THE EFFECT OF AUTONOMIC NERVOUS-SYSTEM ACTIVITY ON GASTRIC MYOELECTRICAL ACTIVITY - DOES THE SPECTRAL RESERVE HYPOTHESIS HOLD FOR THE STOMACH

Previous studies have associated changes in gastric myoelectrical acti vity during motion sickness, as indexed using the electrogastrogram (E GG), with changes in autonomic nervous system (ANS) activity. Subjects who did not report nausea in a rotating optokinetic drum were charact erized by normal 3 cycles per minute (cpm) gastric myoelectrical activ ity, strong parasympathetic nervous system (PNS) activity, and low sym pathetic nervous system (SNS) activity. The goals of this study were: (1) to determine whether tasks previously shown to alter ANS activity as indexed by changes in cardiac inter-beat intervals (IBIs) would res ult in systematic changes in gastric myoelectrical activity in accord with the findings from motion sickness studies; and (2) to determine w hether the 'spectral reserve hypothesis' applies to gastric myoelectri cal activity. EGGs and IBIs were collected from 24 healthy subjects du ring resting/baseline, reaction time/shock-avoidance (RT) and cold fac e stress (CF) tasks. Tachyarrhythmia was found to be significantly gre ater during the RT task than during the baseline and CF tasks. It was concluded that: (1) tasks that alter ANS activity do systematically al ter gastric myoelectrical activity; and (2) gastric myoelectrical acti vity does not follow the cardiac model of health being associated with increased spectral complexity. (C) 1998 Elsevier Science B.V. All rig hts reserved.