Bifurcation and chaos observed in coupled BVP neurons with external impulsive forces

We investigate bifurcation and chaos observed in coupled Bonhoffer van der Pol (BVP) neurons with external impulsive forces. Although the single neuron without the external force has only one equilibrium point, combining these n (n⩾3) neurons unidirectionally in a ring, n-phase periodic solutions are generated. Applying the impulsive forces, successive period-doubling bifurcations of the n-phase solution occur and chaotic states, namely n-phase chaos, appear. When n=2 and 3, we find the parameter regions in which the switching phenomena of burst firing are observed. Moreover, the mechanisms of the switching phenomena are clarified by numerical bifurcation analysis