Effects of esophageal stimulation in healthy subjects

We studied the effects of esophageal electrical stimulation on heart rate v ariability power spectra (PS/HRV) and cortical evoked potentials (EPs) in h ealthy subjects. The intensity of stimulation was varied from 2.7 to 20 mA. We found that the amplitude of the cortical evoked potentials (amplitude o f the N-2/P-2 peak) increased from 5.1 +/- 0.7 mu V at 5 mA to 16.3 +/- 1.1 mu V at 20 mA. The PS/HRV showed an increase in the vagal modulation of th e sinus node. When the stimulation frequency was varied from 0.1 to 1 Hz at a constant intensity of 15 mA, the amplitude of cortical EPs (N-2/P-2, pea k) decreased with increase in the frequency of stimulation (p < 0.05). The LF:HF ratio decreased significantly for all frequencies of stimulation (p < 0.005). An experimental paradigm to evoke the cognitive component in the c ortical EPs yielded a peak around 354 ms following the stimulus.