title: Imaging the functional connectivity of the Periaqueductal Gray during genuine and sham electroacupuncture treatment.
abstract: BACKGROUND
  Electroacupuncture (EA) is currently one of the most popular acupuncture modalities. However, the continuous stimulation characteristic of EA treatment presents challenges to the use of conventional functional Magnetic Resonance Imaging (fMRI) approaches for the investigation of neural mechanisms mediating treatment response because of the requirement for brief and intermittent stimuli in event related or block designed task paradigms. A relatively new analysis method, functional connectivity fMRI (fcMRI), has great potential for studying continuous treatment modalities such as EA. In a previous study, we found that, compared with sham acupuncture, EA can significantly reduce Periaqueductal Gray (PAG) activity when subsequently evoked by experimental pain. Given the PAG's important role in mediating acupuncture analgesia, in this study we investigated functional connectivity with the area of the PAG we previously identified and how that connectivity was affected by genuine and sham EA.
  
  
  RESULTS
  Forty-eight subjects, who were randomly assigned to receive either genuine or sham EA paired with either a high or low expectancy manipulation, completed the study. Direct comparison of each treatment mode's functional connectivity revealed: significantly greater connectivity between the PAG, left posterior cingulate cortex (PCC), and precuneus for the contrast of genuine minus sham; significantly greater connectivity between the PAG and right anterior insula for the contrast of sham minus genuine; no significant differences in connectivity between different contrasts of the two expectancy levels.
  
  
  CONCLUSIONS
  Our findings indicate the intrinsic functional connectivity changes among key brain regions in the pain matrix and default mode network during genuine EA compared with sham EA. We speculate that continuous genuine EA stimulation can modify the coupling of spontaneous activity in brain regions that play a role in modulating pain perception.
authors.affiliation: Department of Psychiatry, Massachusetts General Hospital, Charlestown, USA. czyloney@gmail.com
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Zyloney
authors.forename: Karin
authors.initials: K
authors.lastname: Jensen
authors.forename: Ginger
authors.initials: G
authors.lastname: Polich
authors.forename: Rita E
authors.initials: RE
authors.lastname: Loiotile
authors.forename: Alexandra
authors.initials: A
authors.lastname: Cheetham
authors.forename: Peter S
authors.initials: PS
authors.lastname: LaViolette
authors.forename: Peichi
authors.initials: P
authors.lastname: Tu
authors.forename: Ted J
authors.initials: TJ
authors.lastname: Kaptchuk
authors.forename: Randy L
authors.initials: RL
authors.lastname: Gollub
authors.forename: Jian
authors.initials: J
authors.lastname: Kong
mesh_terms: D015667:Acupuncture Analgesia / Q000379:methods; D000328:Adult; D001931:Brain Mapping; D015671:Electroacupuncture / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009434:Neural Pathways / Q000502:physiology*; D058748:Pain Perception; D010487:Periaqueductal Gray / Q000502:physiology* / Q000503:physiopathology; D010919:Placebos; D055815:Young Adult
chemical_list: D010919:Placebos