Local differences in electrogastrograms recorded from 16 locations on the human thoraco-abdominal surface.

Local differences in the electrogastrographic (EGG) indices were studied. The indices include the spectral frequency, the instability factor (IF) of the spectral frequency, and the power content in addition to the usual power amplitude of 5 frequency groups as follows: the 1-cpm group (0-2.4), the 3-cpm group (2.5-4.9), the 6-cpm group (5.0-7.4), the 8-cpm group (7.5-9.9), and the 10-cpm group (10.0-12.9). In general, the infraumbilical frequency and the IF of both of the 3- and 6-cpm groups were higher than those of the epigastric frequencies. In contrast, both the epigastric power amplitude and the power content of the 3- and 6-cpm groups were higher than those of the infraumbilical ones. Mapping of the absolute power amplitude and superimposing the maximal power foci further visualized and clarified the local differences in the epigastric and infraumbilical myoelectrical activity, especially of gastric and colonic activity.