Authors:

Emily Bell

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About Paper:

Noise-induced hearing loss (NIHL) results from loud, harmful noises, often experienced by military service members. The auditory system consists of the peripheral and central auditory systems (PAS, CAS). Previous studies have suggested the PAS is more susceptible to noise-induced damage, requiring injury to structures preceding the auditory nerve (AN), such as the cochlea and hair cells. CAS damage involves impairment following the AN, influencing inhibitory and excitatory neural transmission. While damage to the PAS is commonly observed in NIHL, fewer studies have investigated the characterization of central damage. This study aims to compare peripheral and central noise-induced damage in the auditory pathway. We predict NIHL will be characterized by reduced sensitivity to low-intensity sounds, portraying increased thresholds and decreased waveform amplitudes. F-344 rodents were exposed to 13 small arms fire-like biphasic pulses over 2.5 min at ~130 dB peak SPL. Auditory evoked potential (AEP) recordings were used to measure neural population function and estimated sensitivity thresholds in response to click and pure tone stimuli (20 - 80 dB). Distortion product otoacoustic emission (DPOAE) recordings were used to measure outer hair cell functionality. To assess changes within the auditory pathway, we compared amplitudes and thresholds across days 0, 7, 14, and 28. Subsequently, preliminary analysis of the click AEPs and 2, 4, and 8 kHz DPOAEs show increased thresholds and decreased amplitudes compared to baseline, indicating reduced cochlear sensitivity. We also observed a trend in female rats exhibiting lower thresholds than males, aligning with other studies indicating unknown underlying mechanisms of neural protection.

Source:

Purdue University / 2023

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Co-authors:

Emily Bell