Unravelling microstructural age-related changes in the acoustic radiations through advanced diffusion MRI analysis

Motivation: Age-related hearing loss is widespread, but the impact of aging on the central auditory pathway's structure and function is poorly understood. Goal(s): This study aims to characterise the microstructural signatures of aging in the acoustic radiations. Approach: Forty-five participants between 18-76 years underwent diffusion weighted MRI. Tractography was used to delineate each subject's acoustic radiations, and maps of diffusion MRI metrics and biophysical model parameters were computed. Results: Mean isotropic kurtosis and axonal volume were found to increase with age in the bilateral acoustic radiations. The increase in apparent axonal volume fraction contradicts previous studies and expectations of decreased fibre integrity with age. Impact: The aging-related microstructural changes to the central auditory pathway shown here may have functional consequences in terms of hearing ability and hearing rehabilitation strategies among the elderly. Future studies could incorporate electrophysiological measurements to assess this microstructure-function relationship.