The Sustained Brain Effects after Needling at Fengchi (GB20) Measured by Functional MRI

Acupuncture is a treatment method for some diseases that has been used in ancient China. Based on Traditional Chinese Medicine, each acupoint has functional specificity, so stimulation of a specific acupoint will treat specific types of diseases. Acupuncture can induce changes in the brain and, fMRI can help to investigate of brain changes induced by acupuncture. Fengchi (GB 20) is regarded as a major point for treatment of some diseases in acupuncture therapy. However, a large number of clinical studies have reported its significant curative effects, its mechanism of action is still not clear. In this study, fMRI was used to observe activity changes in the brains of 11 healthy volunteers, involved in acupuncture and tactile stimulation at GB20. For each subject, two fMRI for acupuncture and two runs for tactile stimulation were done. First resting-state scan started with 15 minutes of rest, followed by 30 seconds of acupoint stimulation, and then second fMRI was done. After 2 hours of break, the subject had the 3rd session of scan, followed by 30 seconds of stimulation at GB20, and then the 4th scan was performed. The interval between the two functional run (before and after stimulation) was 45 seconds. After finishing the 2nd and 4th scans, the psychophysical responses were questioned and scored. Our results indicated acupuncture on the left GB20 mainly produced signal changes in the right and left Parietal Lobe, right Occipital Lobe, and the specific regions including cuneus, precuneus. During acupuncture, more subjects experienced soreness, dull pain, heaviness, fullness and pressure compared with tactile stimulation (p < 0.05). Significant intensity differences (p < 0.05) were showed in soreness, dull pain, heaviness, and fullness. According to our study, there was a significant positive correlation between the increase of the Degree Centrality of the right cuneus and the total score of acupuncture sensation (R = 0.716, P = 0.03) after acupuncture stimulation. In addition, the enhancement of the functional connectivity between the bilateral posterior cingulate cortex and the left inferior parietal lobule after tactile stimulation was positively correlated with the total score of tactile stimulation sensation (R = 0.72, P = 0.029; R = 0.687, P = 0.041). This preliminary study gives evidence that acupuncture at GB20 can produce the modulation effects on the visual function and Default Mode Network involving with self-reference and memory. Results are in agreement with that GB20 regulates multiple physiological systems and may imply to accomplish a variety of empirically obvious therapeutic effects by the physiological response to acupuncture stimulation. A further question is how these results in healthy subjects can be generalized and applied to patients with disorders responsive to acupuncture.