ORIGINAL RESEARCH Internet gaming disorder: deficits in functional and structural connectivity in the ventral tegmental area-Accumbens pathway Ruonan Wang 1,2 & Min Li 1,2 & Meng Zhao 1,2 & Dahua Yu 3 & Yu Hu 1,2 & Corinde E. Wiers 4 & Gene-Jack Wang 4 & Nora D. Volkow 4,5 & Kai Yuan 1,2,3,4,6 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Dopamine projections from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) and from the substantia nigra (SN) to the dorsal striatum are involved in addiction. However, relatively little is known about the implication of these circuits in Internet gaming disorder (IGD). This study examined the alteration of resting-state functional connectivity (RSFC) and diffusion tensor imaging (DTI) -based structural connectivity of VTA/SN circuits in 61 young male participants (33 IGD and 28 healthy controls). Correlation analysis was carried out to investigate the relationship between the neuroimaging findings and the behav- ioral Internet Addiction Test (IAT). Both the NAc and medial orbitofrontal cortex (mOFC) showed lower RSFC with VTA in IGD subjects compared with controls. Moreover, the RSFC strength of VTA-right NAc and VTA-left mOFC correlated nega- tively with IAT in IGD subjects. The IGD subjects also showed lower structural connectivity in bilateral VTA-NAc tracts compared with controls, but the connectivity did not correlate with IAT in IGD. We provide evidence that functional and structural connectivity of the VTA-NAc pathway, and functional connectivity of the VTA-mOFC pathway are implicated in IGD. Since these pathways are important for dopamine reward signals and salience attribution, the findings suggest involvement of the brain DA reward system in the neurobiology of IGD. The association of functional but not structural connectivity of VTA circuits with IAT suggests that while lower structural connectivity might underlie vulnerability for IGD, lower functional connectivity may modulate severity. These results strengthen the evidence that IGD shares similar neuropathology with other addictions. Keywords Internet gaming disorder . Resting-state functional connectivity . Substantia nigra . Ventral tegmental area circuit . White matter tracts Introduction Internet game disorder (IGD) is a serious and growing public health problem, especially in adolescents (Murali and George 2007; Young 1998; Yuan et al. 2011). In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM- V) (American Psychiatric Association), IGD has been identi- fied as a condition warranting more research before it might be considered for inclusion as a formal disorder (Petry and O'brien 2013; Zastrow 2017; Markey and Ferguson 2017). Growing evidence has demonstrated that IGD and substance use disorder (SUD) share similar symptoms, including crav- ing, compulsivity, withdrawal and cognitive control deficits (Yuan et al. 2017b). Furthermore, similar neural mechanisms underlying SUD and IGD have been described, particularly for dopaminergic (DA) dysfunctions and reward, i.e., reduced availability of striatal DA D2 receptors (Kim et al. 2011) and * Kai Yuan kyuan@xidian.edu.cn 1 School of Life Science and Technology, Xidian University, Xi’an, Shaanxi 710071, People’s Republic of China 2 Engineering Research Center of Molecular and Neuro Imaging Ministry of Education, Xi’an, People’s Republic of China 3 Inner Mongolia Key Laboratory of Pattern Recognition and Intelligent Image Processing, School of Information Engineering, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, People’s Republic of China 4 National Institute on Alcoholism and Alcohol Abuse, National Institutes of Health, Bethesda, MD 20892, USA 5 National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA 6 Guangxi Key Laboratory of Multi-Source Information Mining and Security, Guangxi Normal University, Guilin, People’s Republic of China Brain Imaging and Behavior https://doi.org/10.1007/s11682-018-9929-6