Cerebral responses evoked by electrical stimulation of rectosigmoid in normal subjects

We used electroencephalographic methods to evoke and record cerebral responses to electrical stimulation of the rectosigmoid colon in eight healthy male volunteers, 20-40 years old. The stimulus was applied via a probe equipped with bipolar ring electrodes which were attached by suction to the mucosa. The probe was positioned 20 cm above the anus. Cerebral responses were recorded by EEG electrodes. Evoked potentials (EPs) in response to electrical stimulation consisted of a series of successive peaks and troughs in the EEG with good reproducibility within and between subjects. The shape and latencies of the intestinal EPs were comparable to other types of EPs reported before. It is concluded that reproducible EPs can be recorded from the scalp after electrical stimulation of the rectosigmoid. The similarity in appearance of these EPs to those previously reported suggests that visceral afferents were stimulated. The technique may become a useful tool to study visceral nervous connections to the brain in health and disease.