Effect of repetitive transcranial magnetic stimulation on rectal function and emotion in humans

Background A previous brain imaging study demonstrated activation of the right dorsolateral prefrontal cortex (DLPFC) during visceral nociception, and this activation was associated with anxiety. We hypothesized that functional modulation of the right DLPFC by repetitive transcranial magnetic stimulation (rTMS) can reveal the actual role of right DLPFC in brain-gut interactions in humans. Methods Subjects were 11 healthy males aged 23.5 ± 1.4 (mean ± SE) years. Viscerosensory evoked potential (VEP) with sham (0 mA) or actual (30 mA) electrical stimulation (ES) of the rectum was taken after sham, low frequency rTMS at 0.1 Hz, and high frequency rTMS at 10 Hz to the right DLPFC. Rectal tone was measured with a rectal barostat. Visceral perception and emotion were analyzed using an ordinate scale, rectal barostat, and VEP. Key results Low frequency rTMS significantly reduced anxiety evoked by ES at 30 mA (p>0.05). High frequency rTMS-30 mA ES significantly produced more phasic volume events than sham rTMS-30 mA ES (p>0.05). Conclusions and inferences We successfully modulated the gastrointestinal function of healthy individuals through rTMS to the right DLPFC. Thus, rTMS to the DLPFC appears to modulate the affective, but not direct, component of visceral perception and motility of the rectum.