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Acoustic experience alters the aged auditory system
Jeremy G Turner1, Jennifer L Parrish, Loren Zuiderveld
1Department of Surgery/Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA. jturner@siumed.edu
Ear and Hearing
|October 23, 2012
Summary
Exposure to an augmented acoustic environment (AAE) in aged mice alters auditory systems, showing sex-specific changes and retaining brain plasticity. This research offers insights into potential changes from hearing aid use in older adults.
Area of Science:
- Auditory Neuroscience
- Gerontology
- Neuroplasticity
Background:
- Presbyacusis, or age-related hearing loss, is common in the elderly.
- Hearing aids are used to treat hearing loss, but the brain's response to sound stimulation late in life is not well understood.
- This study models the effects of sound exposure on the aging auditory system.
Purpose of the Study:
- To investigate the effects of an augmented acoustic environment (AAE) on the auditory system of aged mice.
- To examine sex-specific changes in auditory function and neurochemistry following AAE exposure.
- To explore the potential for plasticity in the aging auditory system.
Main Methods:
- Aged male and female CBA/CaJ mice were exposed to a low-level AAE (70 dB SPL broadband noise) for 6 weeks.
- Control groups were maintained in normal vivarium conditions.
- Auditory brainstem response thresholds, cochlear hair cell counts, and gamma-aminobutyric acid (GABA) neurochemistry in central auditory structures were measured.
Main Results:
- AAE exposure induced sex-specific alterations in cochlear pathology, auditory thresholds, and GABA neurochemistry.
- Males showed improved thresholds and less hair cell loss, while females showed the opposite.
- Glutamic acid decarboxylase (GAD67) levels increased in the inferior colliculus for both sexes; however, primary auditory cortex showed increased GAD67 in females and decreased GAD67 in males.
Conclusions:
- Low-level AAE exposure alters peripheral and central auditory systems in aged mice, with sex-dependent effects.
- These changes interact with sex and pre-existing hearing loss.
- The aged brain demonstrates significant anatomical, electrophysiological, and neurochemical plasticity, suggesting potential benefits from interventions like hearing aids.
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