Age-related decline in temporal sound processing: insights from envelope steepness map in the mouse auditory cortex

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Sensory Processing

Background:

• Speech perception relies on processing temporal aspects of sound, like envelope steepness.
• The auditory cortex contains tonotopic maps and an orthogonal envelope steepness map.
• Age-related changes in auditory processing are not fully understood.

Purpose of the Study:

• To investigate age-related changes in the auditory cortex's ability to encode sound envelope steepness.
• To determine if the sensitivity to temporal sound features diminishes with age in mice.

Main Methods:

• Transcranial macroscale calcium imaging was used to record auditory cortex responses in mice.
• Responses to varying sound rise-ramp times were analyzed across different age groups (young vs. aged mice).
• Normalized distances between response peaks for different rise-ramp times were calculated.

Main Results:

• Aged mice (6-12 months) showed significantly less steep regression lines compared to young mice (1-3 months).
• This indicates a reduced ability in aged mice to differentiate between rise-ramp times.
• The effect was observed in both the anterior and primary auditory fields.

Conclusions:

• Older mice exhibit impaired ability to separate distinct sound rise-ramp times.
• This deficit in temporal processing may underlie age-related declines in speech perception.
• Findings suggest specific cortical mechanisms contributing to age-related auditory processing decline.