AUTHOR=Manno Francis A. M. , Cheung Pikting , Basnet Vardhan , Khan Muhammad Shehzad , Mao Yuqi , Pan Leilei , Ma Victor , Cho William C. , Tian Shile , An Ziqi , Feng Yanqiu , Cai Yi-Ling , Pienkowski Martin , Lau Condon 

TITLE=Subtle alterations of vestibulomotor functioning in conductive hearing loss

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1057551

DOI=10.3389/fnins.2023.1057551

ISSN=1662-453X

ABSTRACT=Conductive hearing loss (CHL) attenuates the ability to transmit air conducted sounds to the ear. In humans, severe hearing loss is often accompanied by alterations to other neural systems, such as vestibular; however, the inter-relations are not well understood. The overall goal of this study is to assess vestibular-related functioning proxies in a rat CHL model. CHL of >20 dB threshold shift was induced by tympanic membrane puncture in male Sprague-Dawley rats (n = 134, 250 g, two months old). Assessment was performed using the rotarod, balance beam, elevator vertical motion (EVM) and Ferris-wheel rotation (FWR) assays. Rotarod assessment of motor function was not significantly different between pre and post-CHL (~1 week) rats for time duration (sec) or speed (RPM), albeit the former had a small effect size difference. Balance beam time to transverse was significantly longer for post-CHL rats, likely indicating a change in motor coordination. Also, failure to cross was only noted for CHL rats. The defection count was significantly reduced for CHL rats compared to control rats following FWR, but not EVM. The total distance traveled during open-field examination after EVM was significantly different between control and CHL rats, but not for FWR. The EVM is associated with linear acceleration (acting in the vertical plane: up-down) stimulating the saccule, while the FWR is associated with angular acceleration (centrifugal rotation about a circular axis) stimulating both otolith organs and semicircular canals; therefore, the difference in results could reflect the specific vestibular-organ functional role. Future studies should evaluate direct measures of vestibular functioning in rats with CHL.