title: Bifurcation analysis of solitary and synchronized pulses and formation of reentrant waves in laterally coupled excitable fibers.
abstract: We study the dynamics of a reaction-diffusion system comprising two mutually coupled excitable fibers. We consider a case in which the dynamical properties of the two fibers are nonidentical due to the parameter mismatch between them. By using the spatially one-dimensional FitzHugh-Nagumo equations as a model of a single excitable fiber, synchronized pulses are found to be stable in some parameter regime. Furthermore, there exists a critical coupling strength beyond which the synchronized pulses are stable for any amount of parameter mismatch. We show the bifurcation structures of the synchronized and solitary pulses and identify a codimension-2 cusp singularity as the source of the destabilization of synchronized pulses. When stable solitary pulses in both fibers disappear via a saddle-node bifurcation on increasing the coupling strength, a reentrant wave is formed. The parameter region, where a stable reentrant wave is observed in direct numerical simulation, is consistent with that obtained by bifurcation analysis.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan. yanagita@nsc.es.hokudai.ac.jp
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yanagita
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Suetani
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Aihara