A pilot study of functional magnetic resonance imaging of the brain during manual and electroacupuncture stimulation of acupuncture point (LI-4 Hegu) in normal subjects reveals differential brain activation between methods

OBJECTIVES: To characterize the brain activation patterns evoked by manual and electroacupuncture on normal human subjects.
DESIGN: We used functional magnetic resonance imaging (fMRI) to investigate the brain regions involved in electroacupuncture and manual acupuncture needle stimulation. A block design was adopted for the study. Each functional run consists of 5 minutes, starting with 1-minute baseline and two 1-minute stimulation, the interval between the two stimuli was 1 minute. Four functional runs were performed on each subject, two runs for electroacupuncture and two runs for manual acupuncture. The order of the two modalities was randomized among subjects. During the experiment, acupuncture needle manipulation was performed at Large Intestine 4 (LI4, Hegu) on the left hand. For each subject, before scanning started, the needle was inserted perpendicular to the skin surface to a depth of approximately 1.0 cm. Electroacupuncture stimulation was delivered using a continuous rectangular wave form (pulse width 30 ms) at a frequency of 3 Hz. For manual acupuncture, the needle was rotated manually clockwise and counterclockwise at a rate of about 180 times per minute (3 Hz).
SUBJECTS: Eleven right-handed, normal, healthy volunteer adults, 6 male and 5 female, ages 21-64 participated in the experiment.
RESULTS: Results showed that electroacupuncture mainly produced fMRI signal increases in precentral gyrus, postcentral gyrus/inferior parietal lobule, and putamen/insula; in contrast, manual needle manipulation produced prominent decreases of fMRI signals in posterior cingulate, superior temporal gyrus, putamen/insula.
CONCLUSION: These results indicate that different brain networks are involved during manual and electroacupuncture stimulation. It suggests that different brain mechanisms may be recruited during manual and electroacupuncture.