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.