| Abstract: | Background: Sham acupuncture as well as real acupuncture, a specific form of needling, is known to reduce low back pain(LBP), but the brain mechanism of placebo effect in sham acupuncture has not been clearly understood.We devised a novel form of sham acupuncture, so called phantom acupuncture which induces needling credibility without somatosensory needling.And we aimed to dissociate the brain correlates with somatosensory needling and needling credibility effect.Methods: Thirty LBP patients were randomized into the real(REAL, n=15) and phantom acupuncture(PHNT, n=15) groups.Sensory threshold and LBP intensity(VAS) were measured before and after the fMRI scanning.During the scanning, two steady state pain sessions were scanned before and after acupuncture stimulation(using low-back extension pain-model) and pain intensity(PAIN) induced by the pain model was collected.In acupuncture session, the REAL group got real acupuncture, while the PHNT group got only the visual stimulation(recorded needling manipulation video) to create needling credibility.Autonomic response of heart rate(HR) and skin conductance(SC), and acupuncture sensation were measured.Results: There was greater SC response, acupuncture sensation, signal increase in sensorimotor network(SMN), periaqueductal grey(PAG) and nucleus accumbense(NAC), and greater signal decrease in default mode network(DMN) in the REAL group.Also increase in vibration detection threshold and decrease in PAIN were observed.The HR decrease and signal increase in salience network(SLN), as well as the decrease in pressure pain threshold and unpleasantness of PAIN were observed both in the REAL and PHNT group.In the PHNT group, decrease in VAS was found.Different correlation between the change in outcome measure and the change in resting state network connectivity was found.Conclusion: Physical information processing and placebo/analgesic brain area were involved in somatosensory needling effect, while cognitive processing was related to the needling credibility effect. |
