Individual-Specific Neural Subspaces Reveal Reward Dysregulation and State Transition Vulnerabilities in Internet...

Internet gaming disorder (IGD) is a clinically heterogeneous condition, yet the underlying neurobiological subtypes remain to be elucidated. Investigating subpatterns of spontaneous neural activity and state switching from individual to group patterns may provide deeper insights into the etiology of IGD.

Resting-state functional magnetic resonance imaging data were collected from 519 participants (257 with IGD, 262 recreational game users [RGUs]). The fractional amplitude of low-frequency fluctuations was computed to assess spontaneous neural activity. Nonnegative matrix factorization was used to extract features that were predictive of addiction severity. Network control theory (NCT) was utilized to quantify the energy required for brain state transitions.

Compared with RGUs, participants with IGD exhibited heightened activity in brain patterns (involving the basal ganglia and thalamic regions) associated with reward processing. The individual weight of this pattern was positively associated with addiction severity, and the spatial intensity was negatively correlated with the density of serotonin 1A (5-HT_1A) receptors. Furthermore, NCT analysis demonstrated that transitioning to a high-craving state required less control energy than transitioning to other states.

Although neural activity varies among individuals with IGD, the homogeneity can be embedded in reward processing-related brain areas. Reduction in 5-HT_1A receptor density may be a substrate for this pattern. Individuals with IGD transition more readily to high-craving states than to other states. These results elucidate neural mechanisms underlying IGD and highlight the importance of individualized approaches to treating the disorder.