Abstract
This is a basic study on evaluations of gastrointestinal motility and autonomic nervous activity, diagnosis of diseases, and examination of effects of medical treatments using electrogastrography (EGG). Using time series analysis, we analyzed temporal variations in the EGGs of healthy young women during sleep and extracted the characteristics of variations. The subjects were healthy women between 18 and 22 years old. Using portable equipment, electrogastrographies at 4 points an the abdominal surface were recorded with the monopolar lead for five hours from the beginning of the sleep. The EGGs were recorded at a sampling frequency of 1 Hz. We calculated cross-correlation functions for all combinations of electrogastrographies recorded at different measuring points. Moreover, frequency characteristics of each EGG were derived from the power spectra estimated by Auto-Regressive models. Every 10 minutes, we specified a dominant frequency and the integrated powers of the frequency band at around 3-cpm (3-cpm band), because the pacemaker for stomach electric activities is around 3-cpm (0.05 Hz). We obtained low contribution rates for electrogastrographies in all combinations of different measuring points and could show that time series of electrogastrographies were independent of each other. As for the power spectra obtained at the 4 electrodes, the dominant frequencies in the 3-cpm band of the point around the fundus were higher than there obtained at other points. In this paper, “Active ratio” was proposed as an index to evaluate the gastrointestinal motility. Temporal variations of this index showed that gastrointestinal motility was considered to be active during the entire sleeping period. Moreover, the difference in the autonomic nervous activity between the first and second halves of their sleeping periods or the effects of circadian rhythm could be evaluated by the power spectra.
