Noise-driven transition to quasi-deterministic limit cycle dynamics in excitable systems

The effect of small-amplitude noise on excitable systems with large time-scale separation is analyzed. It is found that small random perturbations of the fast excitatory variable result in the onset of a quasi-deterministic limit cycle behavior, absent without noise. The limit cycle is established at a critical value of the amplitude of the noise, and its period is nontrivially determined by the relationship between the noise amplitude and the time scale ratio. It is argued that this effect might provide a mechanism by which the function of biological systems operating in noisy environments can be robustly controlled by the level of the noise.