Diffusion tensor imaging and MR morphometry of the central auditory pathway and auditory cortex in aging.

Area of Science:

• Neuroscience
• Audiology
• Radiology

Background:

• Age-related hearing loss (presbycusis) is primarily attributed to inner ear dysfunction.
• Emerging evidence suggests a significant central nervous system component contributes to presbycusis.

Purpose of the Study:

• To investigate the structural integrity of the central auditory system in elderly individuals with varying degrees of presbycusis.
• To differentiate age-related changes from hearing-loss-specific alterations in the brain's auditory pathways.

Main Methods:

• Utilized 3T MRI morphometry and diffusion tensor imaging (DTI) on young controls, elderly with mild presbycusis, and elderly with severe presbycusis.
• Performed cortical reconstruction, volumetric segmentation, and auditory pathway tractography.
• Analyzed gray matter volume, gyrus surface area, cortical thickness, and DTI parameters (L1, L2L3).

Main Results:

• Elderly subjects showed significantly reduced gray matter volume and surface area in key auditory regions (Heschl's gyrus, planum temporale) compared to young controls.
• Aging correlated with increased axial diffusion (L1) in the central auditory pathway, particularly on the left side.
• Severe hearing loss showed a trend towards increased radial diffusion (L2L3) in white matter beneath Heschl's gyrus.

Conclusions:

• Structural changes occur in the central auditory system with aging, beyond peripheral inner ear decline.
• These central auditory system alterations appear largely independent of the severity of age-related hearing loss.