# Cortical reorganization and signal-in-noise processing following asymmetric hearing loss

> **NIH NIH F32** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2021 · $72,630

## Abstract

PROJECT SUMMARY
The consequences of asymmetric peripheral dysfunction are especially profound in the auditory system, where
cochlear receptor cells are not spatially organized. Thus, auditory spatial information is available exclusively
through central processing of binaural signals. Asymmetric hearing loss (AHL), which is one of the most
common forms of hearing impairment, profoundly disrupts spatial hearing and related functions such as
differentiating spatially-separated signals in noise (SIN). Remarkably, disabilities across hearing domains are
generally more severe in AHL patients than in equivalent cases of symmetric hearing loss (SHL), and more
severe than predicted by peripheral dysfunction. These disabilities are further compounded by problematic
downstream outcomes including tinnitus, cognitive impairment, and reduced quality of life. Increasing
recognition of the severe disabilities associated AHL has generated interest in a thorough understanding of its
central consequences, especially reorganization at the level of primary auditory cortex (ACtx). Binaural cortical
plasticity is traditionally assessed by shifts in characteristic frequency (CF) estimates obtained from the
hemisphere contralateral to the impaired ear. In general, CFs obtained from the impaired ear shift toward
frequencies of surviving cochlear cells. Although previous research has focused on shifts in spectral
processing, evaluation of changes in alternative response characteristics are needed to understand the neural
basis of the profound deficits in processing speech and SIN observed in AHL patients. Moreover, although
difficulties understanding SIN, such as speech in noisy environments, constitutes the largest clinical challenge
in AHL, no previous studies have directly investigated SIN processing in the central auditory pathway, or in
controlled animal behavioral experiments. The knowledge obtained in such preparations could generate novel
insights into the mechanisms underlying this debilitating condition and greatly facilitate the development of new
clinical interventions. With these goals in mind, we propose to conduct a multifaceted analysis of altered SIN
processing and cortical receptive field alteration following AHL using a transgenic mouse model. We will
augment classic pure-tone response metrics such as CF and threshold with spectrotemporal receptive field
(STRF) parameters including excitation-inhibition (E-I) ratio and temporal processing capabilities, which are
critical for perception of speech and SIN. We will further provide a detailed description of disrupted cortical SIN
processing in AHL by presenting elements of vocal communication signals in a range of competing background
noise levels. We will compare these outcomes to behavioral deficits in SIN processing in mice performing an
auditory discrimination task. The wealth of new insights made possible by this approach are capable of
resolving numerous outstanding questions regarding central reorgani...

## Key facts

- **NIH application ID:** 10063506
- **Project number:** 5F32DC016846-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** James Bigelow
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $72,630
- **Award type:** 5
- **Project period:** 2018-12-01 → 2021-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10063506

## Citation

> US National Institutes of Health, RePORTER application 10063506, Cortical reorganization and signal-in-noise processing following asymmetric hearing loss (5F32DC016846-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10063506. Licensed CC0.

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