Akademik Veri Yönetim Sistemi
BRAIN MECHANISMS, cilt.153, 2026 (SCI-Expanded)
Study Design: Cross-sectional study Objective: Interhemispheric connectivity is fundamental for integrative brain function, yet whether callosal pathways exhibit uniform vulnerability or distinct structural signatures across the adult lifespan remains unclear. This study investigated the region-specific microstructural and morphometric trajectories of three major corpus callosum (CC) tracts forceps minor, callosal body, and forceps major and evaluated their predictive utility for brain age estimation using machine learning. Design: Retrospective diffusion MRI data from 62 healthy adults (aged 18-60 years) were analyzed. Methods: Deterministic tractography was performed to segment CC sub-tracts automatically via the JHU White Matter Atlas. Comprehensive metrics, including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), tract volume normalized by brain mask volume (vol), tract count, mean tract length (mm), total tract volume (mm(3)), and total tract surface area (mm(2)), were extracted. Brain Age was estimated using linear and regularized regression models (Elastic Net) to handle multicollinearity. Results: Callosal subregions exhibited significant structural heterogeneity (p < .001), with the longest streamlines observed in the forceps major. We identified a distinct, region-specific pattern in which anterior and central pathways showed greater age-related change than posterior pathways. The forceps minor and callosal body exhibited significant age-related alterations, with the 'vol' of the callosal body showing the strongest association (r = 0.653, p < .001), consistent with a marker of fiber dispersion rather than hypertrophy. In contrast, the forceps major demonstrated structural resilience with preserved surface area and microstructure. Elastic Net regression achieved high predictive accuracy (R-2 = 0.67, RMSE = 6.30 years), identifying these dispersion signatures as key predictors. Conclusion: The CC does not age uniformly; instead, it shows a region-specific pattern in which anterior and central pathways are more susceptible to microstructural change, whereas posterior pathways remain comparatively stable in adulthood. Tractography-derived metrics, particularly those reflecting fiber dispersion, capture meaningful age related variation and show potential as anatomically grounded indicators of neurobiological aging.