Connectivity-Based Topographical Changes of the Corpus Callosum During Aging

Area of Science:

• Neuroscience
• Neuroimaging
• White Matter Anatomy

Background:

• The corpus callosum (CC) is crucial for interhemispheric communication and cognitive functions, which decline with age.
• Understanding CC's region-specific topography and microstructural heterogeneity is key to cognitive health and disease research.
• Age-related changes in CC connectivity and its role in functional networks remain largely unexplored.

Purpose of the Study:

• To map the topographical organization of the corpus callosum (CC) in relation to functional brain networks.
• To investigate age-related microstructural and connectivity changes across different CC subregions.
• To establish a baseline for understanding age-associated alterations in callosal connections.

Main Methods:

• Diffusion tractography applied to 1,086 healthy individuals (21-90 years) to delineate seven CC subregions based on cortical network connections.
• Calculation of quantitative diffusion indices (e.g., FA, MD, RD, AD) and connection probability for each subregion.
• Analysis of microstructural differences and age-related trends within CC subregions.

Main Results:

• Probabilistic topography revealed distinct CC subregions associated with specific functional networks (DMN, LN, FPN, VA, SM, DA, VIS).
• Anterior CC subregions showed lower FA and higher MD/RD compared to posterior subregions, indicating microstructural differences.
• All CC subregions exhibited age-related microstructural changes, with anterior regions showing more pronounced alterations than posterior regions.

Conclusions:

• This study successfully mapped functional network topography within the corpus callosum (CC).
• An overall anterior-to-posterior trend of age-related microstructural and connectivity changes was identified in the CC.
• Findings provide a foundational understanding of CC aging, aiding in the identification of callosal connection states over time.