8Fields HL. Pain modulation: expectation t opioid analgesia and virtual pain[ J] . Prog Brain Kes, 2000,122:245 -253.
9Villemure C Bushnell MC ,treede RDtei al. Human brain mechanisms of pain pereption and reulation in health anddisease[ J]. Eur J Pain, 2005,9(4) :463 -484.