Wave propagation in a FitzHugh-Nagumo-type model with modified excitability.

We examine a generalized FitzHugh-Nagumo (FHN) type model with modified excitability derived from the diffusive Morris-Lecar equations for neuronal activity. We obtain exact analytic solutions in the form of traveling waves using a piecewise linear approximation for the activator and inhibitor reaction terms. We study the existence and stability of waves and find that the inhibitor species exhibits different types of wave forms (fronts and pulses), while the activator wave maintains the usual kink (front) shape. The nonequilibrium Ising-Bloch bifurcation for the wave speed that occurs in the FHN model, where the control parameter is the ratio of inhibitor to activator time scales, persists when the strength of the inhibitor nonlinearity is taken as the bifurcation parameter.