Central nervous pathway for acupuncture stimulation: Localization of processing with functional MR imaging of the brain - Preliminary experience

PURPOSE: To characterize the central nervous system (CNS) pathway for acupu ncture stimulation in the human brain by using functional magnetic resonanc e (MR) imaging. MATERIALS AND METHODS: Functional MR imaging of the whole brain was perform ed in two groups of nine healthy subjects during four stimulation paradigms : real acupuncture at acupoints ST.36 (on the leg) and LI.4 (on the hand) a nd control stimulations (minimal acupuncture and superficial pricking on th e leg). Stimulations were performed in semirandomized, balanced order neste d within two experiments. Psychophysical responses (pain, De-Qi effect [cha racteristic acupuncture effect of needle-manipulation sensation], anxiety, and unpleasantness) and autonomic responses were assessed. Talairach coordi nates-transformed imaging data were average for a group analysis. RESULTS: Acupuncture at LI.4 and ST.36 resulted in significantly higher sco res for De-Qi and in substantial bradycardia. Acupuncture at both acupoints resulted in activation of the hypothalamus and nucleus accumbens and deact ivation of the rostral part of the anterior cingulate cortex, amygdala form ation, and hippocampal complex; control stimulations did not result in such activations and deactivations. CONCLUSION: Functional MR imaging can demonstrate the CNS pathway for acupu ncture stimulation. Acupuncture at ST36 and LI.4 activates structures of de scending antinociceptive pathway and deactivates multiple limbic areas subs erving pain association. These findings may shed light on the CNS mechanism of acupuncture analgesia and form a basis for future investigations of end ogenous pain modulaiton circuits in the human brain.