Background and aims: The shift from goal-directed to habitual control is a well-documented phenomenon in addiction research and is considered a critical factor in the development and maintenance of addictive behaviors. Whether Internet Gaming Disorder (IGD) is also associated with such a shift is not yet clear. The current study investigated the imbalance between goal-directed and habitual control in individuals with IGD. Methods: Goal-directed and habitual control, as informed by model-based (MB) and model-free (MF) learning, were assessed with a two-step sequential decision-making task during functional magnetic resonance imaging (fMRI) in 33 young adults with IGD and 32 healthy controls (HCs). Self-report data regarding addictive symptoms, game craving, and impulsivity were also collected. Results: Individuals with IGD relied more heavily on habitual control to guide subsequent choices compared to HCs. According to a hybrid reinforcement learning model, individuals with IGD also exhibited a reduced MB weight related to HCs, which was correlated with more severe addictive symptoms. fMRI results revealed that individuals with IGD showed increased MF reward prediction error (RPE _MF ) signals in the right triangular part of the inferior frontal gyrus (IFG). No significant group differences were found in the contrast of RPE _MB maps. Discussion and conclusions: Our study provides both behavioral and neural evidence highlighting an imbalance between goal-directed and habitual control, favoring habitual control in individuals with IGD. This imbalance is associated with the severity of addictive symptoms, suggesting an indication of habit inclination in IGD could potentially contribute to the development or maintenance of the addiction.

This network meta-analysis was conducted to compare the predictive value of eight SNPs on the efficacy of antidepressants in major depressive disorder (MDD), including 5-HTTLPR, 5HTR2A (rs6311, rs6...