Acupoints and EAS paradigm
EAS was performed at acupoints Shenting (GV24) and Touwei (ST8), and the EAS paradigm used in this study is listed in Figure (a) The location of GV24 and ST8 acupoints. (b) Paradigm of MRI scan: The whole procedure included three steps: T1WI and T2WI (before needle intervention), 1–40 scans of BOLD fMRI, and 41–70 scans of BOLD fMRIThe EAS paradigm used in this study is as follows: The day before the scan, the electrical current test was performed on the participants of group 2, and the intensity of the current which depended on the endurance of the participants was recorded. All participants were asked to stay awake and try not to think of anything during brain fMRI scanning. The participants lay on the scanner bed. First, subjects in both Group 1 and Group 2 completed T1‐weighted imaging (T1WI) and T2‐weighted imaging (T2WI) scans, which took 7 min in total. Then, the scans were suspended, and the scanner bed was subsequently moved out of the scanner. Verum and sham acupunctures were performed on Group 2 and Group 1, respectively. In Group 2, gold needles were penetrated in acupoints GV24 and ST8, and the gold needle tails were connected to an EAS equipment (GV24 with positive pole and ST8 with negative pole). The current stimulation was set to start automatically after 40 scans (2 min) of BOLD scanning with the intensity according to the test results from previous day, and the electrical stimulation lasted 30 scans (1 min and 30 s). When the experiment finished, the acupuncturist recorded the acupuncture sensation. In Group 1, the dull tail of the gold needle was used to sting the same acupoints without penetrating the skin. Then, the needles were fixed in the scalp, and the tails of the needles were connected to an EAS equipment without electrical current during 70 scans (3 min and 30 s) of BOLD fMRI. This sham needle has been validated in some studies, which demonstrated that subjects could not distinguish between verum and sham needling (Kong et al., 