Local differences in electrogastrographic responses to the stress of the mirror drawing test (MDT) as determined by multichannel electrogastrography.

Electrogastrograms (EGGs) were recorded in human subjects (n=58) at 16 locations on the thoraco-abdominal surface before (at rest) and during the stress of the mirror drawing test (MDT) and after having a test meal. The power amplitude ratios and power content ratios of MDT to rest (MDT/rest) and postprandial state to rest (PPR/rest) were compared between gastric channels 5 and 8, and the infraumbilical channels 12, 13, 14, 15, and 16. Generally, the ratio of the 3-cpm group in channels 5 and 8 was lower than that of the infraumbilical channels 12-16 during MDT. In contrast, the ratios were higher in the epigastric channels than in the infraumbilical channels after a test meal. Significant differences between the epigstric and infraumbilical channels were found in the comparisons of the power content ratios. The infraumbilical channels were facilitated and the epigastric channels inhibited during MDT. After eating a meal, in contrast, the postprandial epigastric 3-cpm EGGs were facilitated. The epigastric 3-cpm EGG activity reflects gastric myoelectric activity, while the infraumbilical 3-cpm activity reflects that of the colon. Therefore, it is suggested that the acute stress of the MDT generally inhibited the gastric EGG and facilitated the colonic EGG, indicating gastric inhibition and colonic facilitation. The topographic EGG maps of the power content ratios and the absolute power ratios visually confirmed these findings.