Figure 1.

Experimental design. (A) Location of ST36 and Control points on the right leg (view from the front and from the back, figure adapted Drake et al., 2009). (B) Experiment design of EEG measurement. On each of the 3 randomized measurement days EEG was recorded for every subject in a sitting position, with open eyes over a 25.5-min period. After the first 5-min baseline, an acupuncture needle was inserted and was stimulated manually at a time point 5 and 10 min after insertion. After a further 5 min the needle was removed and the EEG was recorded for a further 5 min without the needle. After the measurement, individual needle sensation was measured with a questionnaire. (C) Experiment design of fMRI measurement. In the fMRI scanner each subject was told to lie relaxed, in a supine position, with open eyes and to concentrate on the sensation caused by the needle stimulation. After the first resting-state was scanned for 6 min, an acupuncture needle was inserted into one point according to the randomized intervention order. The needle was then immediately stimulated manually according to the event-related design. After 6 min intermittent manipulation, the needle was withdrawn and a resting-state scan was continued for 6 min, and then followed by a 4-min break for the subject without scanning. The same scan procedure was then applied for the other two interventions on the other two points. But for the third intervention, there was no 4-min break. After each post-intervention resting-state scan individual needle sensation was measured with questionnaires.