Electronic Modeling of Slow-Waves and Spike-Activity in Intestinal Tissue

Electrical activity in the mammalian gastrointestinal tract includes a basic electrical rhythm, called "slow-waves," plus superimposed pulses referred to as "spike-activity." A currently accepted model for the slow-wave activity compises a set of interconnected oscillators, usually based on van der Pol dynamics. In this paper, an electronics implementation is described which is based on a simplification of the Hodgkin-Huxley equations using the concepts of membrane capacitance and ionic conductances. It is shown that a single oscillator is capable of two modes of oscillation equivalent to slow-waves and spike-activity, and that both modes can occur simultaneously. An explanation of the circuit behavior under each mode is given, and pulse excitation is also considered. The effect of coupling two and four such oscillators together is demonstrated. Thus, a model is presented which is capable of reproducing the major components in gastrointestinal electrical activity, and which is described in physiologically meaningful ionic terms.