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Perceptual Consequences of Cochlear Deafferentation in Humans.
Naomi F Bramhall1,2, Garnett P McMillan1
1VA National Center for Rehabilitative Auditory Research, Veterans Affairs Portland Health Care System, Portland, OR, USA.
Trends in Hearing
|May 13, 2024
Summary
Cochlear synaptopathy, or deafferentation, is linked to aging and noise exposure in animals and humans. This auditory dysfunction may cause tinnitus and speech perception difficulties.
Area of Science:
- Auditory Neuroscience
- Otoacoustic Emissions
- Neuroscience
Background:
- Cochlear synaptopathy, a form of cochlear deafferentation, is observed in animal models due to age and noise exposure.
- Evidence suggests this auditory dysfunction also occurs in humans from aging and occupational/military noise exposure.
Purpose of the Study:
- To investigate the perceptual consequences of cochlear synaptopathy in humans.
- To explore the relationship between deafferentation and auditory dysfunction such as tinnitus, hyperacusis, and speech-in-noise perception.
Main Methods:
- Analysis of temporal bone and auditory physiological data in humans.
- Review of animal data on deafferentation effects.
- Comparison of human physiological correlates of deafferentation with perceptual outcomes.
Main Results:
- Animal data indicate deafferentation leads to increased central gain, tinnitus, abnormal loudness perception, and impaired temporal/signal-in-noise processing.
- Human physiological data support a link between deafferentation, increased central gain, and tinnitus.
- Human data on deafferentation and hyperacusis are limited; speech-in-noise perception findings are mixed, potentially due to non-linear relationships and study variations.
Conclusions:
- Cochlear synaptopathy is a plausible cause of tinnitus and potentially hyperacusis and speech-in-noise difficulties in humans.
- Further research is needed to clarify the relationship between deafferentation and hyperacusis.
- Mixed findings on speech-in-noise perception may be reconciled by considering non-linear effects and study heterogeneity.
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