The Neurological Effects of PC-6

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PC-6 (Pericardium-6) is an acupuncture point empirically known to treat nausea and vomiting, especially as a side-effect of pregnancy, chemotherapy and radiotherapy. The Pericardium is connected to the chest, diaphragm and upper abdomen. This explains PC-6’s function for relieving nausea and vomiting, at least through TCM theory.

So how can PC-6 be explained physiologically outside of TCM theory?

Dr. Lijun Bai published a study in 2010 entitled “Neural Specificity of Acupuncture Stimulation at Pericardium 6: Evidence from an FMRI Study.” His team performed functional magnetic resonance imaging (fMRI) on the brain of 36 healthy subjects at three acupuncture points: PC-6, PC-7 (same channel and median innervation), and GB-37 (different channel, anti-emetic).

The results drew the following conclusions:

PC-6 stimulates areas of the brain involved in vestibular function, visceral sensation of the gastrointestinal tract, and the “fight-or-flight” response. This may explain its function on relieving nausea and vomiting.

    • FMRIs show that stimulation of PC-6 evokes negative hemodynamic responses in the areas of the brain involved in vestibular function and visceral sensations of the gastrointestinal tract. Those areas include the insular cortex, and the nodulus and uvula of the hypothalamus. This may explain how PC-6 relieves nausea and vomiting. Studies show the insular cortex plays a role in the visceral sensations of the throat, esophagus, and other areas of the gastrointestinal tract. The nodulus and uvula are involved in vestibular function.
  • PC-6 evoked negative hemodynamic responses in the limbic / paralimbic-cerebellum and subcortical areas of the brain. These areas engage in motivation and the autonomic nervous system, and when “sedated” may produce anti-stress and anti-anxiety effects.

GB-37 stimulates the visual processing center of the brain. It also produces opposite responses from PC-6 and PC-7, possibly corresponding to the yin / yang relationship between the Liver and Gallbladder.

    • GB-37 stimulation showed increased responses in the occipital cortex (visual processing center), perhaps explaining its function on vision-related disorders.
  • GB-37 produced opposite (negative) hemodynamic responses as PC-6 and PC-7 (positive). This is shown in the figure above, where PC-6 and PC-7 show decreased brain activity patterns in orange, and GB-37 show increased brain activity patterns in blue. The authors postulate that “acupuncture stimulation at certain acupoints belonging to different channels can elicit prominently opposite neural responses.

Neurological effects of acupuncture endure post-stimulation.

  • FMRIs’ showed that acupuncture-associated modulatory effects sustained past the stimulation phase, indicating a prolonged action of acupuncture. Interestingly, signal changes in certain areas of the brain were higher after needle stimulation.

FMRIs may show how each acupoint has a specific function.

  • Stimulation of PC-7 produced signal decreases in similar areas as PC-6, but to a lesser degree and spacial extent. This may support the idea of the specific affects of each acupuncture point.

Reference Bai, L., Yan, H., Li, L., Qin, W., Chen, P., Liu, P., . . . Tian, J. (2009). Neural specificity of acupuncture stimulation at pericardium 6: Evidence from an FMRI study. J. Magn. Reson. Imaging Journal of Magnetic Resonance Imaging, 71–77.

Featured Image: Bai, L., Yan, H., Li, L., Qin, W., Chen, P., Liu, P., . . . Tian, J. (2009). Neural specificity of acupuncture stimulation at pericardium 6: Evidence from an FMRI study. J. Magn. Reson. Imaging Journal of Magnetic Resonance Imaging, 71–77.

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