Somatosensory-evoked potentials and cortical activities evoked by magnetic stimulation on acupoint in human.

Two acupuncture manipulations are clinically used: manual manipulation and electrical acupuncture. There is little published on the EEG changes during magnetic stimulation on an acupuncture site. In this study, EEG data in response to magnetic stimulation on HeGu (LI 4) acupoint were measured to determine whether magnetic acupoint stimulation might modulate ongoing EEG or not. Eighteen healthy volunteers (13 male, 5 female) 20 to 35 years old were chosen in this experiment, with consent obtained before the study. The highest evoked potential was recorded in FCZ electrode, at about 140-170 ms (P150) after acupoint stimulation, but not mock point stimulation. Comparison of the somatosensory-evoked potentials in response to acupoint stimulation and mock point stimulation showed that P150 was specific to acupoint stimulation. With regard to the location of P150 in the human brain, we suggest that magnetic stimulation on HeGu acupoint would affect specific brain areas compared with the mock point. The difference in the anatomical structure of acupoint and non-acupoint may explain the specific acupoint-brain correlation, and P150 may be a characteristic activation in response to acupoint afferent.