PURPOSE: To investigate the neural specificity of pericardium PC6, with the same meridian acupoint PC7 and a treatment-irrelevant acupoint GB37 as separate controls.

MATERIALS AND METHODS: Functional magnetic resonance imaging (MRI) of the whole brain was performed in 36 healthy subjects receiving acupuncture at three acupoints, respectively: the study acupoint (PC6), and control acupoints (PC7 and GB37). A novel nonrepeated event-related (NRER) design paradigm was applied to separately detect neural activities related to different stages of acupuncture (needling manipulation and post-acupuncture rest epoch). Psychophysical responses (Deqi sensations) were also assessed.

RESULTS: Neuroimaging studies of PC6 presented extensive signal attenuations in the cerebrocerebellar and subcortical areas, whereas acupuncture at GB37 induced widespread signal potentiations. In addition, acupuncture at PC6, in comparison with stimulations at PC7 and GB37, selectively evoked neural responses of the insula, hypothalamus, and flocculonodular lobe of cerebellum (nodulus and uvula).

CONCLUSION: These findings may provide preliminary evidence for specific involvements of the cerebellar-hypothalamus and insula following acupuncture at PC6, which underlies the autonomic regulation of vestibular functions. The predominantly time-prolonged deactivations in these areas may also serve the clinical efficacy of PC6 in producing a sedative or tranquilizing effect in antiemetic treatment. (c) 2009 Wiley-Liss, Inc.