Investigation of Acupuncture-specific BOLD Signal Changes Using Multiband Acquisition and Deconvolution Analysis

PURPOSE: We investigated the temporal dynamics of blood oxygen level-dependent (BOLD) signal responses during various stimuli, including real acupuncture, sham acupuncture, and palm scrubbing. For this purpose, deconvolution analysis was used to perform measurements using multi-band (MB) echo-planar imaging (EPI), which can improve time resolution, and to analyze brain responses without an expected reference function. METHODS: We devided 26 healthy right-handed adults into a group of 13 who received real acupuncture stimulation with manual manipulation and the other group of 13 who received sham acupuncture and palm scrubbing tactical stimulations. Data analysis was performed with a combination of analysis packages. RESULTS: We found stimulus-specific impulse responses of the BOLD signal in various brain regions. During real acupuncture, activated areas were observed in the secondary somatosensory cortex (SII) and insula during stimulation and in the anterior cingulate cortex (ACC), supplementary motor area (SMA), and thalamus after the stimulation. During sham acupuncture, activated areas were observed in the SII, insula, and thalamus during simulation. During the scrubbing condition, activated areas were observed in the contralateral primary somatosensory cortex (SI), SII, insula, and thalamus during stimulation. In particular, during the real acupuncture condition, significantly delayed and long-sustained increased signals were observed in several brain regions, in contrast to the signals induced with sham acupuncture and palm scrubbing. COCLUSION: We speculated that the delayed and long-sustained signal increases were caused by peripheral nociceptors, flare responses, and time-consuming processing in the central nervous system. We used deconvolution analysis with MB EPI and tent functions to identify the delayed increase in the BOLD signal in the area related to pain perception specifically observed in real acupuncture stimulation. We propose that the specific BOLD signal change observed in this study will lead to the elucidation of the mechanism underlying the therapeutic effect of acupuncture stimulation.