Phase locking, period doubling, and chaotic phenomena in externally driven excitable systems

The behavior of excitable systems periodically stimulated by pulses is investigated. The nonself-oscillating regime is studied in the simplest realistic model. The global bifurcation structure is similar in several aspects to the one corresponding to driven oscillators. It includes phase locking, quasiperiodicity, period doubling, and chaos. The unexpected persistence of this structure is explained by analytical arguments and its scaling properties are numerically determined.