On the propagation of a low frequency excitation in a perturbed FitzHugh-Nagumo system: Simulation and experiments

In this paper, we first report the response of an elementary FitzHugh-Nagumo electronic circuit excited by a low frequency sine wave and perturbed by an additive high frequency deterministic perturbation. This preliminary study constitutes a reference to analyze the collective behavior of a chain of 45 coupled elementary cells. In particular, we focus on the propagation of a low frequency sine wave which is only applied on the first fifteen cells of the lattice. It is shown that a high frequency sine wave which perturbs the whole network can enable or disable the propagation of this low frequency signal. By reducing the strength of the intercellular coupling below a critical value, we also establish that the propagation fails whatever the amplitude of the perturbation. Finally, by adding a stochastic perturbation to the high frequency deterministic perturbation, we numerically and experimentally investigate their combined effects on the propagation of the low frequency component. Numerical and experimental results reveal that, under certain conditions, noise can assist the propagation of the low frequency excitation.