Expertise-related right frontal structural differences in older professional Go players: network and inter-hemispheric covariance analyses.

Professional Go (Baduk) is a rare model of lifelong cognitive expertise that taxes strategic planning and working memory. Prior Go studies examined younger or amateur players and isolated regions (Jung et al., 2013); whether professional practice leaves a network-level structural signature in older experts is unknown. To our knowledge, this is the first characterization in an older professional cohort, extending beyond regional measures to network morphometry and inter-hemispheric covariance. We used T1-weighted structural MRI to compare 29 older male professional Go players (PGP; mean career 54.6 years; dan 5-9) with 50 male controls (CTRL) recruited at baseline of a Go-training trial (KCT0010704). Groups were comparable in age and vascular risk, although CTRL had more education (15.9 vs 12.4 years). Regional gray-matter volume, thickness, and texture were aggregated into six Yeo functional-network regions, and inter-hemispheric structural covariance was computed. PGP showed larger executive control network (ECN) volume (η²p = 0.153; PFDR = 0.006), driven by the right middle frontal gyrus (MFG; η²p = 0.392; PFDR < 0.001). The right MFG effect held across education-adjusted ANCOVA, propensity-score matching, and a cognitively-normal subgroup (n = 62); ECN persisted in the subgroup but did not survive strict matching in the full sample. Covariate-adjusted inter-hemispheric covariance was higher in PGP in five of six networks (all PFDR < 0.05). Cognition was domain-specific rather than globally superior: PGP excelled at working memory (+0.71 SD) but underperformed at naming (-0.82 SD; Group × Domain P < 0.001). The enlarged right MFG, robust to education adjustment, is the principal, association-level finding, motivating longitudinal follow-up.