scholarly journals Static length changes of cochlear outer hair cells can tune low-frequency hearing

2018 ◽  
Vol 14 (1) ◽  
pp. e1005936 ◽  
Author(s):  
Nikola Ciganović ◽  
Rebecca L. Warren ◽  
Batu Keçeli ◽  
Stefan Jacob ◽  
Anders Fridberger ◽  
...  
Keyword(s):  
Hair Cells ◽  
Low Frequency ◽  
Outer Hair Cells ◽  
Length Changes

scholarly journals Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haim Sohmer
Keyword(s):  
Soft Tissue ◽  
Hair Cells ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Frequency Discrimination ◽  
Outer Hair Cells ◽  
Common Mechanism ◽  
Frequency Stimulation

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

The location and mechanism of electromotility in guinea pig outer hair cells

1993 ◽  
Vol 70 (2) ◽  
pp. 549-558 ◽  
Author(s):  
R. Hallworth ◽  
B. N. Evans ◽  
P. Dallos
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Length Change ◽  
Opposite Polarity ◽  
Outer Hair Cells ◽  
Response Amplitude ◽  
Change Function ◽  
Length Changes ◽  
Diameter Change

1. The microchamber method was used to examine the motile responses of isolated guinea pig outer hair cells to electrical stimulation. In the microchamber method, an isolated cell is drawn partway into a suction pipette and stimulated transcellularly. The relative position of the cell in the microchamber is referred to as the exclusion fraction. 2. The length changes of the included and excluded segments were compared for constant sinusoidal stimulus amplitude as functions of the exclusion fraction. Both included and excluded segments showed maximal responses when the cell was excluded approximately halfway. Both segments showed smaller or absent responses when the cell was almost fully excluded or almost fully included. 3. When the cell was near to, but not at, the maximum exclusion, the included segment response amplitude was zero, whereas the excluded segment response amplitude was nonzero. In contrast, when the cell was nearly fully included, the excluded segment response amplitude was zero, but the included segment response amplitude was still detectable. A simple model of outer hair cell motility based on these results suggests that the cell has finite-resistance terminations and that the motors are restricted to a region above the nucleus and below its ciliated apex (cuticular plate). 4. The function describing length change as a function of command voltage was measured for each segment as the exclusion fraction was varied. The functions were similar at midrange exclusions (i.e., when the segments were about equal length), showing nonlinearity and saturability. The functions were strikingly different when the segment lengths were different. The effects of exclusion on the voltage to length-change functions suggested that the nonlinearity and saturability are local properties of the motility mechanism. 5. The diameter changes of both segments were examined. The segment diameter changes were always antiphasic to the length changes. This finding implies that the motility mechanism has an active antiphasic diameter component. The diameter change amplitude was a monotonically increasing function of exclusion for the included segment, and a decreasing function for the excluded segment. 6. The voltage to length-change and voltage to diameter-change functions were measured for the same cell and exclusion fraction. The voltage to diameter-change function was smaller in amplitude than the voltage to length-change function. The functions were of opposite polarity to each other, but were otherwise similar in character. Thus it is likely that the same motor mechanism is responsible for both axial and diameter deformations.

Electrically Evoked Motile Responses of Mammalian Type I Vestibular Hair Cells

1992 ◽  
Vol 2 (3) ◽  
pp. 181-191
Author(s):  
Hans Peter Zenner ◽  
Günter Reuter ◽  
Shi Hong ◽  
Ulrike Zimmermann ◽  
Alfred H. Gitter
Keyword(s):  
Hair Cells ◽  
Sensory Modality ◽  
Outer Hair Cells ◽  
Type I ◽  
Image Subtraction ◽  
Low Frequencies ◽  
Vestibular Hair Cells ◽  
Mechanical Responses ◽  
Contrast Enhanced ◽  
Length Changes

Vestibular hair cells, type I and II, with membrane potentials around -64 mV were prepared from guinea pig ampullar cristae and maculae. In type I cells, current injection, application of voltage steps during membrane patch-clamping, or extracellular alternating current (ac) fields evoked fast length changes of 50 nm to 500 nm of the cell “neck”. Mechanical responses were determined by computerized video techniques with contrast-enhanced digital image subtraction (DIS) and interpeak pixel counts (IPPC) or by double photodiode measurements. These techniques allowed spatial resolutions of 300 nm, 120 nm, and 50 nm, respectively. In contrast to measurements of high-frequency movements of auditory outer hair cells (OHCs), the mechanical responses of type I VHCs were restricted to low frequencies below 85 Hz. In addition to recently reported slow motility of VHCs, the present results suggest that fast mechanical VHC responses could significantly influence macular and cupular mechanics. Isometric and isotonic variants are discussed. The observed frequency maxima gap between VHCs and OHCs is suggested to contribute to a clear separation of the auditory and the vestibular sensory modality.

scholarly journals The ultrastructural distribution of prestin in outer hair cells: a post-embedding immunogold investigation of low-frequency and high-frequency regions of the rat cochlea

2010 ◽  
Vol 31 (9) ◽  
pp. 1595-1605 ◽  
Author(s):  
Shanthini Mahendrasingam ◽  
Maryline Beurg ◽  
Robert Fettiplace ◽  
Carole M. Hackney
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Low Frequency ◽  
Outer Hair Cells ◽  
Rat Cochlea

scholarly journals Forces involved in length changes of cochlear outer hair cells

1993 ◽  
Vol 425 (1-2) ◽  
pp. 190-190
Author(s):  
Alfred H. Gitter ◽  
Maximilian Rudert ◽  
Hans -Peter Zenner
Keyword(s):  
Hair Cells ◽  
Outer Hair Cells ◽  
Length Changes

Mechanically induced length changes of isolated outer hair cells are metabolically dependent

1991 ◽  
Vol 53 (1) ◽  
pp. 7-16 ◽  
Author(s):  
Barbara Canlon ◽  
Lou Brundin
Keyword(s):  
Hair Cells ◽  
Outer Hair Cells ◽  
Length Changes

Prestin Expression in Cochlea of Bats Using Different Echolocation Systems

2014 ◽  
Vol 620 ◽  
pp. 248-252
Author(s):  
Qi Jiu Li ◽  
Xian De Zhang ◽  
Ting Ting Xu ◽  
Jiang Xia Yin
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Low Frequency ◽  
Motor Protein ◽  
Outer Hair Cells ◽  
Intracellular Potential ◽  
First Time ◽  
Unique Ability

Outer hair cells (OHCs) have a unique ability to contract and elongate in response to changes in intracellular potential, and Prestin is the motor protein of the cochlea of the OHCs. It is the first time to invest the Prestin expression in different bat species. To invest Prestin expression in different bat species, which have different frequency, we did the coronal sections’ staining of the cochlea using immunhistochemistry. Experiment was designed to determine if the high-frequency bats’ OHCs have more expression than the low-frequency bats’OHCs. We found that the expression in three species was similar and had no obvious difference. Though the study of bats Prestin evolution suggested that Prestin has accelerating evolution in echolocation bats with high frequency, our we showed that the Prestin expression has nothing to do with the frequency, and the Prestin expression in high-frequency bats and low-frequency bats is similar.

scholarly journals Static length changes of cochlear outer hair cells can tune low-frequency hearing

2017 ◽  
Author(s):  
Nikola Ciganović ◽  
Rebecca L. Warren ◽  
Batu Keçeli ◽  
Stefan Jacob ◽  
Anders Fridberger ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Frequency Selectivity ◽  
Apical Region ◽  
Low Frequencies ◽  
Inner Hair Cells ◽  
Length Changes ◽  
The Brain

AbstractThe cochlea not only transduces sound-induced vibration into neural spikes, it also amplifies weak sound to boost its detection. Actuators of this active process are sensory outer hair cells in the organ of Corti, whereas the inner hair cells transduce the resulting motion into electric signals that propagate via the auditory nerve to the brain. However, how the outer hair cells modulate the stimulus to the inner hair cells remains unclear. Here, we combine theoretical modeling and experimental measurements near the cochlear apex to study the way in which length changes of the outer hair cells deform the organ of Corti. We develop a geometry-based kinematic model of the apical organ of Corti that reproduces salient, yet counter-intuitive features of the organ’s motion. Our analysis further uncovers a mechanism by which a static length change of the outer hair cells can sensitively tune the signal transmitted to the sensory inner hair cells. When the outer hair cells are in an elongated state, stimulation of inner hair cells is largely inhibited, whereas outer hair cell contraction leads to a substantial enhancement of sound-evoked motion near the hair bundles. This novel mechanism for regulating the sensitivity of the hearing organ applies to the low frequencies that are most important for the perception of speech and music. We suggest that the proposed mechanism might underlie frequency discrimination at low auditory frequencies, as well as our ability to selectively attend auditory signals in noisy surroundings.Author summaryOuter hair cells are highly specialized force producers inside the inner ear: they can change length when stimulated electrically. However, how exactly this electromotile effect contributes to the astonishing sensitivity and frequency selectivity of the inner ear has remained unclear. Here we show for the first time that static length changes of outer hair cells can sensitively regulate how much of a sound signal is passed on to the inner hair cells that forward the signal to the brain. Our analysis holds for the apical region of the inner ear that is responsible for detecting the low frequencies that matter most in speech and music. This shows a mechanisms for how frequency-selectivity can be achieved at low frequencies. It also opens a path for the efferent neural system to regulate hearing sensitivity.

scholarly journals PIEZO2 mediates ultrasonic hearing via cochlear outer hair cells in mice

2021 ◽  
Vol 118 (28) ◽  
pp. e2101207118
Author(s):  
Jie Li ◽  
Shuang Liu ◽  
Chenmeng Song ◽  
Qun Hu ◽  
Zhikai Zhao ◽  
...  
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Social Communication ◽  
Ex Vivo ◽  
Low Frequency ◽  
Outer Hair Cells ◽  
Freezing Behavior ◽  
Physiological Mechanisms ◽  
Effector Cells ◽  
Mechanosensitive Ion Channel

Ultrasonic hearing and vocalization are the physiological mechanisms controlling echolocation used in hunting and navigation by microbats and bottleneck dolphins and for social communication by mice and rats. The molecular and cellular basis for ultrasonic hearing is as yet unknown. Here, we show that knockout of the mechanosensitive ion channel PIEZO2 in cochlea disrupts ultrasonic- but not low-frequency hearing in mice, as shown by audiometry and acoustically associative freezing behavior. Deletion of Piezo2 in outer hair cells (OHCs) specifically abolishes associative learning in mice during hearing exposure at ultrasonic frequencies. Ex vivo cochlear Ca2+ imaging has revealed that ultrasonic transduction requires both PIEZO2 and the hair-cell mechanotransduction channel. The present study demonstrates that OHCs serve as effector cells, combining with PIEZO2 as an essential molecule for ultrasonic hearing in mice.

scholarly journals An unusually powerful mode of low-frequency sound interference due to defective hair bundles of the auditory outer hair cells

2014 ◽  
Vol 111 (25) ◽  
pp. 9307-9312 ◽  
Author(s):  
K. Kamiya ◽  
V. Michel ◽  
F. Giraudet ◽  
B. Riederer ◽  
I. Foucher ◽  
...  
Keyword(s):  
Hair Cells ◽  
Low Frequency ◽  
Outer Hair Cells ◽  
Frequency Sound ◽  
Hair Bundles
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