Role of the colored noise in a FitzHugh-Nagumo system driven by a periodic signal

During these last years the interest in neuronal dynamics increased. The study of this kind of system has been carried out by using the FitzHugh-Nagumo (FHN) model that is a simplified modification of the Hodgkin-Huxley model. Many interesting phenomena can be observed in the presence of fluctuations: modification of detection threshold by manipulation of noisy parameters (FHN model), noise-induced activation and coeherence resonance for suitable noise amplitude (absence of periodic signal), resonant activation for high periodic signals and noise reduction, intrinsic stochastic resonance (ISR) in Hodgkin-Huxley neuron and the enhancement of a weak signal by tuning the subthreshold intrinsic oscillation, Resonant Activation (RA) and Noise Enhanced Stability (NES) in FHN model [5], dependence of neuron firing on subthreshold periodic signal and additive noise and optimization of the interspike time, stochastic resonance maximized in the presence of coloured noise I/f^{beta} for beta = 1. In this work, by using coloured noise sources with correlation time tau, we investigate the effects of fluctuations on the FHN dynamics. In particular we study the mean response time (MRT) as a function both of noise intensity and correlation time.