A Study of Numerical Analysis and Mathematical Modeling of Electrogastrograms in the Young Subjects

Abstract

The electrical activity of the gastrointestine is measured using an electrogastrograph and presented as an electrogastrogram (EGG). Electrogastrography is a noninvasive procedure to evaluate gastrointestinal motility and autonomic nervous system activity. However, EGG do not have been applied to clinical fields as electrocardiogram and electromyogram because EGGs are often contaminated by electro activity in the myocardia and muscles of diaphragm with respiration; furthermore, we do not understand the relationship between EGG and the gastrointestinal motility. Analytical methods of the EGG do not have been established yet. In this paper, the author compared an EGG measured in the abovementioned experiment with numerical solutions to the mathematical model describing the EGG. It is known that the van der pol equation (VPE) is appropriate for obtaining a mathematical model of the EGG because the waveform of the electric potential in the Cajal cells is similar to the graphs of numerical solutions to the VPE. In our previous study, the mathematical model, a system of stochastic differential equations (SDEs), was improved by adding the VPE to a periodic function and random white noises that were analogous to the intestinal motility and other biosignals, respectively. The numerical solutions were quantitatively evaluated by comparing with the distribution of the EGG, its translation error E_trans estimated by the Wayland algorithm, and E_trans' estimated by the Double-Wayland algorithm which was sensitive to stochastic variations.