NIH grant: Brain Plasticity in aging adults with hearing loss (1R01DC022765-01A1)

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NIH grant 1R01DC022765-01A1: Brain Plasticity in aging adults with hearing loss
Institute: {'code': 'DC', 'abbreviation': 'NIDCD', 'name': 'National Institute on Deafness and Other Communication Disorders', 'admin_org_id': '12500019', 'admin_funding_url': ''}. PI: KELLY C HARRIS. Award: $624043.
Start: 2026-07-10T00:00:00.
PROJECT SUMMARY/ABSTRACT
Age-related hearing loss (HL) is one of the most common chronic conditions of aging, yet little is known about
how the aging brain adapts to this gradual loss of auditory input. Neural adaptation, or plasticity, can occur in
response to HL and may impact speech recognition and rehabilitation success. Neuroplastic mechanisms may
be more malleable to novel therapeutics than peripheral deficits opening new avenues for interventions. The
proposed projects target two aspects of neural plasticity, Gamma aminobutyric acid (GABA), the primary
inhibitory neurotransmitter in the brain, and adaptive myelination- or the activity-dependent degeneration and
enhancement of myelin that alters the thickness, abundance and function of myelin in the central nervous
system. These measures are key to plasticity and auditory function, can be measured non-invasively, allowing
for the objective identification of potential candidates for treatment, and the ability to quantify treatment
outcomes. Moreover, training, neuromodulation, and pharmaceuticals are already available to increase myelin
and modulate GABA. However, prior to intervention we must first understand the role that age and HL have on
these mechanisms, and how they potentially interact to effect auditory and audiovisual speech recognition. Aim
1 considers how lower levels of GABA that occurs with HL, previously shown by our laboratory to be
maladaptive to auditory speech in noise recognition (SIN), may contribute to increased cross-sensory plasticity
predisposing the aging brain to rely more on multimodal processing. GABA and adaptive myelination are both
activity-dependent and tightly coupled. The proposed experiments consider how increased reliance on visual
cues and multisensory integration may alter structural connections, by enhancing myelin along connections
between auditory and visual and multisensory brain regions and increasing cross-sensory encoding. HL may
also contribute to a degeneration in myelin in the auditory system. Sound processing is accomplished through
structural and functional specifications that allow the auditory system to process signals with microsecond
precision: a time scale that is amenable to adjustments in myelin. Aging and HL are known to contribute to
myelin degeneration, yet to date there have been no studies of myelin across the auditory system in older
adults. Experiments test the hypothesis that HL exaggerates age-related myelin degeneration in the auditory
system, contributing to decreased temporal resolution and poorer speech recognition. This comprehensive
series of experiments examines estimates of function from the ear through the cortex, estimates of GABA from
unimodal sensory and multimodal cortical regions, cortical encoding of auditory and visual stimuli, quantifies
myelin, and uses self-report questionnaires to assess how HL and plasticity translate to everyday listening. A
significant advancement in our understanding of changes in the aging brain resulting from peripheral deficits
and cortical plasticity is needed to identify potential biomarkers and potential candidates for intervention.

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