Neural Generators Underlying Temporal Envelope Processing Show Altered Responses and Hemispheric Asymmetry Across Age

Area of Science:

• Auditory Neuroscience
• Gerontology
• Speech Processing

Background:

• Speech understanding difficulties are common in older adults, despite normal hearing sensitivity.
• These issues are linked to age-related changes in central auditory temporal processing.
• Neural generators underlying temporal processing may reflect these age-related changes.

Purpose of the Study:

• To investigate age-related alterations in neural generators during auditory temporal processing.
• To examine middle-aged and older adults with normal hearing thresholds.
• To analyze responses to different acoustic modulation frequencies.

Main Methods:

• Utilized minimum-norm imaging to reconstruct cortical and subcortical neural generators.
• Assessed neural responses to slow (<50 Hz) and fast (80 Hz) acoustic modulations.
• Compared neural source strength and phase-locking between younger and older adults.

Main Results:

• Older adults showed higher response strength for slow modulations (<50 Hz) but unchanged phase-locking.
• For faster modulations (80 Hz), both response strength and phase-locking were reduced in older adults.
• Cortical and subcortical generators, as well as hemispheric asymmetry, exhibited age-related changes.

Conclusions:

• Age-related changes in auditory temporal processing, particularly in response to fast modulations, may stem from reduced functional inhibition.
• Findings highlight alterations in both cortical and subcortical neural activity and hemispheric processing.
• Understanding these neural changes is crucial for developing rehabilitation strategies for age-related speech understanding deficits.