Excitable structures in stochastic bistable media

We examine the influence of parametric noise on the spatiotemporal behavior of a bistable medium with activator-inhibitor dynamics. Deterministic fron t propagation in one dimension is seen to be destabilized by the external n oise, resulting in the propagation of solitary pulses through the system. F or large enough noise levels, this state becomes unstable via a backfiring mechanism, which eventually leads to a turbulent stale.