Age-Related Cochlear Synaptopathy: An Early-Onset Contributor to Auditory Functional Decline
By Y. Sergeyenko, K. Lall, M. Liberman, S. Kujawa. Journal of Neuroscience, 2013
731 citations recorded by the source corpus.
Aging listeners experience greater difficulty understanding speech in adverse listening conditions and exhibit degraded temporal resolution, even when audiometric thresholds are normal. When threshold evidence for peripheral involvement is lacking, central and cognitive factors are often cited as underlying performance declines. However, previous work has uncovered widespread loss of cochlear afferent synapses and progressive cochlear nerve degeneration in noise-exposed ears with recovered thresholds and no hair cell loss (Kujawa and Liberman 2009). Here, we characterize age-related cochlear synaptic and neural degeneration in CBA/CaJ mice never exposed to high-level noise. Cochlear hair cell and neuronal function was assessed via distortion product otoacoustic emissions and auditory brainstem responses, respectively. Immunostained cochlear whole mounts and plastic-embedded sections were studied by confocal and conventional light microscopy to quantify hair cells, cochlear neurons, and synaptic structures, i.e., presynaptic ribbons and postsynaptic glutamate receptors. Cochlear synaptic loss progresses from youth (4 weeks) to old age (144 weeks) and is seen throughout the cochlea long before age-related changes in thresholds or hair cell counts. Cochlear nerve loss parallels the synaptic loss, after a delay of several months. Key functional clues to the synaptopathy are available in the neural response; these can be accessed noninvasively, enhancing the possibilities for translation to human clinical characterization.
Subfields: Cognitive Neuroscience, Sensory Systems, Speech and Hearing
View Paper: https://www.semanticscholar.org/paper/2a9d1286d79a9a7a8f81e62a4592b6b725f7104d
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Citations in the corpus
- Synaptopathy in the noise-exposed and aging cochlea: primary neural degeneration in acquired sensorineural hearing loss (2015, background): “…we have observed that, despite the reduction in wave 1 of the ABR in both noise-induced and age-related IHC synaptopathy, there is no reduction in the amplitude of wave 5, which is thought to arise mainly from responses in the inferior colliculus (Hickox et al., 2014; Sergeyenko et al., 2013).”