Maladaptive compensatory plasticity in unilateral hearing loss

The National Institute on Deafness and Other Communication Disorders awarded the University of Pittsburgh $108,166 on December 31, 2026, under the Research Related to Deafness and Communication Disorders program (CFDA 93.173).

The research investigates maladaptive compensatory plasticity in unilateral hearing loss, specifically addressing why individuals with normal hearing in one ear experience profound speech perception difficulties in noise despite peripheral audiometric measures suggesting minimal dysfunction. The project leverages identical EEG-based gain measurements in humans with unilateral hearing loss and in a gerbil model to establish whether central gain—a compensatory increase in neural responsiveness that may alter cortical excitation-inhibition balance—explains variability in speech perception outcomes and whether such changes are reversible with restoration of balanced auditory input. Aim 1 quantifies central gain and its relationship to speech perception performance in adults with unilateral hearing loss using EEG measures that separately index peripheral and cortical responsiveness. Aim 2 employs a reversible rodent model of unilateral hearing loss to map the emergence and recovery of central gain following controlled auditory deprivation and restoration, using identical stimuli and physiological measures to those collected in humans. The long-term goal is establishing non-invasive biomarkers for clinical assessment of hearing loss.

Performance occurs in Pittsburgh, Pennsylvania, with a period of performance ending August 31, 2028.

Abstract

& abstract unilateral hearing loss (UHL) presents a clinical paradox: despite normal hearing in one ear, affected individuals experience profound difficulties with speech perception in noise (spin). This suggests that UHL is not merely a peripheral deficit localized to the ear but also induces central auditory plasticity in ways that are poorly characterized and potentially maladaptive. Current hearing tests rely on peripheral audiometric thresholds; however, substantial variability in spin deficits in those with UHL suggests that these measures fail to capture the full extent of auditory dysfunction. Evidence from animal studies indicates that UHL triggers compensatory increases in neural responsiveness, a process referred to as central gain, which may alter cortical excitation-inhibition balance and, in turn, introduce neural noise that interferes with accurate sound encoding. However, IT remains unknown whether central gain explains the striking variability in spin outcomes observed among individuals with UHL or whether these changes are reversible with restoration of balanced input. My research addresses these gaps by leveraging an identical EEG-based gain measurement in humans with UHL and in a gerbil model of UHL to directly link auditory perception to neurophysiology and assess whether maladaptive central gain contributes to spin impairment. The long-term goal of this work is to establish non-invasive biomarkers for clinical assessment. Aim 1 will quantify central gain and its relationship to spin performance in adults with UHL using EEG-based measures that separately index peripheral and cortical responsiveness. Aim 2 will use a reversible rodent model of UHL to map the emergence and recovery of central gain following controlled auditory deprivation and restoration, using identical stimuli and physiological measures to those collected in humans in aim 1. Preliminary data from this model show robust increases in cortical responses after two weeks of unilateral earplugging, suggesting bilateral and potentially maladaptive cortical plasticity. By integrating human behavioral outcomes with harmonized physiological measures across species, this project will clarify how UHL-induced central plasticity contributes to real-world communication challenges and will identify noninvasive biomarkers capable of detecting neural dysfunction missed by traditional hearing tests. These findings will advance diagnostic precision, inform rehabilitation strategies, and improve clinical care for individuals living with UHL. The proposed work will be conducted in a multidisciplinary environment that provides comprehensive training in auditory neuroscience, electrophysiology, and translational research.