A Study of Stochastic Resonance as a Mathematical Model of Electrogastrography during Supine Position.

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Electrogastrography (EGG) is an abdominal surface measurement of the electrical activity of the stomach. It is very important clinically to record and analyze multichannel EGGs, which provide more information on the propagation and co-ordination of gastric contractions. This study measured the gastrointestinal motility with an aim to obtain a mathematical model of EGG and to speculate factors to describe the diseases resulting from constipation and erosive gastritis. The waveform of the electric potential in interstitial cells of Cajal is similar to the graphs of numerical solutions to the van der Pol equation. Hence, we added the van der Pol equation to a periodic function and random white noises, which represented the intestinal motility and other biosignals, respectively. We rewrote the stochastic differential equations (SDEs) into difference equations, and the numerical solutions to the SDEs were obtained by the Runge-Kutta-Gill formula as the numerical calculus, where we set the time step and initial values to be O.05 and (0, 0.5), respectively. Pseudorandom numbers were substituted in the white noise terms. In this study, the pseudorandom numbers were generated by the Mersenne Twister method. These numerical calculations were divided into 12000 time steps. The numerical solutions and EGG were extracted after every 20steps. The EGG was well described by the stochastic resonance in the SDEs.
岐阜医療科学大学の論文