Significance The remarkable high-frequency sensitivity of mammalian hearing depends on the amplification sound-evoked cochlear vibrations by outer hair cells. One way that cells are proposed to generate amplifying forces is through voltage-driven changes in cell length. However, it remains unclear whether this electromotility can work fast enough vivo provide at necessary frequencies. Here, we show sound elicits motions within living mouse cochlea fully consistent with electromotility. These...

Abstract While separating sounds into frequency components and subsequently converting them patterns of neural firing, the mammalian cochlea processes signal in ways that depend strongly on frequency. Indeed, both temporal structure response to transient stimuli sharpness tuning differ dramatically between apical basal (i.e., low- high-frequency) regions cochlea. Although mechanisms give rise these pronounced differences remain incompletely understood, they are generally attributed tonotopic...

Auditory inner hair cells (IHCs) convert sound vibrations into receptor potentials that drive synaptic transmission. For the precise encoding of qualities, are shaped by K+ conductances tuning properties IHC membrane. Using patch-clamp and computational modeling, we unravel this membrane specialization showing IHCs express an exclusive repertoire six voltage-dependent mediated Kv1.8, Kv7.4, Kv11.1, Kv12.1, BKCa channels. All channels active at rest but triggered differentially during...

The authors show that a simple, active cochlear model lacking direct vibration-amplification feedback explains the experimental data well. conclude amplifier boosts pressure waves without affecting local mechanical resonance of basilar membrane.

This paper presents an efficient method to compute the numerical solutions of transmission-line (TL) cochlear models, and its application on model Verhulst et al. The stability region is extended by adopting a variable step solve system ordinary differential equations that describes it, adaptive scheme take in account variations status within each step. presented leads improve simulations accuracy large computational savings, leading employ TL models for more extensive than currently possible.

The mammalian ear embeds a cellular amplifier that boosts sound-induced hydromechanical waves as they propagate along the cochlea. operation of this is not fully understood and difficult to disentangle experimentally. In prevailing view, cochlear are amplified by piezo-electric action outer hair cells (OHCs), whose cycle-by-cycle elongations contractions inject power into local motion basilar membrane (BM). Concomitant deformations opposing (or “top”) side organ Corti assumed play minor role...

The zero crossings of basilar-membrane (BM) responses to clicks are nearly independent stimulus intensity. This work explores the constraints that this invariance imposes on one-dimensional nonlinear cochlear models with two degrees freedom (2DoF). locations poles and zeros BM admittance, calculated for a set linear in which strength active force is progressively decreased, provides playground evaluating behavior corresponding model at increasing levels. Mathematical parameters derived by...

The intricate, crystalline cytoarchitecture of the mammalian organ Corti presumably plays an important role in cochlear amplification. As currently understood, oblique, Y-shaped arrangement outer hair cells (OHCs) and phalangeal processes Deiters serves to create differential “push–pull” forces that drive motion basilar membrane via spatial feedforward and/or feedbackward OHC forces. In concert with traveling wave, longitudinal separation between sensing forcing creates phase shifts yield a...

Measurements of basilar-membrane (BM) motion show that the compressive nonlinearity cochlear mechanical responses is not an instantaneous phenomenon. For this reason, amplifier has been thought to incorporate automatic gain control (AGC) mechanism characterized by a finite reaction time. This paper studies effect nonlinear damping on oscillatory systems. The principal results are (i) produces noninstantaneous differs markedly from typical AGC strategies; (ii) kinetics implied time system...

In animal experiments, the strong dependence on stimulus level of basilar membrane gain and tuning is not matched by a corresponding change in phase slope resonant region. Linear models, which has to be schematized explicitly changing parameters model, do easily match this feature experimental data. Nonlinear models predict that relatively decoupled from tuning. addition, delayed-stiffness feed-forward also show significant intrinsic decoupling between tuning, helps matching

This study proposes that the frequency tuning of inner-hair-cell (IHC) stereocilia in intact organ Corti can be derived from responses auditory fibers (AFs) using computational tools. The frequency-dependent relationship between AF threshold and amplitude vibration is estimated a model IHC-mediated mechanical to neural transduction. Depending on response properties considered AF, deflection required drive simulated above 1.4 9.2 dB smaller at low frequencies (≤500 Hz) than high (≥4 kHz)....

This study uses a 3-D representation of the cochlear fluid to extend results recent paper [Sisto, Belardinelli, and Moleti (2021b). J. Acoust. Soc. Am. 150, 4283-4296] in which two hydrodynamic effects, pressure focusing viscous damping BM motion, both associated with sharp increase wavenumber peak region, were analyzed for 2-D fluid, coupled standard 1-D transmission-line WKB approach modeling. The propagation equation is obtained from volume conservation equation, yielding effect, effect...

The extraordinary sensitivity of the mammalian inner ear has captivated scientists for decades, largely due to crucial role played by outer hair cells (OHCs) and their unique electromotile properties. Typically arranged in three rows along sensory epithelium, OHCs work concert via mechanisms collectively referred as ``cochlear amplifier'' boost cochlear response faint sounds. While simplistic views attribute this enhancement solely OHC-based increase gain, inevitable presence internal noise...

Two hydrodynamic effects are introduced in the standard transmission-line formalism, focusing of pressure and fluid velocity fields near basilar membrane viscous damping at fluid-basilar interface, which significantly affect cochlear response short-wave region. In this region, wavelength is shorter than duct height, only a layer order effectively involved traveling wave. This has been interpreted [8] as reduced contribution to system inertia peak viewpoint common 3-D FEM solutions. paper we...

Cochlear mechanics tends to be studied using single-location measurements of intracochlear vibrations in response acoustical stimuli. Such measurements, due their invasiveness and often the instability animal preparation, are difficult accomplish and, thus, ideally require stimulus paradigms that time efficient, flexible, result high resolution transfer functions. Here, a swept-sine method is adapted for recordings basilar membrane impulse responses mice. The frequency was exponentially...

In this study, we explore nonlinear cochlear amplification by analyzing basilar membrane (BM) motion in the mouse apex. Through vivo, postmortem, and mechanical suppression recordings, estimate how amplifier nonlinearly shapes wavenumber of BM traveling wave, specifically within a frequency range where short-wave approximation holds. Our findings demonstrate that straightforward mathematical model, depicting as modifier with strength diminishing monotonically displacement increases,...

Abstract The cochlea of the mammalian inner ear includes an active, hydromechanical amplifier thought to arise via piezoelectric action outer hair cells (OHCs). A classic problem cochlear biophysics is that long resistance-capacitance ( RC ) time constant hair-cell membrane produces effective cut-off frequency much lower than most audible sounds. implies OHC receptor potential—and hence its electromotile response—decreases by several orders magnitude over range hearing. This “ problem” often...