Prolonged Repeated Acupuncture Stimulation Induces Habituation Effects in Pain-Related Brain Areas: An fMRI Study
et al. (2014) Prolonged Repeated Acupuncture Stimulation Induces Habituation Effects in Pain-Related Brain Areas: An
fMRI Study. PLoS ONE 9(5): e97502. doi:10.1371/journal.pone.0097502
Prolonged Repeated Acupuncture Stimulation Induces Habituation Effects in Pain-Related Brain Areas: An fMRI Study
Chuanfu Li 0
Jun Yang 0
Kyungmo Park 0
Hongli Wu 0
Sheng Hu 0
Wei Zhang 0
Junjie Bu 0
Chunsheng Xu 0
Bensheng Qiu 0
Xiaochu Zhang 0
Jie Tian, Institute of Automation, Chinese Academy of Sciences, China
0 1 Laboratory of Digital Medical Imaging, Medical Imaging Center, First Affiliated Hospital, Anhui University of Chinese Medicine , Hefei, Anhui , China , 2 Department of Acupuncture and Moxibustion, First Affiliated Hospital of Anhui University of Chinese Medicine , Hefei, Anhui , China , 3 Department of Biomedical Engineering, Kyung Hee University , Yongin , Republic of Korea, 4 College of Medical Information engineering, Anhui University of Chinese Medicine , Hefei, Anhui , China , 5 School of Information Science and Technology, University of Science and Technology of China , Hefei, Anhui , China , 6 CAS Key Laboratory of Brain Function & Disease and School of Life Sciences, University of Science and Technology of China , Hefei, Anhui , China
Most previous studies of brain responses to acupuncture were designed to investigate the acupuncture instant effect while the cumulative effect that should be more important in clinical practice has seldom been discussed. In this study, the neural basis of the acupuncture cumulative effect was analyzed. For this experiment, forty healthy volunteers were recruited, in which more than 40 minutes of repeated acupuncture stimulation was implemented at acupoint Zhusanli (ST36). Three runs of acupuncture fMRI datasets were acquired, with each run consisting of two blocks of acupuncture stimulation. Besides general linear model (GLM) analysis, the cumulative effects of acupuncture were analyzed with analysis of covariance (ANCOVA) to find the association between the brain response and the cumulative duration of acupuncture stimulation in each stimulation block. The experimental results showed that the brain response in the initial stage was the strongest although the brain response to acupuncture was time-variant. In particular, the brain areas that were activated in the first block and the brain areas that demonstrated cumulative effects in the course of repeated acupuncture stimulation overlapped in the pain-related areas, including the bilateral middle cingulate cortex, the bilateral paracentral lobule, the SII, and the right thalamus. Furthermore, the cumulative effects demonstrated bimodal characteristics, i.e. the brain response was positive at the beginning, and became negative at the end. It was suggested that the cumulative effect of repeated acupuncture stimulation was consistent with the characteristic of habituation effects. This finding may explain the neurophysiologic mechanism underlying acupuncture analgesia.
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Funding: This study was supported by grants from Anhui Provincial Natural Science Foundation under Grant No. 1208085MH147 (http://220.178.98.52/zrkxjj/),
Major Scientific Projects of Anhui Provincial Education Commission under Grant No. KJ2011ZD05 (http://www.ahsr.edu.cn/srmis/), the National Natural Science
Foundation of China under Grant No. 81202768, 31171083, 31230032 (http://www.nsfc.gov.cn/Portal0/default152.htm), and the National Key Basic Research and
Development Program (973) under Grant No. 2010CB530500 (http://www.973.gov.cn/Default_3.aspx). The funders had no role in study design, data collection
and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Acupuncture, an ancient healing technique that originated in
China, is used by millions of patients in many countries [1].
Continuous use of acupuncture in East Asia and more recently
throughout the world has led to the assumption that acupuncture
is a relatively effective and safe procedure. However, with the call
for evidence based medicine, acupuncture has been tested at the
forges of modern medicine [2]. Understanding the physiologic
basis of acupuncture is critical to producing reliable results.
Proposing and testing ideas about the underlying mechanisms of
acupuncture could eventually lead to a real understanding about
how acupuncture does work [3]. However, for the present it
remains to be seen whether we are dealing with a specific
physiological response of the brain to acupuncture, or with
nonspecific reactions to an undifferentiated stimulus [1]. In recent 20
years, fMRI studies have been extensively conducted to investigate
the neurophysiologic mechanism of acupuncture. Although it is
generally agreed that the brain and nervous system play a leading
role in processing acupuncture stimuli [4,5], the specific
mechanism underlying the therapeutic effects of acupuncture is still
under debat (...truncated)