Multichannel recording of cerebral potentials evoked by esophageal balloon distension in humans

In order to obtain insight in the generator localization of esophageal evoked potentials, cerebral responses were recorded from 32 scalp electrodes in five healthy volunteers (two male; three female; age 20-30 years), using series of 50 balloon inflations with 15 ml of air. Sequential topographical mapping of waveforms was performed in each subject. Biphasic waveforms were recorded. At Fpz, a positive deflection at 300 and a negative deflection at 465 msec (P300 and N465) were recorded and at Pz, N300 and P465. At Cz the first peak (N270) was slightly earlier than 300 msec. Waveforms were left to right symmetrical. At distal electrodes, biphasic waveforms were recorded (P300 and N465). In four subjects, a gradual phase shift occurred in between the waveforms at midline electrode Cz and the left and right mastoids. Brain mapping showed phase reversals between central negativity and surrounding positivity at about 300 msec, and between central positivity and surrounding negativity at 400-500 msec. Our data suggest the presence of more than one generator in the anterior and dorsal part of the insula and/or dorsal periinsular cortex.