Lévy noise induced escape in the Morris-Lecar model

Abstract: The phenomenon of an excitable system producing a pulse under external or internal stimulation may be interpreted as a stochastic escape problem. This work addresses this issue by examining the Morris-Lecar neural model driven by symmetric \alpha-stable L\'evy motion. Two deterministic indices: the first escape probability and the mean first exit time, are adopted to analyse the state transition in this stochastic model. We calculate both indices in order to understand the transition from the escape region to the target region, and the area of higher indices in escape region. Additionally, we consider the special case of (Gaussian) Brownian motion to compare with (non-Gaussian) L\'evy motion case. Our main results indicate that higher first escape probability promotes the transition, while the mean first exit time reflects the stability of the rest state with the selected escape region. The higher non-Gaussianity index and relatively small noise intensity are more prone to produce spikes. Moreover, by calculating both deterministic indices as functions of noise intensity ratio and non-Gaussianity index, we find that the effect of ion channel noise is more pronounced on the stochastic Morris-Lecar model than noise in the current. This work provides some mathematical understanding about the impact of non-Gaussian, heavy-tailed, burst-like fluctuations on excitable systems such as the Morris-Lecar system.