Acupuncture modulates the limbic system and subcortical gray structures ofthe human brain: Evidence from fMRI studies in normal subjects

Acupuncture, an ancient therapeutic technique, is emerging as an important modality of complementary medicine in the United States. The use and effica cy of acupuncture treatment are not yet widely accepted in Western scientif ic and medical communities. Demonstration of regionally specific, quantifia ble acupuncture effects on relevant structures of the human brain would fac ilitate acceptance and integration of this therapeutic modality into the pr actice of modem medicine. Research with animal models of acupuncture indica tes that many of the beneficial effects may be mediated at the subcortical level in the brain. We used functional magnetic resonance imaging (fMRI) to investigate the effects of acupuncture in normal subjects and to provide a foundation for future studies on mechanisms of acupuncture action in thera peutic interventions. Acupuncture needle manipulation was performed at Larg e Intestine 4 (LI 4, Hegu) on the hand in 13 subjects [Stux, 1997]. Needle manipulation on either hand produced prominent decreases of fMRI signals in the nucleus accumbens, amygdala, hippocampus, parahippocampus, hypothalamu s, ventral tegmental area, anterior cingulate gyrus (BA 24), caudate, putam en, temporal pole, and insula in all 11 subjects who experienced acupunctur e sensation. In marked contrast, signal increases were observed primarily i n the somatosensory cortex. The two subjects who experienced pain instead o f acupuncture sensation exhibited signal increases instead of decreases in the anterior cingulate gyrus (BA 24), caudate, putamen, anterior thalamus, and posterior insula. Superficial tactile stimulation to the same area elic ited signal increases in the somatosensory cortex as expected, but no signa l decreases in the deep structures. These preliminary results suggest that acupuncture needle manipulation modulates the activity of the limbic system and subcortical structures. We hypothesize that modulation of subcortical structures may be an important mechanism by which acupuncture exerts its co mplex multisystem effects. (C) 2000 Wiley-Liss, Inc.