Composite synthesized relaxation oscillators: Application to modeling of colonic electrical control and response activity

A composite synthesized relaxation oscillator (SRO), whose output exhibits two types of interrelated rhythmic activities, is proposed. A slow rhythmic activity is present at all times, and it controls the appearance of a faster bursting activity that is not always present. The second-order SRO dynamics for producing omnipresent and labile thythmic activities are generalized as fourth-order composite SRO dynamics for producing a composite rhythmic activity. To illustrate the relevance of this composite SRO to gastrointestinal electrical activities, a population of coupled SROs which has been previously used to model colonic electrical control activity, is generalized to represent a population of coupled composite SROs to model both electrical control and response activities in the colon.