Imaging the Functional Connectivity of the Periaqueductal Gray during Genuine and Sham Electroacupuncture Treatment

Abstract

BackgroundElectroacupuncture (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.ResultsForty-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.ConclusionsOur 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.

Electroacupuncture improves cognitive ability following cerebral ischemia reperfusion injury via CaM-CaMKIV-CREB signaling in the rat hippocampus

“…This therapeutic method originated in China >2,000 years ago, and over time EA has been accepted as conventional medicine in clinical practice worldwide (1)(2)(3)(4). Statistical analyses of clinical results have indicated that the effects of EA on strokes are significant (5).…”

Acupuncture-Induced Pain Relief and the Human Brain’s Default Mode Network – an Extended View of Central Effects of Acupuncture Analgesia

“…As shown by Zyloney et al [35], EA leads to enhanced functional connectivity between precuneus, which shows the highest glucose consumption within the DMN, and periaqueductal gray [31]. The former is related to self-referential processing, the latter plays an important role in endogenous analgesia and is stimulated by AA [8,[36][37][38][39].…”

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