Top-Down Influences of the Medial Olivocochlear Efferent System in Speech Perception in Noise

Mishra, Samarth; Lutman, Mark E.

doi:10.1371/journal.pone.0085756

Cited by 70 publications

(98 citation statements)

References 45 publications

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“…The simulations demonstrated that the amount of this gain inhibition is frequency-dependent with a maximal effect (at the range of 8 to 11 dB) for frquencies between 1 and 3.5 kHz. This was shown to reasonablly agree with the experimental data recorded from guinea pig, cat and human cochleae [1,5,7] where the MOC efferents had been externally elicited by broad-band stimuli.…”

Section: Resultssupporting

confidence: 81%

“…OAEs are produced in the inner-ear and their level is an important physiological indicator of the underlying OHC gain properties of the cochlea [4]. Their results [7] demonstrated an average 17.21% decrease in the CEOAE level due to the contralateral activation of the MOC efferents, which is comparable with the simulation results here ( Fig. 2A) showing a 19% gain reduction in the middle of the cochlea.…”

Section: Comparison With Experimental and Clinical Datasupporting

confidence: 88%

“…Furthermore, Mishra and Lutman [7] stimulated the MOC efferents in 18 normal hearing young humans using 30-dB SL contralateral broad band noise (0.125-12 kHz) and recorded the Click-Evoked OtoAcoustic Emissions (CEOAEs) simultaneously. OAEs are produced in the inner-ear and their level is an important physiological indicator of the underlying OHC gain properties of the cochlea [4].…”

Section: Comparison With Experimental and Clinical Datamentioning

confidence: 99%

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How do the medial olivocochlear efferents influence the biomechanics of the outer hair cells and thereby the cochlear amplifier? Simulation results

Saremi¹,

Stenfelt²,

Verhulst³

2015

AIP Conference Proceedings

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Abstract. The bottom-up signal pathway, which starts from the outer ear and leads to the brain cortices, gives the classic image of the human sound perception. However, there have been growing evidences in the last six decades for existence of a functional descending network whereby the central auditory system can modulate the early auditory processing, in a top-down manner. The medial olivocochlear efferent fibers project from the superior olivary complex at the brainstem into the inner ear. They are linked to the basal poles of the hair cells by forming synaptic cisterns. This descending network can activate nicotinic cholinergic receptors (nAChR) that increase the membrane conductance of the outer hair cells and thereby modify the magnitude of the active force generated inside the cochlea. The aim of the presented work is to quantitatively investigate how the changes in the biomechanics of the outer hair cells, caused by the efferent activation, manipulate the cochlear responses. This is done by means of a frequency-domain biophysical model of the cochlea [12] where the parameters of the model convey physiological interpretations of the human cochlear structures. The simulations manifest that a doubling of the outer hair cell conductance, due to efferent activation, leads to a frequency-dependent gain reduction along the cochlear duct with its highest effect at frequencies between 1 kHz and 3.5 kHz and a maximum of approximately 10 dB gain reduction at 2 kHz. This amount of the gain inhibition and its frequency dependence reasonably agrees with the experimental data recorded from guinea pig, cat and human cochleae where the medial olivococlear efferents had been elicited by broad-band stimuli. The simulations also indicate that the efferent-induced increase of the outer hair cell conductance increases the best frequency of the cochlear responses, in the basal region. The presented simulations quantitatively confirm that activation of the medial olivocochlear efferents can biomechanically manipulate the cochlear responses, in a top-down manner, by inhibiting the gain of the cochlear amplifier as well as altering the frequency-position map (tuning pattern) of the cochlea.

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Section: Resultssupporting

confidence: 81%

Section: Comparison With Experimental and Clinical Datasupporting

confidence: 88%

Section: Comparison With Experimental and Clinical Datamentioning

confidence: 99%

See 1 more Smart Citation

How do the medial olivocochlear efferents influence the biomechanics of the outer hair cells and thereby the cochlear amplifier? Simulation results

Saremi¹,

Stenfelt²,

Verhulst³

2015

AIP Conference Proceedings

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“…MOC feedback to the cochlea is believed to play roles in deciphering signals such as speech in noisy environments and protecting the cochlea from traumatizing exposures to sound (Liberman et al 2014;Mishra and Lutman 2014). Anomalous MOC function has been hypothesized, and tested for, in a variety of clinical conditions, including tinnitus, a prevalent and often disruptive condition in which sound is perceived in the absence of actual sound (Shargorodsky et al 2010;Stouffer and Tyler 1990).…”

mentioning

confidence: 99%

“…A widely used test of MOC function was employed that measures the effect of sound to one ear on the otoacoustic emissions (OAE) produced by outer hairs cells of the opposite ear (Hood et al 1996;Veuillet et al 1991). When measured in normal human subjects using common protocols, the effect is generally suppressive; that is, the magnitude of the OAE, for instance, distortion-product OAE (DPOAE), is reduced by contralaterally presented sound (commonly broadband noise; Hood et al 1996;Moulin et al 1993). In this study, DPOAE suppression was found in all subject groups, but it was greater in the groups with tinnitus and/or low SLT, indicating increased responsiveness of the MOC system.…”

mentioning

confidence: 99%

Increased contralateral suppression of otoacoustic emissions indicates a hyperresponsive medial olivocochlear system in humans with tinnitus and hyperacusis

Knudson

Shera

Melcher

2014

Journal of Neurophysiology

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Knudson IM, Shera CA, Melcher JR. Increased contralateral suppression of otoacoustic emissions indicates a hyperresponsive medial olivocochlear system in humans with tinnitus and hyperacusis. J Neurophysiol 112: 3197-3208, 2014. First published September 17, 2014 doi:10.1152/jn.00576.2014.-Atypical medial olivocochlear (MOC) feedback from brain stem to cochlea has been proposed to play a role in tinnitus, but even well-constructed tests of this idea have yielded inconsistent results. In the present study, it was hypothesized that low sound tolerance (mild to moderate hyperacusis), which can accompany tinnitus or occur on its own, might contribute to the inconsistency. Sound-level tolerance (SLT) was assessed in subjects (all men) with clinically normal or near-normal thresholds to form threshold-, age-, and sex-matched groups: 1) no tinnitus/high SLT, 2) no tinnitus/low SLT, 3) tinnitus/high SLT, and 4) tinnitus/low SLT. MOC function was measured from the ear canal as the change in magnitude of distortion-product otoacoustic emissions (DPOAE) elicited by broadband noise presented to the contralateral ear. The noise reduced DPOAE magnitude in all groups ("contralateral suppression"), but significantly more reduction occurred in groups with tinnitus and/or low SLT, indicating hyperresponsiveness of the MOC system compared with the group with no tinnitus/high SLT. The results suggest hyperresponsiveness of the interneurons of the MOC system residing in the cochlear nucleus and/or MOC neurons themselves. The present data, combined with previous human and animal data, indicate that neural pathways involving every major division of the cochlear nucleus manifest hyperactivity and/or hyperresponsiveness in tinnitus and/or low SLT. The overactivation may develop in each pathway separately. However, a more parsimonious hypothesis is that top-down neuromodulation is the driving force behind ubiquitous overactivation of the auditory brain stem and may correspond to attentional spotlighting on the auditory domain in tinnitus and hyperacusis.

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Projections from the ventral nucleus of the lateral lemniscus to the cochlea in the mouse

Suthakar

Ryugo

2021

J of Comparative Neurology

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Auditory efferents originate in the central auditory system and project to the cochlea. Although the specific anatomy of the olivocochlear (OC) efferents can vary between species, two types of auditory efferents have been identified based upon the general location of their cell bodies and their distinctly different axon terminations in the organ of Corti. In the mouse, the relatively small somata of the lateral (LOC) efferents reside in the lateral superior olive (LSO), have unmyelinated axons, and terminate around ipsilateral inner hair cells (IHCs), primarily against the afferent processes of type I auditory nerve fibers. In contrast, the larger somata of the medial (MOC) efferents are distributed in the ventral nucleus of the trapezoid body (VNTB), have myelinated axons, and terminate bilaterally against the base of multiple outer hair cells (OHCs). Using in vivo retrograde cell body marking, anterograde axon tracing, immunohistochemistry, and electron microscopy, we have identified a group of efferent neurons in mouse, whose cell bodies reside in the ventral nucleus of the lateral lemniscus (VNLL). By virtue of their location, we call them dorsal efferent (DE) neurons. Labeled DE cells were immuno-negative for tyrosine hydroxylase, glycine, and GABA, but immuno-positive for choline acetyltransferase.Morphologically, DEs resembled LOC efferents by their small somata, unmyelinated axons, and ipsilateral projection to IHCs. These three classes of efferent neurons all project axons directly to the cochlea and exhibit cholinergic staining characteristics.The challenge is to discover the contributions of this new population of neurons to auditory efferent function.

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Top-Down Influences of the Medial Olivocochlear Efferent System in Speech Perception in Noise

Cited by 70 publications

References 45 publications

How do the medial olivocochlear efferents influence the biomechanics of the outer hair cells and thereby the cochlear amplifier? Simulation results

How do the medial olivocochlear efferents influence the biomechanics of the outer hair cells and thereby the cochlear amplifier? Simulation results

Increased contralateral suppression of otoacoustic emissions indicates a hyperresponsive medial olivocochlear system in humans with tinnitus and hyperacusis

Projections from the ventral nucleus of the lateral lemniscus to the cochlea in the mouse

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