Gastric myoelectric activity during low frequency oscillation.

BACKGROUND

The normal 3 cycles per minute (3 c/m) resting activity of the stomach has been reported to shift into the range of 4-9 c/m (tachyarrhythmia) in subjects with symptoms of motion sickness. Previous studies have provoked motion sickness with an optokinetic stimulus and have not normally reported changes relative to a control condition. The present experiment investigated changes in the electrogastrogram (EGG) during a control condition and during exposure to 0.125 Hz off-axis yaw oscillation of the body.

METHODS

There were 16 male subjects who participated in the two conditions 1 wk apart. The electrogastrogram, respiration rate and subjective ratings of sickness were monitored throughout both conditions. Spectral analysis of the EGG time histories provided measures of 3 c/m power and tachyarrhythmia power, which were also expressed as a percentages of EGG power over the total EGG frequency range (0.04 to 0.16 Hz.). The median frequency of the EGG over this bandwidth was also calculated.

RESULTS

During motion exposure, the median frequency of the EGG and the percentage tachyarrhythmia power increased and the percentage 3 c/m power decreased relative to a pre-exposure baseline period and relative to the static control condition.

CONCLUSIONS

Low frequency off-axis yaw oscillations disrupted the normal resting gastric myoelectric activity relative to a control condition.