Age- and Sex- Dependent Differences in Peripheral and Central Auditory Processing
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| Pubblicato in: | ProQuest Dissertations and Theses (2025) |
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| Abstract: | Age-related hearing loss, or presbycusis, is a widespread sensory disorder associated with diminished quality of life and increased risk of cognitive decline, with limited treatment options. While presbycusis is often identified by elevated hearing thresholds, more subtle deficits in auditory temporal processing and speech recognition also emerge with age and may go undetected by standard audiometric tests. Sex differences in peripheral auditory function have been well studied, but very little is known regarding sex differences in central auditory processing as humans age. Not considering sex differences when treating presbycusis may reduce intervention efficacy. Nicotinic acetylcholine receptor modulation has been suggested as a potential treatment for improving auditory function, but it is unclear if nicotine affects auditory responses in an age- and sex- dependent manner. To address these gaps, we designed a series of experiments to identify nicotine’s effect on sex- and age-dependent differences in auditory brainstem responses, to determine if sex- and age-differences are present in cortical laminar processing, and to investigate whether cortical processing fluctuates with the estrus cycle. Lastly, to address the mechanism behind age-related disruption in temporal processing, we designed an experiment looking at whether the removal of perineuronal nets (PNNs) in the auditory cortex would lead to a decrease in temporal fidelity. Several key findings were made. We confirmed age-related reduction of hearing sensitivity and found that acute nicotine treatment improves hearing sensitivity at high frequencies. Age-related deficits in cortical processing are both sex- and layer specific. There are no sex differences in cortical temporal processing in young mice, but sex differences emerge in old cortical temporal processing, mainly due to the steep decline occurring in post-menopausal females. Cortical temporal processing does not change during high and low estrogen, suggesting no acute involvement of hormones. Lastly, PNNs caused a decline in temporal processing, however only after full recovery, suggesting acute shaping of auditory cortical responses is less dependent on PNNs, but long-term stability of responses following a circuit perturbation depends on the integrity of PNNs. Therefore, loss of cortical PNNs with age, may impact auditory temporal processing. Together, these findings demonstrate that aging impairs auditory processing across multiple levels of the auditory system in a sex dependent manner. Additionally, these findings highlight the need for sex-stratified analyses in clinical audiology when developing treatment options. |
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| ISBN: | 9798263309619 |
| Fonte: | ProQuest Dissertations & Theses Global |