Altered long-range visual hierarchical connectivity in internet gaming disorder: reduced V1-LOC connectivity and its association with addiction severity.

BACKGROUND: Neuroimaging studies of internet gaming disorder (IGD) have primarily focused on reward-related and executive-control networks. However, sensory processing of addiction-related cues, particularly visual processing, may also contribute to IGD. Whether the intrinsic hierarchical organization of the visual system is altered remains unclear. METHODS: The study included 35 individuals with IGD and 30 healthy controls (HCs), with an overall age range of 9-33 years. The sample was predominantly composed of adolescents. An a priori three-level visual hierarchy model comprising the primary visual cortex (V1), lingual gyrus, and lateral occipital cortex (LOC) was constructed. Functional connectivity (FC) was calculated for the V1-Lingual, Lingual-LOC, and V1-LOC pathways. A hierarchical integration index (HII), derived from V1-LOC and V1-Lingual connectivity, was calculated to assess long-range relative to local visual coupling. Group differences were assessed using MANCOVA with follow-up univariate analyses and FDR correction. Within the IGD group, associations between IAT scores and all visual hierarchical measures were examined using Pearson and covariate-adjusted partial correlations with FDR correction. RESULTS: V1-LOC connectivity was significantly reduced in the IGD group compared with HCs (HC: 0.364 ± 0.132; IGD: 0.130 ± 0.189; F(1,59) = 30.809; FDR-corrected p < 0.001; partial η2 = 0.343). V1-Lingual and Lingual-LOC connectivity did not show significant group differences, although their effect sizes were small-to-moderate (Cohen's d = 0.32 and 0.40, respectively). The HII was numerically lower in IGD but did not reach statistical significance (t = 1.90, p = 0.062; Cohen's d = 0.46). Within the IGD group, lower V1-LOC connectivity was associated with higher IAT scores (r = -0.479, FDR-corrected p = 0.016), and this association remained significant after controlling for age, sex, education, and mean FD (partial r = -0.447, FDR-corrected p = 0.048). CONCLUSIONS: IGD is associated with altered long-range hierarchical connectivity within the visual system, particularly between early visual cortex and higher-order LOC. These findings provide a sensory-level perspective complementing reward- and control-centered accounts of IGD.