Static material properties of the tectorial membrane: a summary

Freeman, Dennis M.; Masaki, Kinuko; McAllister, Abraham R.; Wei, Jesse; Weiß, Thomas

doi:10.1016/s0378-5955(03)00072-8

Cited by 46 publications

(47 citation statements)

References 99 publications

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“…In another set of experiments, Freeman et al (2003a;2003b) placed a section of mouse TM membrane in a cell-tack coated chamber and vibrated this chamber with a piezo actuator at frequencies between 10 and 14 kHz. At the same time, they recorded the mechanically induced vibrations of the TM with an atomic force cantilever with known mechanical impedance.…”

Section: Tectorial Membranementioning

confidence: 99%

Basilar Membrane and Tectorial Membrane Stiffness in the CBA/CaJ Mouse

Teudt

Richter

2014

JARO

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The mouse has become an important animal model in understanding cochlear function. Structures, such as the tectorial membrane or hair cells, have been changed by gene manipulation, and the resulting effect on cochlear function has been studied. To contrast those findings, physical properties of the basilar membrane (BM) and tectorial membrane (TM) in mice without gene mutation are of great importance. Using the hemicochlea of CBA/CaJ mice, we have demonstrated that tectorial membrane (TM) and basilar membrane (BM) revealed a stiffness gradient along the cochlea. While a simple spring mass resonator predicts the change in the characteristic frequency of the BM, the spring mass model does not predict the frequency change along the TM. Plateau stiffness values of the TM were 0.6±0.5, 0.2± 0.1, and 0.09±0.09 N/m for the basal, middle, and upper turns, respectively. The BM plateau stiffness values were 3.7±2.2, 1.2±1.2, and 0.5±0.5 N/m for the basal, middle, and upper turns, respectively. Estimations of the TM Young's modulus (in kPa) revealed 24.3±25.2 for the basal turns, 5.1±4.5 for the middle turns, and 1.9±1.6 for the apical turns. Young's modulus determined at the BM pectinate zone was 76.8±72, 23.9±30.6, and 9.4±6.2 kPa for the basal, middle, and apical turns, respectively. The reported stiffness values of the CBA/CaJ mouse TM and BM provide basic data for the physical properties of its organ of Corti.

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Section: Tectorial Membranementioning

confidence: 99%

Basilar Membrane and Tectorial Membrane Stiffness in the CBA/CaJ Mouse

Teudt

Richter

2014

JARO

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“…In addition, mechanical strain produces electrical responses [e.g., streaming potentials (35)], and electrical stimulation may lead to mechanical deformations by a process referred to as electrokinetics (39,40). The similarity between the structure and composition of the TM and those of other connective tissues suggests the possibility that charge might play a similarly important role in the function of the TM (27,28).In this study, we developed microfabricated devices that interface with the soft and fragile structure of fresh, excised TM segments to (i) measure the fixed charge density of the TM and (ii) apply oscillatory electric fields at audio frequencies to the TM. Using these methodologies, we demonstrate electrokinetic phenomena elicited by the presence of fixed charge and suggest implications for hearing mechanisms.…”

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confidence: 99%

“…These results are consistent with predictions based on biochemical composition studies (27). The net charge of approximately −7.1 mmol/L at physiological pH is large, representing 1 fixed charge molecule for every ∼25 cations in endolymph.To determine the mechanical contribution of charge in the TM, we analyzed a macrocontinuum model based on the stress-strain relation and Donnan equilibrium (27,41). Internal pressures that…”

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confidence: 99%

Electrokinetic properties of the mammalian tectorial membrane

Ghaffari

Page

Farrahi

et al. 2013

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

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The tectorial membrane (TM) clearly plays a mechanical role in stimulating cochlear sensory receptors, but the presence of fixed charge in TM constituents suggests that electromechanical properties also may be important. Here, we measure the fixed charge density of the TM and show that this density of fixed charge is sufficient to affect mechanical properties and to generate electrokinetic motions. In particular, alternating currents applied to the middle and marginal zones of isolated TM segments evoke motions at audio frequencies (1-1,000 Hz). Electrically evoked motions are nanometer scaled (∼5-900 nm), decrease with increasing stimulus frequency, and scale linearly over a broad range of electric field amplitudes (0.05-20 kV/m). These findings show that the mammalian TM is highly charged and suggest the importance of a unique TM electrokinetic mechanism.cochlear amplification | cochlear mechanics | mechanoelectrical transduction | motility T he mammalian cochlea is a remarkable sensor capable of detecting and analyzing sounds that generate subatomic vibrations (1). This extraordinary sensing property depends on mechanoelectrical transduction (MET) of cochlear hair cells (2, 3), which are functionally classified as inner and outer hair cells (OHCs). Both types of hair cells project stereociliary hair bundles from their apical surface toward an overlying extracellular matrix called the tectorial membrane (TM). Because of its strategic position above the hair bundles, the TM is believed to play a critical role in bundle deflection. Recently, genetic studies confirmed the importance of the TM in hair cell stimulation by highlighting how mutations of TM proteins cause severe hearing deficits, even when the TM and its structural attachments appear to be normal under electron microscopy (4-8).Despite significant evidence establishing the importance of the TM in normal cochlear function, relatively little is known about the TM's basic physicochemical properties and mechanistic role. Historically, models of cochlear function have represented the TM as a stiff lever with a compliant hinge, as a resonant mass-spring system, or as an inertial body (9-16). However, these models exclude important phenomena, such as longitudinal coupling (17)(18)(19)(20), and assume that only mechanical properties of the TM are important. It now is clear that the TM is a biphasic poroelastic tissue (21), which manifests longitudinal coupling in the form of traveling waves (18)(19)(20).Furthermore, TM macromolecules comprise not only mechanical constituents (21-26) such as collagen fibrils, but also charged constituents such as glycosaminoglycans (GAGs), which might affect mechanical properties (Fig. 1) (27-35). GAGs in the TM carry sulfate (SO 3 − ) and carboxyl (COO − ) charge groups, which are fully ionized at physiological pH and neutralized at acidic pH values (pKs between 2 and 4) (27). In contrast, the net charge on TM collagen constituents is small at physiological pH because the net charge of amino (NH 3 + ) and carboxyl groups is z...

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“…1A. For example, the outer hair cells of the mammalian cochlea are directly linked via their hair bundles to the tectorial membrane, which is an elastic polymer network (24). Otolithic membranes can also provide an elastic coupling of hair bundles as for instance in the bullfrog's sacculus (25).…”

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confidence: 99%

Enhancement of sensitivity gain and frequency tuning by coupling of active hair bundles

Dierkes

Lindner

Jülicher

2008

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

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The vertebrate inner ear possesses an active process that provides nonlinear amplification of mechanical stimuli. A candidate for this process is active hair bundle mechanics observed, for instance, for hair cells of the bullfrog's sacculus. Hair bundles in various inner ear organs are coupled by overlying membranes. Using a stochastic description of active hair bundle dynamics, we study the consequences of an elastic coupling on the properties of amplification. We report that collective effects in arrays of hair bundles can enhance the amplification gain and the sharpness of frequency tuning as compared with the performance of an isolated hair bundle. We also discuss the transient response elicited by the sudden onset of a periodic stimulus and its relation to temporal integration curves. Simulations of systems with a gradient of intrinsic frequencies show an enhanced amplification gain while preserving a frequency gradient, provided the coupling strength is similar to the hair bundle stiffness. We relate our findings to the situation in the bullfrog's sacculus and the mammalian cochlea.auditory amplifier ͉ hair cells ͉ nonlinear oscillators ͉ stochastic processes T he extraordinary ability of the vertebrate ear to detect sound stimuli over many orders of magnitude in sound amplitude relies on active processes. The key features of the auditory amplifier are (i) the amplification of weak stimuli, (ii) a compressive nonlinearity for stronger stimuli, (iii) frequency selectivity, and (iv) the generation of spontaneous emissions (1-3). All these properties could be understood as the consequence of nonlinear dynamic oscillators that operate in the ear (4-7).

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Static material properties of the tectorial membrane: a summary

Cited by 46 publications

References 99 publications

Basilar Membrane and Tectorial Membrane Stiffness in the CBA/CaJ Mouse

Basilar Membrane and Tectorial Membrane Stiffness in the CBA/CaJ Mouse

Electrokinetic properties of the mammalian tectorial membrane

Enhancement of sensitivity gain and frequency tuning by coupling of active hair bundles

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