Modulatory effects of actual and imagined acupuncture on the functional connectivity of the periaqueductal grey and ventral tegmental area.

Abstract

OBJECTIVE\nBoth acupuncture and guided imagery hold promise for treating pain. The mechanisms underlying these alternative interventions remain unclear. The reported study aimed to comparatively investigate the modulation effect of actual and imagined acupuncture on the functional connectivity of descending pain modulation system and reward network.\n\n\nMETHODS\nTwenty-four healthy participants (mean [SE], 25.21 [0.77] years of age; 66.67% female) completed a crossover study that included five sessions, a training session and four intervention sessions administered in randomized order. We investigated the modulation effect of real acupuncture, sham acupuncture, video-guided acupuncture imagery treatment (VGAIT) and VGAIT control on the resting state functional connectivity (rsFC) of periaqueductal gray (PAG) and ventral tegmental area (VTA). These are key regions of the descending pain modulatory system (DPMS) and dopaminergic reward system, respectively.\n\n\nRESULTS\nCompared with sham acupuncture, real acupuncture produced decreased PAG-precuneus (Pcu) rsFC and increased VTA-amygdala/hippocampus rsFC. Heat pain threshold changes applied on the contralateral forearm were significantly associated with the decreased PAG-Pcu (r = 0.49, p = 0.016) and increased VTA-hippocampus rsFC (r = -0.77, p < 0.001).Compared to VGAIT control, VGAIT produced decreased PAG-paracentral lobule (PCL)/posterior cingulate cortex/Pcu, middle cingulate cortex (MCC), and medial prefrontal cortex rsFC, and decreased VTA-caudate and MCC rsFC.Direct comparison between real acupuncture and VGAIT showed that VGAIT decreased rsFC in PAG-PCL/MCC, VTA-caudate/anterior cingulate cortex/nucleus accumbens, and VTA-MCC.\n\n\nCONCLUSIONS\nResults suggest that both actual and imagined acupuncture can modulate key regions in DPMS and reward networks, but through different pathways. Identification of different pain-relief mechanisms may facilitate the development of new pain management methods.