The temporal-spatial encoding of acupuncture effects in the brain.

BACKGROUND: Functional specificities of acupuncture are crucial to its clinical efficacy such as in pain management. Whether acupuncture needling at a peripheral acupoint produces a distinct pattern of brain response that has both functional specificity and therapeutic relevance remains controversial.

RESULTS: This fMRI study employed a complex network analysis approach to test the hypothesis that acupuncture stimulation at an acupoint would induce correspondingly activity changes in one or more intrinsic or resting-state brain networks. Built upon the sustained effect of acupuncture and its time-varying characteristics, we constructed a dynamic encoding system with a hub at the posterior cingulate cortex and precuneus (PCC/pC). We found that needling at two visual acupoints (GB37 and BL60) and a non-visual acupoint (KI8) induced a converging brain response spatially overlapped at the PCC/pC. We also found distinct neural modulations during and after the acupoint stimulation, in which the PCC/pC was interacting with a visual resting-state network in different patterns. Furthermore, there was a delayed functional correspondence between the intrinsic visual network and manipulating the visual acupoint (i.e., GB37 or BL60 but not the non-visual acupoint KI8) via the PCC/pC, implicating a specific temporal-spatial encoding/decoding mechanism underlying the post-effect of acupuncture.

CONCLUSIONS: This study provided an integrated view to explore the functional specificity of acupuncture, in which both needling sensation and the following neural cascades may contribute to the overall effect of acupuncture through dynamic reconfiguration of complex neural networks.

PMID: 21429192