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Acoustic deprivation modulates central gain in human auditory brainstem and cortex
Peter Hutchison1, Hannah Maeda1, Craig Formby1
1Department of Communication Sciences and Disorders, University of South Florida, 4202 E. Fowler Ave., PCD 1017, Tampa, FL 33620, USA.
Hearing Research
|January 4, 2023
Summary
Temporary hearing loss from earplugs triggers brainstem and cortical adaptations. The auditory system shows homeostatic plasticity, adjusting central gain and activity in response to reduced sound input.
Area of Science:
- Neuroscience
- Auditory System Plasticity
- Sensory Adaptation
Background:
- The auditory system exhibits homeostatic plasticity, adapting to hearing loss through central gain modulation.
- Earplugging is a method to induce temporary hearing loss and study these adaptive changes.
Purpose of the Study:
- To investigate central gain modulation in response to unilateral earplug-induced hearing loss.
- To assess changes in acoustic reflex threshold (ART), loudness perception, and 40 Hz auditory steady-state response (ASSR).
Main Methods:
- Young, normal-hearing adults wore a unilateral earplug for two weeks.
- Measurements included ART, loudness perception, and source-localized cortical 40 Hz ASSR.
Main Results:
- Acoustic reflex threshold decreased by 8-10 dB, indicating brainstem adaptation.
- Loudness perception showed modest increases after one week, but not two.
- Cortical 40 Hz ASSR revealed significant, asymmetrical changes in magnitude and hemispheric laterality.
Conclusions:
- Unilateral earplugging induces homeostatic plasticity in the brainstem and cortex.
- Findings suggest increased central gain in the brainstem and reduced ipsilateral cortical activity.
- ART and 40 Hz ASSR are sensitive measures for studying central gain modulation.
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