# Molecular and Physiological Diversity of MSO Neurons and the Influence of Auditory Experience

> **NIH NIH F31** · UNIVERSITY OF TEXAS AT AUSTIN · 2020 · $39,720

## Abstract

Project Summary
 The Medial Superior Olive (MSO) is a mammalian brainstem nucleus that computes cues used for
azimuthal sound localization (interaural time differences, ITDs). Functionally, sound localization has been
theorized to be a necessary component not just for the simple acquisition of spatial information, but also for
higher order processing, such as language acquisition. 13% of people in the United States have some degree
of hearing loss in both ears1, but we do not fully understand how these deficits impact the ability to perform
basic computations, such as bilateral integration. Therefore, this work seeks to address specifically how
models of hearing loss may impact neural diversity.
 Based on recent findings in our lab, the MSO contains a previously undescribed diverse population of
repetitive firing neurons that are morphologically indistinguishable from phasic neuron counterparts, but
respond to similar inputs. The membrane and response properties of these neurons are consistent with the
time course of slower components of sounds, such as envelopes. This evidence suggests that the diversity of
MSO response patterns may reflect the ability of the nucleus to encode a broader array of sound features than
previously thought. Within this context, we question whether situations of hearing loss may restrict diversity of
response properties, and thus irreparably effect the ability of mammals to respond to both fast and slow spatial
cues. To test this hypothesize, we plan to use a combination of electrophysiology and immunohistochemistry to
measure response patterns of MSO neurons in a conductive hearing loss model and a model of decorrelated
information, lacking spatial cues. We predict that if repetitive firing neurons of the MSO are not present in the
two experimental models, then normally patterned auditory stimuli are likely necessary for the development of
these response types.
 Secondly, we hypothesize that the diversity of response types stems from a mechanistic alteration of
spike generation in MSO neurons. We predict that in models of hearing loss, auditory features will no longer
fine-tune the expression of voltage-gated sodium channels to generate a diverse set of responses. We will test
this by using antibody labeling for specific subunits of sodium channels and pulling nucleated patches to isolate
and measure somatic sodium currents. Together, these results will push our understanding of how hearing loss
affects diverse populations of neurons, while adding to our much-needed understanding of how intrinsic neuron
properties are shaped by auditory activity.

## Key facts

- **NIH application ID:** 10006123
- **Project number:** 5F31DC017377-03
- **Recipient organization:** UNIVERSITY OF TEXAS AT AUSTIN
- **Principal Investigator:** David B Haimes
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $39,720
- **Award type:** 5
- **Project period:** 2018-09-01 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10006123

## Citation

> US National Institutes of Health, RePORTER application 10006123, Molecular and Physiological Diversity of MSO Neurons and the Influence of Auditory Experience (5F31DC017377-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10006123. Licensed CC0.

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