Mapping age-related cortical laminar-specific microstructural alterations across the lifespan using high-gradient diffusion MRI

Motivation: Age-related microstructural alterations in the cortex remain poorly understood at the laminar level. Advanced diffusion MRI techniques can detect these changes to improve understanding of aging and neurodegeneration. Goal(s): This study aims to investigate laminar-specific changes associated with aging by employing high-gradient diffusion MRI and SANDI model. Approach: We applied the SANDI model to high-gradient diffusion MRI data from 72 cognitively healthy subjects and sampled 21 cortical depths. Super-resolution techniques were utilized to minimize partial volume effects, and Pearson correlation analysis was performed. Results: Age-related microstructural changes were observed across cortical layers, with middle layers showing pronounced alterations in soma and neurite fractions. Impact: This research proposes a novel approach to investigate laminar-specific cortical changes, enabling a better understanding of normal aging and identifying potential early markers of neurodegeneration. The established methodology can be applied to various neurological conditions affecting cortical microstructure.