Lifespan trajectories of the morphology and tractography of the corpus callosum: A 5.0 T MRI study.

The corpus callosum (CC) is the largest white matter fiber bundle connecting the two hemispheres, facilitating interhemispheric integration and hemispheric specialization. Neuroimaging studies have identified the CC as a marker for aging and various neuropsychiatric disorders. However, studies focusing on high-resolution imaging and detailed lifespan characterizations of CC morphology and connectivity are still limited, highlighting the need for further investigation.Utilizing the high-resolution brain imaging capabilities of 5.0 T ultra-high-field MRI, we collected lifespan data from 266 healthy adults aged 18-89. We segmented and measured the midsagittal area, circularity, thickness, and tractography of the CC using both linear regression and nonlinear fitting models. Our analysis revealed that, despite regional variations, these measures generally exhibited a brief initial increase, likely reflecting developmental maturation, followed by a rapid decline associated with aging-related degeneration. Coupling analysis further indicated that the positive correlation between CC morphology and tractography becomes stronger with increasing age, suggesting age-related structural-functional coupling. External validation and correlation with cognitive-behavioral tests showed that CC subregions with significant age-related changes predominantly involve areas connecting the frontal and parietal networks, particularly those associated with executive function and attentional control. These findings provide new insights into the lifespan evolution of CC morphology and tractography, as well as their degeneration associated with cognitive processing and sensory-motor integration.