Language
English
Publication Date
4-9-2025
Journal
The Journal of Neuroscience
DOI
10.1523/JNEUROSCI.2103-24.2025
PMID
39984203
PMCID
PMC11984096
PubMedCentral® Posted Date
2-21-2025
PubMedCentral® Full Text Version
Post-print
Abstract
The mammalian cochlea receives efferent feedback from the brain. Many functions for this feedback have been hypothesized, including on short timescales, such as mediating attentional states, and long timescales, such as buffering acoustic trauma. Testing these hypotheses has been impeded by an inability to make direct measurements of efferent effects in awake animals. Here, we assessed the role of the medial olivocochlear (MOC) efferent nerve fibers on cochlear amplification by measuring organ of Corti vibratory responses to sound in both sexes of awake and anesthetized mice. We studied long-term effects by genetically ablating the efferents and/or afferents. Cochlear amplification increased with deafferentation using VGLUT3−/− mice, but only when the efferents were intact, associated with increased activity within OHCs and supporting cells. Removing both the afferents and the efferents using VGLUT3−/− Alpha9−/− mice did not cause this effect. To test for short-term effects, we recorded sound-evoked vibrations while using pupillometry to measure neuromodulatory brain state. We found no state dependence of cochlear amplification or of the auditory brainstem response. However, state dependence was apparent in the downstream inferior colliculus. Thus, MOC efferents upregulate cochlear amplification chronically with hearing loss, but not acutely with brain state fluctuations. This pathway may partially compensate for hearing loss while mediating associated symptoms, such as tinnitus and hyperacusis.
Keywords
Animals, Mice, Cochlea, Efferent Pathways, Male, Female, Olivary Nucleus, Hearing Loss, Mice, Knockout, Acoustic Stimulation, Mice, Inbred C57BL, Evoked Potentials, Auditory, Brain Stem, Amino Acid Transport Systems, Acidic, brain state, cochlea, feedback, hearing, optical coherence tomography, outer hair cell, pupillometry
Published Open-Access
yes
Recommended Citation
Quiñones, Patricia M; Pei, Michelle; Srivastava, Hemant; et al., "The Medial Olivocochlear Efferent Pathway Potentiates Cochlear Amplification in Response to Hearing Loss" (2025). Faculty and Staff Publications. 5298.
https://digitalcommons.library.tmc.edu/baylor_docs/5298