A two-dimensional cochlear fluid model based on conformal mapping

Lüling, Hannes; Franosch, Jan-Moritz P.; Hemmen, J. Leo van

doi:10.1121/1.3505108

Cited by 7 publications

(3 citation statements)

References 25 publications

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“…The first represents Q values in an active cochlea and the latter a passive or dead one. Further insight into the effect of coupling is provided by a paper [100] that uses a novel approach to cochlear modelling in which hydrodynamic coupling can be explicitly represented by a single parameter, c . When c = 0, there is no coupling and no travelling wave, only resonance.…”

Section: Discussionmentioning

confidence: 99%

A Resonance Approach to Cochlear Mechanics

Bell

2012

PLoS ONE

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BackgroundHow does the cochlea analyse sound into its component frequencies? In the 1850s Helmholtz thought it occurred by resonance, whereas a century later Békésy's work indicated a travelling wave. The latter answer seemed to settle the question, but with the discovery in 1978 that the cochlea emits sound, the mechanics of the cochlea was back on the drawing board. Recent studies have raised questions about whether the travelling wave, as currently understood, is adequate to explain observations.ApproachApplying basic resonance principles, this paper revisits the question. A graded bank of harmonic oscillators with cochlear-like frequencies and quality factors is simultaneously excited, and it is found that resonance gives rise to similar frequency responses, group delays, and travelling wave velocities as observed by experiment. The overall effect of the group delay gradient is to produce a decelerating wave of peak displacement moving from base to apex at characteristic travelling wave speeds. The extensive literature on chains of coupled oscillators is considered, and the occurrence of travelling waves, pseudowaves, phase plateaus, and forced resonance in such systems is noted.Conclusion and significanceThis alternative approach to cochlear mechanics shows that a travelling wave can simply arise as an apparently moving amplitude peak which passes along a bank of resonators without carrying energy. This highlights the possible role of the fast pressure wave and indicates how phase delays and group delays of a set of driven harmonic oscillators can generate an apparent travelling wave. It is possible to view the cochlea as a chain of globally forced coupled oscillators, and this model incorporates fundamental aspects of both the resonance and travelling wave theories.

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Section: Discussionmentioning

confidence: 99%

A Resonance Approach to Cochlear Mechanics

Bell

2012

PLoS ONE

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“…Instead, such systems rely on the membrane being placed on a closed channel, or either air or some fluid medium, such as water [68] or silicon oil [64]. The variation of the velocity of fluid flow in this channel generates a variation in the velocity potential [69], and hence the local pressure on the membrane; while the depth of the fluid channel increases, the fluid loading on the membrane reduces the resonance frequency (figure 3(C)) [70]. This, in combination with the slight spatial variation of the membrane's firstorder resonance peak with frequency, results in some degree of tonotopy.…”

Section: Bio-inspired Frequency Discriminating Sensorsmentioning

confidence: 99%

Review of the applications of principles of insect hearing to microscale acoustic engineering challenges

et al. 2023

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When looking for novel, simple, and energy-efficient solutions to engineering problems, nature has proved to be an incredibly valuable source of inspiration. The development of acoustic sensors has been a prolific field for bioinspired solutions. With a diverse array of evolutionary approaches to the problem of hearing at small scales (some widely different to the traditional concept of “ear”), insects in particular have served as a starting point for several designs. From locusts to moths, through crickets and mosquitoes among many others, the mechanisms found in nature to deal with small-scale acoustic detection and the engineering solutions they have inspired are reviewed. The present article is comprised of three main sections corresponding to the principal problems faced by insects, namely frequency discrimination, which is addressed by tonotopy, whether performed by a specific organ or directly on the tympana; directionality, with solutions including diverse adaptations to tympanal structure; and detection of weak signals, through what is known as active hearing. The three aforementioned problems concern tiny animals as much as human-manufactured microphones and have therefore been widely investigated. Even though bioinspired systems may not always provide perfect performance, they are sure to give us solutions with clever use of resources and minimal post-processing, being serious contenders for the best alternative depending on the requisites of the problem.

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“…In many cases, the 3D PDEs are adapted to simplified cases which afterward allow for solutions of the equations (c.f. e.g., van Hemmen Lüling et al, 2010 or Makram/Helmchen Markram et al, 1998 ). De Schutter et al calculated various processes (Bormann et al, 2001 ; Hepburn et al, 2013 ) with their Monte Carlo based STEPS package (Hepburn et al, 2012 ; Chen and De Schutter, 2014 ) which is exclusively written for calcium processes.…”

Section: Materials and Modelsmentioning

confidence: 99%

Influence of T-Bar on Calcium Concentration Impacting Release Probability

Knodel

Roy

Wittum

2022

Front. Comput. Neurosci.

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The relation of form and function, namely the impact of the synaptic anatomy on calcium dynamics in the presynaptic bouton, is a major challenge of present (computational) neuroscience at a cellular level. The Drosophila larval neuromuscular junction (NMJ) is a simple model system, which allows studying basic effects in a rather simple way. This synapse harbors several special structures. In particular, in opposite to standard vertebrate synapses, the presynaptic boutons are rather large, and they have several presynaptic zones. In these zones, different types of anatomical structures are present. Some of the zones bear a so-called T-bar, a particular anatomical structure. The geometric form of the T-bar resembles the shape of the letter “T” or a table with one leg. When an action potential arises, calcium influx is triggered. The probability of vesicle docking and neurotransmitter release is superlinearly proportional to the concentration of calcium close to the vesicular release site. It is tempting to assume that the T-bar causes some sort of calcium accumulation and hence triggers a higher release probability and thus enhances neurotransmitter exocytosis. In order to study this influence in a quantitative manner, we constructed a typical T-bar geometry and compared the calcium concentration close to the active zones (AZs). We compared the case of synapses with and without T-bars. Indeed, we found a substantial influence of the T-bar structure on the presynaptic calcium concentrations close to the AZs, indicating that this anatomical structure increases vesicle release probability. Therefore, our study reveals how the T-bar zone implies a strong relation between form and function. Our study answers the question of experimental studies (namely “Wichmann and Sigrist, Journal of neurogenetics 2010”) concerning the sense of the anatomical structure of the T-bar.

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A two-dimensional cochlear fluid model based on conformal mapping

Cited by 7 publications

References 25 publications

A Resonance Approach to Cochlear Mechanics

A Resonance Approach to Cochlear Mechanics

Review of the applications of principles of insect hearing to microscale acoustic engineering challenges

Influence of T-Bar on Calcium Concentration Impacting Release Probability

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