NIH Reporter #5R01DC019341-05

Development of Temporal Fine structure

This award funds research to understand sound localization and binaural hearing development using avian models, aiming to improve hearing aid and cochlear implant design by studying temporal fine structure and interaural time differences.

Description

The broad goal of the proposed research program is to advance our understanding of sound localization. Even when a person has normal hearing, speech perception and learning in noisy reverberant environments may still be compromised due to persistently impaired binaural hearing capabilities. In more profound cases of deafness, bilateral cochlear implant users typically experience poor discrimination of interaural time differences (ITDs), potentially because of early deprivation. This proposal uses an avian model to advance our understanding of binaural development. We have developed this preparation to determine if/when there is a developmental window in which inputs from each ear are synchronized, in order for sensitivity to ITDs to develop. Sensitivity to binaural signals first appears in the brainstem and relies on sub-millisecond precision to detect ITDs. How such extreme precision comes about during development is not fully understood, and these birds provide a well understood model for measurement of precisely timed binaural signals. Our knowledge of this ITD circuit is detailed enough to test hypotheses about the physiology and development of sound localization circuits. The project investigates three main areas: 1. Whether the representation of ITDs is plastic during development, using a unilateral conductive hearing loss model to induce experience-dependent plasticity. 2. Mechanisms underlying the emergence of temporal precision, by combining extracellular and intracellular recordings to measure ITD development. 3. The role of inhibition in the development of ITD coding, examining inhibitory input to relevant nuclei.

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