The Modulation of Reward and Habit Systems by Acupuncture in Adolescents with Internet Addiction

Abstract

Purpose: Acupuncture is an effective therapy for Internet addiction (IA). However, the underlying mechanisms of acupuncture in relieving compulsive Internet use remain unknown. Neuroimaging studies have demonstrated the role of the ventral striatum (VS) in the progress of IA; hence, the aim of this study was to explore the effects of acupuncture on the resting-state functional connectivity (rsFC) and relevant network of VS in IA.

Methods: Twenty-seven IA individuals and 30 demographically matched healthy control subjects (HCs) were recruited in this study. We acquired the functional magnetic resonance imaging (fMRI) data in IA subjects before and after 40 days of acupuncture treatment. Seed-to-voxel and ROI-to-ROI analyses were applied to detect the rsFC alterations of the VS and related network in IA subjects and to investigate the modulation effect of acupuncture on the rsFC.

Results: Compared with HCs, IA subjects exhibited enhanced rsFC of the right ventral rostral putamen (VRP) with the left orbitofrontal cortex (OFC), premotor cortex (PMC), cerebellum, and right ventromedial prefrontal cortex (vmPFC). In the network including these five ROIs, IA also showed increased ROI-to-ROI rsFC. Using a paired t-test in IA subjects before and after 40 days of acupuncture, the increased ROI-to-ROI rsFC was decreased (normalized to HC) with acupuncture, including the rsFC of the right VRP with the left OFC, PMC, and cerebellum, and the rsFC of the left cerebellum with the left OFC, PMC, and right vmPFC. Furthermore, the change in rsFC strength between the right VRP and left cerebellum in IA individuals was found positively correlated with the Internet craving alleviation after acupuncture.

Conclusions: These findings verified the modulation effect of acupuncture on functional connectivity of reward and habit systems related to the VS in IA individuals, which might partly represent the underlying mechanisms of acupuncture on IA.

Figure 1

Significant intergroup differences in seed-to-voxel resting-state functional connectivity of the right ventral rostral striatum between the Internet addiction individuals and healthy control subjects. Compared with healthy control subjects, individuals with IA exhibited increased resting-state functional connectivity of the right ventral rostral putamen in the left cerebellum, premotor cortex, orbitofrontal cortex, and right ventromedial prefrontal cortex.

Figure 2

ROI-to-ROI rsFC analysis between IA subjects and HCs at baseline and between pre- and posttreatment in IA individuals. (1) Red solid line: compared with HCs, IA adolescents exhibited increased rsFC of the right VRP with the left PMC, OFC, cerebellum, and right vmPFC, as well as enhanced rsFC of the left cerebellum with the left PMC, OFC, and right vmPFC at baseline. Higher rsFC of the right vmPFC with the left OFC and PMC were also observed. (2) Blue solid line: after treatment, the rsFC of the right VRP with the left PMC, OFC, and cerebellum in IA subjects were reduced, as well as the rsFC of the left cerebellum with the left PMC, OFC, and right vmPFC. rsFC: resting-state functional connectivity; IA: Internet addiction; HCs: healthy control subjects; L: left; R: right; VRP: ventral rostral putamen; PMC: premotor cortex; OFC: orbitofrontal cortex; vmPFC: ventromedial prefrontal cortex; CER: cerebellum.

Figure 3

Partial correlation between rsFC changes and clinical improvement after treatment. After controlling for gender, age, and years of education, the rsFC change between the right VRP and left cerebellum in the IA group was positively correlated with the VAS score improvement after treatment. rsFC: resting-state functional connectivity; IA: Internet addiction; VRP: ventral rostral putamen; VAS: visual analogue scale.