Sound-induced length changes in outer hair cell stereocilia

Hakizimana, Pierre; Brownell, William E.; Jacob, Stefan; Fridberger, Anders

doi:10.1038/ncomms2100

Cited by 33 publications

(34 citation statements)

References 43 publications

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“…The smaller motion at the tip of the hair bundle also show that the outer hair cell stereocilia bundles change length on a cycle-by-cycle basis during sound stimulation, as previously reported [13]. Since motion in the XY plane suffices to describe many aspects of sound-evoked stereocilia motion, we restricted the remaining experiments to this plane, since the acquisition time is less than 1/20th of the one required for three-dimensional data sets.…”

Section: Three-dimensional Hair Bundle Vibrationsmentioning

confidence: 75%

“…Oxygenated medium flowed continuously through the tubing at a speed of approximately 20 μl/min, the minimum rate consistent with stable flow. A second hole at the apex of the cochlea provided an outlet for the perfusion medium, allowed the organ of Corti to be visualized with water immersion optics (×40 lens, numerical aperture 0.8, Zeiss Gmbh, Göttingen, Germany) and provided access for borosilicate glass microelectrodes used for measuring cochlear microphonic potentials and for electrophoretic staining of the stereocilia [13]. The preparation was placed on the motorized stage of a laser scanning confocal microscope (LSM510, Zeiss).…”

Section: Methodsmentioning

confidence: 99%

“…Stimulus generation began when the board received the frame trigger from the microscope [8,13,16]. These procedures ensured that each pixel in a series of images was acquired at a known phase of the acoustic stimulus.…”

Section: Electrophysiologymentioning

confidence: 99%

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Effects of salicylate on sound-evoked outer hair cell stereocilia deflections

Hakizimana

Fridberger

2014

Pflugers Arch - Eur J Physiol

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Hearing depends on sound-evoked deflections of the stereocilia that protrude from the sensory hair cells in the inner ear. Although sound provides an important force driving stereocilia, forces generated through mechanically sensitive ion channels and through the motor protein prestin have been shown to influence stereocilia motion in solitary hair cells. While a possible influence of prestin on mechanically sensitive ion channels has not been systematically investigated, a decrease in transducer currents is evident in solitary hair cells when prestin is blocked with salicylate, raising the question of whether a reduced prestin activity or salicylate itself affected the mechanotransduction apparatus. We used two- and three-dimensional time-resolved confocal imaging to visualize outer hair cell stereocilia during sound stimulation in the apical turn of cochlear explant preparations from the guinea pig. Surprisingly, following application of salicylate, outer hair cell stereocilia deflections increased, while cochlear microphonic potentials decreased. However, when prestin activity was altered with the chloride ionophore tributyltin, both the cochlear microphonic potential and the stereocilia deflection amplitude decreased. Neither positive nor negative current stimulation abolished the bundle movements in the presence of salicylate, indicating that the observed effects did not depend on the endocochlear potential. These data suggest that salicylate may alter the mechanical properties of stereocilia, decreasing their bending stiffness.

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Section: Three-dimensional Hair Bundle Vibrationsmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 99%

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Effects of salicylate on sound-evoked outer hair cell stereocilia deflections

Hakizimana

Fridberger

2014

Pflugers Arch - Eur J Physiol

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“…Initial experiments were performed on isolated preparations of the guinea pig temporal bone (24,25). Sound stimulation occurred through the intact middle ear ossicles, and the resulting cellular movements of the organ of Corti (Fig.…”

Section: Resultsmentioning

confidence: 99%

Minimal basilar membrane motion in low-frequency hearing

Warren

Ramamoorthy

Ciganović

et al. 2016

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

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Low-frequency hearing is critically important for speech and music perception, but no mechanical measurements have previously been available from inner ears with intact low-frequency parts. These regions of the cochlea may function in ways different from the extensively studied high-frequency regions, where the sensory outer hair cells produce force that greatly increases the soundevoked vibrations of the basilar membrane. We used laser interferometry in vitro and optical coherence tomography in vivo to study the low-frequency part of the guinea pig cochlea, and found that sound stimulation caused motion of a minimal portion of the basilar membrane. Outside the region of peak movement, an exponential decline in motion amplitude occurred across the basilar membrane. The moving region had different dependence on stimulus frequency than the vibrations measured near the mechanosensitive stereocilia. This behavior differs substantially from the behavior found in the extensively studied high-frequency regions of the cochlea.hearing | basilar membrane | optical coherence tomography | hair cells S ound causes traveling waves to propagate within the fluids of the inner ear and along the basilar membrane, from the base of the cochlea toward its apex (1-4). These waves move the sensory hair cells, deflect their stereocilia, and lead to receptor potential generation and modulation of spike rates in the auditory nerve. Because of systematic variations in basilar membrane properties, high-frequency sound stimulates sensory cells near the base of the cochlear spiral, whereas the low sound frequencies that are most important for speech and music perception cause maximal stimulation of hair cells near the apex of the spiral.Importantly, the sensory outer hair cells of the organ of Corti are mechanically active: Their soma changes length upon electrical stimulation (5, 6), and their hair bundles can provide force (7-9). Recent theoretical and experimental work showed that forces produced by the outer hair cells feed back into the sound-evoked motion of the basilar membrane and amplify the fluid motion associated with the traveling wave (10-12). The amplitude of the traveling wave therefore grows successively as it moves forward, causing a 1,000-fold increase of sound-evoked basilar membrane motion at the place of maximum vibration (13)-at least in the high-frequency regions of the cochlea. The functionally important low-frequency parts of the inner ear appear to behave in a different manner, however.Specifically, a recent mathematical model suggested a "ratchet" behavior, where the sensory outer hair cells amplify sound-evoked motion close to stereocilia, but not at the basilar membrane (14). If the theory has merit, basilar membrane movements are expected to be quite small, to be uninfluenced by hair-cell force generation, and to peak at a frequency that is unrelated to the frequency at which the hair bundles vibrate with their largest amplitude, a behavior distinct from the behavior found in the high-frequency regions.Some expe...

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“…The spatially averaged fluorescence was fit with an exponential decay. The deviation away from the exponential provided ΔF, and the value on the exponential provided F. Custom software time-stamped each pixel with the latency relative to the most recent stimulus trigger (21). Image data were analyzed using 1-μm 2 regions of interest (areas).…”

Section: Methodsmentioning

confidence: 99%