RESONANCES IN PERIODICALLY FORCED EXCITABLE SYSTEMS

Responses to single and periodic pulse perturbations are studied in two model excitable systems, a six-variable model of the chlorite-iodide reaction and a four-variable extended Oregonator, using the phase excitation curve (PEC). If the period of stimulation is not too short, the PEC enables one to use data on single-pulse stimulation to predict accurately the response to periodic stimulation. The Oregonator model shows only a one-sided Farey sequence, while the chlorite-iodide model exhibits a full sequence. This qualitative difference results not from differences in the dimensionality of the models but from the sensitive dependence of the resonance behavior on the slope of the PEC after the refractory period.