title: Noise-enhanced excitability in bistable activator-inhibitor media.
abstract: We show that external fluctuations induce excitable behavior in a bistable spatially extended system with activator-inhibitor dynamics of the FitzHugh-Nagumo type. This can be understood as a mechanism for sustained signal propagation in bistable media. The phase diagram of the stochastic system is analytically obtained and numerically verified. For small-noise intensities, front propagation becomes unstable, and excitable pulses arise as the only possible spatiotemporal behavior of the system. For large-noise intensities, on the other hand, the system enters an effective regime of oscillatory behavior, where it exhibits spontaneous nucleation of pulses and synchronized firing.
authors.affiliation: Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain. jordi.g.ojalvo@upc.es
authors.forename: J
authors.initials: J
authors.lastname: García-Ojalvo
authors.forename: F
authors.initials: F
authors.lastname: Sagués
authors.forename: J M
authors.initials: JM
authors.lastname: Sancho
authors.forename: L
authors.initials: L
authors.lastname: Schimansky-Geier