Coherent resonance and phase locking in noise-driven excitable systems

The dynamical responses of an excitable FitzHugh-Nagumo (FHN) system under the drive of an external noise are studied. Noise can induce a sequence of firings. The n : m coherent resonance of the FHN oscillator with an intrinsic natural frequency is shown. This effect is discussed by resorting to the phase dynamics of a spike train and the phase synchronization index gamma(nm).