Effects of electroacupuncture versus manual acupuncture on the human brain as measured by fMRI

Abstract

The goal of this functional magnetic resonance imaging (fMRI) study was to compare the central effects of electroacupuncture at different frequencies with traditional Chinese manual acupuncture. Although not as time-tested as manual acupuncture, electroacupuncture does have the advantage of setting stimulation frequency and intensity objectively and quantifiably. Manual acupuncture, electroacupuncture at 2 Hz and 100 Hz, and tactile control stimulation were carried out at acupoint ST-36. Overall, electroacupuncture (particularly at low frequency) produced more widespread fMRI signal increase than manual acupuncture did, and all acupuncture stimulations produced more widespread responses than did our placebo-like tactile control stimulation. Acupuncture produced hemodynamic signal increase in the anterior insula, and decrease in limbic and paralimbic structures including the amygdala, anterior hippocampus, and the cortices of the subgenual and retrosplenial cingulate, ventromedial prefrontal cortex, frontal, and temporal poles, results not seen for tactile control stimulation. Only electroacupuncture produced significant signal increase in the anterior middle cingulate cortex, whereas 2-Hz electroacupuncture produced signal increase in the pontine raphe area. All forms of stimulation (acupuncture and control) produced signal increase in SII. These findings support a hypothesis that the limbic system is central to acupuncture effect regardless of specific acupuncture modality, although some differences do exist in the underlying neurobiologic mechanisms for these modalities, and may aid in optimizing their future usage in clinical applications.

Copyright 2004 Wiley-Liss, Inc.

Figures

Figure 1

Experimental paradigm and location of acupoint ST‐36 (Zusanli) over the tibialis anterior muscle. Total scan time for each run was 7 min. After needle(s) was inserted into the acupoint, scanning commenced with a rest period of 2 min (R1), followed by two epochs of needle stimulation (S1, S2), each lasting 1 min, separated by a rest interval of 2 min (R2). The run ended with a 1‐min rest interval (R3)..

Figure 2

Somatosensory cortex response to experimental stimulation. Statistical parametric maps for group analysis of MA, EA, and sensory control are displayed over the group averaged anatomic MRI brain scan. Coronal slices are presented with their Talairach space location. Clusters with statistically significant response were smoothed, and color‐coded based on P value (see color bar). Time courses from the boxed region are displayed to the right of each image, demonstrating hemodynamic response. All stimulations produced activation of the contralateral and ipsilateral secondary somatosensory cortex (SII), whereas only high‐ and low‐frequency EA produced activation of the leg homuncular region in the contralateral primary somatosensory cortex (SI).

Figure 3

Limbic system response to experimental stimulation. The results of group analysis for MA, EA, and tactile sensory control are presented. Activated or deactivated regions are color‐coded based on P value. Time courses from the boxed region are displayed to the right of each image. All acupuncture stimulation modalities produced signal decrease in the amygdala and the anterior hippocampus, a result not seen with sensory control stimulation. The contralateral anteriomiddle cingulate (BA 24, 32) demonstrated positive signal response for EA but not for MA or sensory control.

Figure 4

Response of limbic related structures to experimental stimulation. The results of group analysis for MA, EA, and sensory control were color‐coded based on P value and presented as activated or deactivated regions. Although all acupuncture stimulations produced signal decrease in the ventromedial prefrontal cortex and signal increase in the anterior insula, only 2‐Hz EA produced signal increase in the nucleus raphe pontis. Tactile sensory control stimulation did not produce significant response in these regions.