Alteration of gastric myoelectrical and autonomic activities with audio stimulation in healthy humans

Objective. Cold or emotional stress was reported to affect gastric myoelectrical activity. The aim of this study was to investigate the effects of music or noise on gastric myoelectrical activity and autonomic function in healthy volunteers. Material and methods. The study was performed in 10 fasted healthy volunteers and included 30 min at baseline, 30 min of classical music via headphones and 30 min of loud household noises via headphones. The electrogastrogram (EGG) readings were recorded simultaneously with the electrocardiogram (ECG) recording. Results. Both classical music and noise altered the regularity of gastric slow waves. The percentage of normal 2-4 cycles/ min (cpm) waves was reduced from 77.9 ± 4.7% at baseline to 66.9 ± 5.4% during music (p <0.006) and 67.7 ± 5.4% during noise (p <0.05). The reduction was attributed to a significant increase in bradygastria (15.8 ± 3.9% versus 9.8 ± 2.6%, p <0.04) with the music and a significant increase in arrhythmia (7.4 ± 1.6% versus 2.0 ± 1.1%, p <0.02) with the noise. The dominant frequency and power of the EGG were, however, not altered with either music or noise. Neither music nor noise had any effect on the autonomic function assessed by the heart rate variability. Conclusions. Audio stimulation, with both music and noise, alters the rhythmicity of gastric slow waves. Classical music seems to increase bradygastria, whereas, household noise may increase arrhythmia. The effect of audio stimulation on the gastric slow wave does not seem to involve sympathetic or vagal efferent pathways assessed by the spectral analysis of heart rate variability.