Baseline Evaluation And Application Of Block Paradigm In The Acupuncture Mechanism-Related Researches

With the globally increasing medical expenditure, acupuncture by its remarkable economic and little side-effect has been promoted and popularized and gradually recognized by the international medical community. Due to the rapid development of modern medical imaging, particularly the functional magnetic resonance imaging (fMRI), the exploration of the relations among acupoints, brain and viscera has become possible. However, the present fMRI acupuncture investigation is still in its early stage, its research method has yet to be further improved.The existing model-based experimental paradigms and analysis methods choose the post-acupuncture resting as part of the baseline; But the Traditional Chinese Medicine and clinical evidence indicate that acupuncture effect takes on character of sustaining, thus the model-based multi-block paradigm is no longer suitable for studies of acupuncture mechanism. Here, we proposed that only the pre-acupuncture resting is optimal to be used as baseline. Due to the needle insertion the resting before acupuncture has two different states, so which rest state as the only baseline is essential? Previous research considered that the pre- and post-acupuncture resting state was consistent, exclusive of consider the sustaining effect; therefore it is of great demand to evaluate the reliability of this conclusion.In this paper, we applied a new data analysis approach, multi-block general linear model, in two different kinds of experiments considering the acupuncture sustaining effect. These two experiments were both used multi-block paradigm, but assigned pre-acupuncture resting and post-acupuncture resting as their baselines respectively. We compared the neutral responses derived from these two experiments and demonstrated that the needle insertion could bring significant change to the neutral responses of brain cortex. This result is contrary to the opinion of previous researchers that the pre-acupuncture and post-acupuncture resting periods are consistent. Furthermore, the results corroborated the existence of acupuncture's prolonged effects. Then, we introduced the non-repeated event-related experimental design to preliminarily study the mechanism of action of acupuncture analgesia. The finding indicated that acupuncture at acupoint and sham-acupoint can have different modulation patterns to the brain neural networks during resting epoch, through comparing the brain neural networks during the resting state after acupuncture at acupoint ST36 (Zusanli) and sham-acupoint. This different modulation patterns supported the view that acupuncture has the specificity. Moreover, the results of acupuncture stimulation at ST36 demonstrated that acupuncture analgesia worked with distinctive parts of the anterior cingulate cortex in different approaches, these findings shed light on the understanding of acupuncture analgesia mechanism.