Molecular Pain 2010, 6:73
doi:10.1186/1744-8069-6-73(Open Access)
1 Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
2 School of Life Science and Technology, Xidian University, Xi'an 710071, China
3 Beijing TCM Hospital affiliated to Capital University of Medical Sciences, Beijing 10010, China
4 West China Hospital of Sichuan University, Sichuan 610041, China
5 Department of Radiology, Beijing Tiantan Hospital, Capital University of Medical Sciences, Beijing, 100050, China
6 McKnight Brain Institute, Departments of Psychiatry and Neuroscience, University of Florida, Gainesville, FL 32610, USA
7 Department of Biomedical Engineering, Peking University, Beijing 100871, China
| Published: | 2 November 2010 |
Abstract
Background
Accumulating neuroimaging studies in humans have shown that acupuncture can modulate a widely distributed brain network, large portions of which are overlapped with the pain-related areas. Recently, a striking feature of acupuncture-induced analgesia is found to be associated with its long-last effect, which has a delayed onset and gradually reaches a peak even after acupuncture needling being terminated. Identifying temporal neural responses in these areas that occur at particular time -- both acute and sustained effects during acupuncture processes -- may therefore shed lights on how such peripheral inputs are conducted and mediated through the CNS. In the present study, we adopted a non-repeated event-related (NRER) fMRI paradigm and control theory based approach namely change-point analysis in order to capture the detailed temporal profile of neural responses induced by acupuncture.
Results
Our findings demonstrated that neural activities at the different stages of acupuncture presented distinct temporal patterns, in which consistently positive neural responses were found during the period of acupuncture needling while much more complex and dynamic activities found during a post-acupuncture period. These brain responses had a significant time-dependent effect which showed different onset time and duration of neural activities. The amygdala and perigenual anterior cingulate cortex (pACC), exhibited increased activities during the needling phase while decreased gradually to reach a peak below the baseline. The periaqueductal gray (PAG) and hypothalamus presented saliently intermittent activations across the whole fMRI session. Apart from the time-dependent responses, relatively persistent activities were also identified in the anterior insula and prefrontal cortices. The overall findings indicate that acupuncture may engage differential temporal neural responses as a function of time in a wide range of brain networks.
Conclusions
Our study has provided evidence supporting a view that acupuncture intervention involves complex modulations of temporal neural response, and its effect can gradually resolve as a function of time. The functional specificity of acupuncture at ST36 may involve multiple levels of differential activities of a wide range of brain networks, which are gradually enhanced even after acupuncture needle being terminated.
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