Auditory and non-auditory effects of asymmetrical hearing loss in animal models

Abstract

Animal models offer an opportunity to investigate the consequences of asymmetrical hearing loss with a level of control over extraneous variables that is not possible with human listeners. Experimental manipulations to induce unilateral conductive or sensorineural hearing loss in animal models have demonstrated substantial and diverse changes in physiological function, anatomical reorganization of neural projections, and adverse effects on auditory behaviors. Our experiments in rodents exposed to acoustic trauma with one ear plugged result in asymmetrical hearing loss and abnormal auditory brainstem response waveforms that occur when either the unprotected or protected ear is stimulated. Susceptibility to auditory brainstem response deficits appears to differ between the right and left sides. Asymmetrical hearing loss is associated with increased startle reactivity to loud sounds, suggesting abnormal loudness perception or an increased emotional response to sound. These animals also show abnormal social interaction, and some subjects show reduced exploratory behavior in a novel environment indicative of heightened anxiety. These studies provide a framework for investigating the interplay between the auditory and non-auditory behavioral consequences of hearing loss, as well as the underlying neuropathology.Animal models offer an opportunity to investigate the consequences of asymmetrical hearing loss with a level of control over extraneous variables that is not possible with human listeners. Experimental manipulations to induce unilateral conductive or sensorineural hearing loss in animal models have demonstrated substantial and diverse changes in physiological function, anatomical reorganization of neural projections, and adverse effects on auditory behaviors. Our experiments in rodents exposed to acoustic trauma with one ear plugged result in asymmetrical hearing loss and abnormal auditory brainstem response waveforms that occur when either the unprotected or protected ear is stimulated. Susceptibility to auditory brainstem response deficits appears to differ between the right and left sides. Asymmetrical hearing loss is associated with increased startle reactivity to loud sounds, suggesting abnormal loudness perception or an increased emotional response to sound. These animals also show abnormal social i...