delays and coherent oscillations in delayed coupled noisy excitable systems

Abstract

Numerical study of variations in coherence of spike trains produced by two stochastically perturbed FitzHugh-Nagumo excitable systems with internal and coupling time-delays is performed. Both, the internal time-delay and the interaction time-delay in some domains of values can substantially increase the coherence but the interplay of the two delays can also lead to quite incoherent spike trains. Numerically observed dependence of the coherence on the delays is qualitatively explained by considering the bifurcations in the system caused by the variations of the values of the internal and the interaction time-lags.