Cochlear hair cells: The sound‐sensing machines

Goutman, Juan D.; Elgoyhen, Ana Belén; Gómez-Casati, María Eugenia

doi:10.1016/j.febslet.2015.08.030

Cited by 89 publications

(66 citation statements)

References 130 publications

(185 reference statements)

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“…Feedback to the outer hair cells from efferent fibers originating in the medial olivocochlear nucleus could constitute a homeostatic mechanism similar to those that we describe (41). Stimulation of efferents innervating outer hair cells alters the cochlea's mechanical response to acoustic stimulation, diminishing both sensitivity and dynamic range (40,42).…”

Section: Discussionmentioning

confidence: 64%

“…Two types of hair cells are present within the mammalian cochlea: Inner hair cells provide input to the brain, whereas outer hair cells amplify the vibrational response of the cochlea (40,41). Feedback to the outer hair cells from efferent fibers originating in the medial olivocochlear nucleus could constitute a homeostatic mechanism similar to those that we describe (41).…”

Section: Discussionmentioning

confidence: 70%

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Homeostatic enhancement of sensory transduction

Milewski

Maoiléidigh

Salvi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Our sense of hearing boasts exquisite sensitivity, precise frequency discrimination, and a broad dynamic range. Experiments and modeling imply, however, that the auditory system achieves this performance for only a narrow range of parameter values. Small changes in these values could compromise hair cells' ability to detect stimuli. We propose that, rather than exerting tight control over parameters, the auditory system uses a homeostatic mechanism that increases the robustness of its operation to variation in parameter values. To slowly adjust the response to sinusoidal stimulation, the homeostatic mechanism feeds back a rectified version of the hair bundle's displacement to its adaptation process. When homeostasis is enforced, the range of parameter values for which the sensitivity, tuning sharpness, and dynamic range exceed specified thresholds can increase by more than an order of magnitude. Signatures in the hair cell's behavior provide a means to determine through experiment whether such a mechanism operates in the auditory system. Robustness of function through homeostasis may be ensured in any system through mechanisms similar to those that we describe here.hair cell | hearing | nonlinear dynamics | oscillation | robustness B iological systems are subject to developmental variation and environmental fluctuations. Homeostatic mechanisms nonetheless ensure that most individuals function well under a variety of conditions. For example, homeotherms maintain an internal body temperature within a few degrees of a set point thanks to mechanisms such as sweating, panting, shivering, and redirecting blood flow. Many organisms regulate blood pressure by changing blood-vessel diameter or by adjusting heart rate or stroke volume. How homeostasis occurs remains an open question in many contexts, particularly when the system in question operates near a transition between two distinct behaviors, as has been suggested in gene expression, neuronal networks, and flocking (1-4). Here, we seek the general principles underlying homeostatic mechanisms by studying a specific system whose high level of performance derives from operating near a dynamical transition. We propose a strategy that increases the robustness of sensory transduction to parameter variation.Within the range of human hearing, a trained ear can distinguish tones that differ in frequency by only 0.1% (5). The softest sounds that we can detect carry energies of the same magnitude as thermal fluctuations (6-9). We can, however, process sounds that convey a trillionfold more power (10). To achieve these specifications, the auditory system uses a set of active elements poised on the brink of self-oscillation (11). The presence of these self-oscillatory elements is evidenced by measurable sounds, termed spontaneous otoacoustic emissions, generated by our ears (8). It is unclear, however, how the auditory system maintains proximity to the boundary of spontaneous oscillation.Within the cochlea, hair cells transduce sound-induced vibrations into electrical signals, w...

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 70%

Homeostatic enhancement of sensory transduction

Milewski

Maoiléidigh

Salvi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…The organ of Corti is located in the cochlea of the inner ear and is responsible for the detection of sound. This organ harbours the auditory sensory epithelium, which, in humans, contains approximately 16,000 hair cells that are patterned into three rows of outer hair cells (OHCs) and one row of inner hair cells (IHCs) [1,2]. Each hair cell contains, at its apical surface, a mechanically sensitive organelle that consists of rows of actin-filled stereocilia that increasein height.…”

Section: Cochlea and Hair Cellsmentioning

confidence: 99%

The role of mitochondrial oxidative stress in hearing loss

González-González¹

2017

Neurol Disord Therap

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Hearing loss is the most common form of sensory impairment in humans, affecting 5.3% worldwide population. Although approximately 1 in 500 children are born with impaired hearing, sudden or progressive forms of hearing loss can manifest at any age. Hearing impairment following cochlear damage due to noise trauma, ototoxicity or age-related cochlear degeneration was linked to a common pathogenesis involving the formation of reactive oxygen species (ROS). This review summarizes the current data suggesting a role of mitochondrial ROS overproduction in hearing loss and the molecular mechanism involved in hair cell apoptosis responsible of this disorder. Because increasing number of studies demonstrated that antioxidants and free radical scavengers may serve as effective compounds to block the activation of cochlear hair cell death, targeting members of antioxidant pathways and in the breakdown of superoxide anions and hydrogen peroxidase, could be feasible options for the treatment of several types of hearing loss.Correspondence to: Sergio Gonzalez-Gonzalez, CILcare, 2214, Boulevard de la Lironde. Parc Scientifique Agropolis, Montpellier, France, E-mail: sergio. gonzalez@cilcare.com Cochlea and hair cellsThe mammalian cochlea is the sensory organ capable of perceiving sound over a range of pressure, and discriminating both infrasonic and ultrasonic frequencies in different species. The organ of Corti is located in the cochlea of the inner ear and is responsible for the detection of sound. This organ harbours the auditory sensory epithelium, which, in humans, contains approximately 16,000 hair cells that are patterned into three rows of outer hair cells (OHCs) and one row of inner hair cells (IHCs) [1,2]. Each hair cell contains, at its apical surface, a mechanically sensitive organelle that consists of rows of actin-filled stereocilia that increasein height. An extracellular matrix, the tectorial membrane, covers the apical surface of the organ of Corti and is attached to the hair bundles of OHCs. The cell bodies of hair cells form specialized adhesive contacts with supporting cells that adhere at their basolateral surfaces to the basilar membrane, an extracellular matrix assembly with a different molecular composition from the tectorial membrane [3,4].Hearing is initiated when sound waves that reach the outer ear travel through the ear canal to the tympanic membrane. Then, the sound energy is transferred, via the bony ossicles of the middle ear, to the oval window at the base of the fluid-filled cochlea. The motions of the oval window are converted into fluid pressure waves that induce vibrations in the basilar membrane. Then, the vibrations are transferred onto the hair cells, leading to the deflection of the hair cell stereocilia [5]. This deflection causes stretch-sensitive ion channels to open. These are non-selectively permeable to cations and are located at the base of the tip links, with 1 or 2 channels per tip link. Stereocilia bathe in endolymph, which is rich in potassium and characterized by an ...

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“…Inner hair cells detect and transmit auditory information, converting "graded depolarization into trains of action potentials in auditory nerve fibers", while outer hair cells are responsible for inner ear sensitivity and fine tuning [47].…”

Section: Lateral Inhibition In Auditionmentioning

confidence: 99%

“…The inner and outer hair cells of the ears: 1) facilitate transduction of sound waves; 2) are controlled by "efferent inhibitory innervations"; and 3) are responsible for correlating cell length with membrane potential changes [47].…”

Section: Lateral Inhibition In Auditionmentioning

confidence: 99%

Sensory Consciousness is Experienced through Amplification of Sensory Stimuli via Lateral Inhibition

Jerath¹,

Cearley²,

Paladiya³

et al. 2017

WJNS

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At present, researchers are unclear about which activity within the brain is responsible for the emergence of consciousness-the subconscious or unconscious. Current literature suggests that consciousness is isolated in the brain; however, we suggest consciousness emerges from both-subconscious and unconscious activity, in addition to sensory consciousness. This article contends that sensory consciousness arises from neurophysiological brain activity, intrapersonal space, sensory information, and parallel processing of the external and internal environment through vision, olfaction, the integumentary system, gustation, and audition. Traditionally, lateral inhibition is defined as the ability for an excited neuron to laterally inhibit its neighbors, and is an integral part of neurophysiology in all senses. In this article, we are connecting the science behind the well-established physiological observations of gamma wave activity in the interneurons of peripheral receptors with what is currently unknown regarding the functional significance of seemingly unrelated gamma activity in the cortico-thalamic gamma oscillations. We suggest that this allows for instantaneous integration of the brain with sensory receptors. This article uses existing literature on lateral inhibition to investigate its role in sensory organs and various areas of the body. We explain how sensory consciousness is only one component of unified consciousness. We propose that lateral inhibition also plays a vital role in consciousness theory, and understanding this can help illustrate the dynamic interactions between the central and peripheral nervous systems within the body.

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Cochlear hair cells: The sound‐sensing machines

Cited by 89 publications

References 130 publications

Homeostatic enhancement of sensory transduction

Homeostatic enhancement of sensory transduction

The role of mitochondrial oxidative stress in hearing loss

Sensory Consciousness is Experienced through Amplification of Sensory Stimuli via Lateral Inhibition

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