Coherence Resonance in Noise-Induced Excitable Systems

The noise-induced excitable Fitz Hugh-Nagumo system is investigated both analytically and numerically. Analysis of three indices: Lyapunov exponent, the density distribution of trajectories and power spectrum, indicates that the noise can induce the system to forward quite regular dynamics, including coherence resonance. Some other new phenomena related to the potential limit cycle (a moderate noise intensity can excite a potential oscillation, and maximize the oscillation amplitude) are also found for the first time.