Spontaneous otoacoustic emissions in TectaY1870C/+ mice reflect changes in cochlear amplification and how it is controlled by the tectorial membrane

Cheatham, Mary Ann, Zhou, Yingje, Goodyear, Richard J, Dallos, Peter and Richardson, Guy (2018) Spontaneous otoacoustic emissions in TectaY1870C/+ mice reflect changes in cochlear amplification and how it is controlled by the tectorial membrane. eNeuro, 5 (6). ) e0314-18.2018 1-15. ISSN 2373-2822

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Abstract

Spontaneous otoacoustic emissions (SOAEs) recorded from the ear canal in the absence of sound reflect cochlear amplification, an outer-hair-cell (OHC) process required for the extraordinary sensitivity and frequency selectivity of mammalian hearing. Although wild-type mice rarely emit, those with mutations that influence the tectorial membrane (TM) show an incidence of SOAEs similar to that in humans. In this report, we characterized mice with a missense mutation in Tecta, a gene required for the formation of the striated-sheet matrix within the core of the TM. Mice heterozygous for the Y1870C mutation (TectaY1870C/+) are prolific emitters, despite a moderate hearing loss. Additionally, Kimura’s membrane, into which the OHC stereocilia insert, separates from the main body of the TM, except at apical cochlear locations. Multimodal SOAEs are also observed in TectaY1870C/+ mice where energy is present at frequencies that are integer multiples of a lower-frequency SOAE (the primary). Second-harmonic SOAEs, at twice the frequency of a lower-frequency primary, are the most frequently observed. These secondary SOAEs are found in spatial regions where stimulus-evoked OAEs are small or in the noise floor. Introduction of high-level suppressors just above the primary SOAE frequency reduce or eliminate both primary and second-harmonic SOAEs. In contrast, second-harmonic SOAEs are not affected by suppressors, either above or below the second-harmonic SOAE frequency, even when they are much larger in amplitude. Hence, second-harmonic SOAEs do not appear to be spatially separated from their primaries, a finding that has implications for cochlear mechanics and the consequences of changes to TM structure.

Item Type: Article
Schools and Departments: School of Life Sciences > Neuroscience
Research Centres and Groups: Sussex Neuroscience
Subjects: Q Science
Q Science > QP Physiology
Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology
Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology > QP0431 Senses
Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology > QP0431 Senses > QP0448 Special senses
Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology > QP0431 Senses > QP0448 Special senses > QP0461 Hearing. Physiological acoustics
Depositing User: Guy Richardson
Date Deposited: 01 Aug 2019 09:35
Last Modified: 01 Aug 2019 09:45
URI: http://sro.sussex.ac.uk/id/eprint/81004

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