The Influence of Initial Values on Spatial Coherence Resonance in a Neuronal Network

Noise-induced single spatial coherence resonance (CR) and multiple spatial CRs simulated in a network have been reported independently in previous studies. In this paper, the relationship between the single and multiple spatial CRs is established by adjusting the initial values of the network composed of Morris-Lecar (ML) model neurons. The ML model manifests a saddle-node bifurcation on an invariant cycle through which a resting state is changed to a stable limit cycle corresponding to period-1 firing. Under resting state, a stable node, a saddle, and an unstable focus coexist. The membrane potential of the unstable focus is much higher than that of the stable node. When the initial value is closer to the unstable focus, the residence time of membrane potential on a high level is longer; correspondingly, the spatial CRs appear more frequently with respect to noise intensity and the coherence degree becomes stronger. The single spatial CR is induced by noise with high intensity. Multiple spatial CRs are induced by noise with high, middle, and even low noise intensities, respectively. When the initial values are closer to an unstable focus, the residence time of membrane potentials on a higher level is longer, which is important to the generation of multiple CRs, and builds a relationship between single and multiple spatial CRs.