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Zhu Z, Reid W, George SS, Ou V, Ó Maoiléidigh D. 3D morphology of an outer-hair-cell hair bundle increases its displacement and dynamic range. Biophys J 2024; 123:3433-3451. [PMID: 39161094 PMCID: PMC11480765 DOI: 10.1016/j.bpj.2024.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 05/22/2024] [Accepted: 08/13/2024] [Indexed: 08/21/2024] Open
Abstract
In mammals, outer-hair-cell hair bundles (OHBs) transduce sound-induced forces into receptor currents and are required for the wide dynamic range and high sensitivity of hearing. OHBs differ conspicuously in morphology from other types of bundles. Here, we show that the 3D morphology of an OHB greatly impacts its mechanics and transduction. An OHB comprises rod-like stereocilia, which pivot on the surface of its sensory outer hair cell. Stereocilium pivot positions are arranged in columns and form a V shape. We measure the pivot positions and determine that OHB columns are far from parallel. To calculate the consequences of an OHB's V shape and far-from-parallel columns, we develop a mathematical model of an OHB that relates its pivot positions, 3D morphology, mechanics, and receptor current. We find that the 3D morphology of the OHB can halve its stiffness, can double its damping coefficient, and causes stereocilium displacements driven by stimulus forces to differ substantially across the OHB. Stereocilium displacements drive the opening and closing of ion channels through which the receptor current flows. Owing to the stereocilium-displacement differences, the currents passing through the ion channels can peak versus the stimulus frequency and vary considerably across the OHB. Consequently, the receptor current peaks versus the stimulus frequency. Ultimately, the OHB's 3D morphology can increase its receptor-current dynamic range more than twofold. Our findings imply that potential pivot-position changes owing to development, mutations, or location within the mammalian auditory organ might greatly alter OHB function.
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Affiliation(s)
- Zenghao Zhu
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Wisam Reid
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California; Harvard Medical School, Boston, Massachusetts
| | - Shefin Sam George
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Victoria Ou
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Dáibhid Ó Maoiléidigh
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California.
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2
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Lukashkin AN, Russell IJ, Rybdylova O. Local cochlear mechanical responses revealed through outer hair cell receptor potential measurements. Biophys J 2024; 123:3163-3175. [PMID: 39014895 PMCID: PMC11427782 DOI: 10.1016/j.bpj.2024.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 03/26/2024] [Accepted: 07/12/2024] [Indexed: 07/18/2024] Open
Abstract
Sensory hair cells, including the sensorimotor outer hair cells, which enable the sensitive, sharply tuned responses of the mammalian cochlea, are excited by radial shear between the organ of Corti and the overlying tectorial membrane. It is not currently possible to measure directly in vivo mechanical responses in the narrow cleft between the tectorial membrane and organ of Corti over a wide range of stimulus frequencies and intensities. The mechanical responses can, however, be derived by measuring hair cell receptor potentials. We demonstrate that the seemingly complex frequency- and intensity-dependent behavior of outer hair cell receptor potentials could be qualitatively explained by a two degrees of freedom system with local cochlear partition and tectorial membrane resonances strongly coupled by the outer hair cell stereocilia. A local minimum in the receptor potential below the characteristic frequency should always be observed at a frequency where the tectorial membrane mechanical impedance is minimal, i.e., at the presumed tectorial membrane resonance frequency. The tectorial membrane resonance frequency might, however, shift with stimulus intensity in accordance with a shift in the maximum of the tectorial membrane radial mechanical responses to lower frequencies, as observed in experiments.
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Affiliation(s)
- Andrei N Lukashkin
- Sensory Neuroscience Research Group, School of Applied Science, University of Brighton, Brighton, United Kingdom.
| | - Ian J Russell
- Sensory Neuroscience Research Group, School of Applied Science, University of Brighton, Brighton, United Kingdom
| | - Oyuna Rybdylova
- Advanced Engineering Centre, School of Architecture, Technology and Engineering, University of Brighton, Brighton, United Kingdom.
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3
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Park S, Kim H, Woo M, Kim M. Label-free detection of leukemic myeloblasts in hyaluronic acid. J Biol Eng 2022; 16:29. [PMID: 36319989 PMCID: PMC9628021 DOI: 10.1186/s13036-022-00308-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022] Open
Abstract
Chronic myeloid leukemia is generally required bone marrow biopsy for diagnosis. Although examining peripheral blood is less invasive, it has not been fully validated as a routine diagnostic test due to suboptimal sensitivity. To overcome this limitation, a number of methodologies based on microfluidics have been developed for sorting circulating tumor cells from peripheral blood of patients with leukemia. In order to develop a more convenient method, we designed an analysis protocol using motion microscopy that amplifies cellular micro motions in a captured video by re-rendering pixels to generate extreme magnified visuals. Intriguingly, no fluctuations around leukemic myeloblasts were observed with a motion microscope at any wavelength of 0–10 Hz. However, use of 0.05% hyaluronic acid, one type of non-newtonian fluid, demonstrated fluctuations around leukemic myeloblasts under conditions of 25 μm/s and 0.5–1.5 Hz with a motion microscope. Thus, the non-invasive detection of leukemic myeloblasts can offer a valuable supplementary diagnostic tool for assessment of drug efficacy for monitoring patients with chronic myeloid leukemia.
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Affiliation(s)
- Suhyun Park
- grid.255649.90000 0001 2171 7754Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07804 Republic of Korea
| | - Hyueyun Kim
- grid.255649.90000 0001 2171 7754Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07804 Republic of Korea
| | - Minna Woo
- grid.231844.80000 0004 0474 0428Department of Medicine, Toronto General Hospital Research Institute and Division of Endocrinology and Metabolism, University Health Network, University of Toronto, Toronto, ON Canada
| | - Minsuk Kim
- grid.255649.90000 0001 2171 7754Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07804 Republic of Korea
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4
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Zosuls A, Rupprecht LC, Mountain DC. Inner hair cell stereocilia displacement in response to focal stimulation of the basilar membrane in the ex vivo gerbil cochlea. Hear Res 2021; 412:108372. [PMID: 34775267 PMCID: PMC8756456 DOI: 10.1016/j.heares.2021.108372] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 10/03/2021] [Accepted: 10/13/2021] [Indexed: 12/01/2022]
Abstract
The inner hair cells in the mammalian cochlea transduce mechanical signals to electrical signals that provide input to the auditory nerve. The spatial-temporal displacement of the inner hair cell stereocilia (IHCsc) relative to basilar membrane (BM) displacement is central to characterizing the transduction process. This study specifically focuses on measuring displacement of the stereocilia hair bundles in the radial dimensions where they are most sensitive. To simplify the mechanical response of the cochlear partition, a mechanical probe was used to drive the BM. Optical imaging was used to measure radial displacement of the inner hair cell stereocilia local to the probe in ex vivo gerbil cochleae. The mechanical probe displaced the BM in the transverse direction using sinusoidal stimuli with frequencies ranging from 10 Hz to 42.5 kHz. IHCsc displacement measurements were made in the radial dimension as a function of their longitudinal location along the length of the BM. The results were used to quantify the frequency response, longitudinal space coupling, traveling wave velocity, and wavelength of the radial displacement of the stereocilia. The measurements were centered at two best frequency locations along the BM: Proximal to the round window (first turn), and in the second turn. At both locations, frequency tuning was seen that was consistent with published place maps. At both locations, traveling waves were observed simultaneously propagating basal and apical from the probe. The velocity of the traveling waves at the center frequency (CF) of the location was higher in the first turn than in the second. As the stimulus frequency increased and approached CF for a location, the traveling wavelength decreased. Differential motion of the BM and IHCsc was observed in the second turn as the stimulus frequency increased toward CF. The longitudinal coupling measured in this study was longer than observed in previous studies. In summary the results suggest that the shape of the wave patterns present on the BM are not sufficient to characterize the displacement of the IHCsc.
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Affiliation(s)
- Aleksandrs Zosuls
- Hearing Research Center, Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, 02215, MA, United States.
| | - Laura C Rupprecht
- Hearing Research Center, Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, 02215, MA, United States.
| | - David C Mountain
- Hearing Research Center, Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, 02215, MA, United States
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5
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Mansour A, Sellon JB, Filizzola D, Ghaffari R, Cheatham MA, Freeman DM. Age-related degradation of tectorial membrane dynamics with loss of CEACAM16. Biophys J 2021; 120:4777-4785. [PMID: 34555361 PMCID: PMC8595744 DOI: 10.1016/j.bpj.2021.09.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/01/2021] [Accepted: 09/16/2021] [Indexed: 11/29/2022] Open
Abstract
Studies of genetic disorders of sensorineural hearing loss have been instrumental in delineating mechanisms that underlie the remarkable sensitivity and selectivity that are hallmarks of mammalian hearing. For example, genetic modifications of TECTA and TECTB, which are principal proteins that comprise the tectorial membrane (TM), have been shown to alter auditory thresholds and frequency tuning in ways that can be understood in terms of changes in the mechanical properties of the TM. Here, we investigate effects of genetic modification targeting CEACAM16, a third important TM protein. Loss of CEACAM16 has been recently shown to lead to progressive reductions in sensitivity. Whereas age-related hearing losses have previously been linked to changes in sensory receptor cells, the role of the TM in progressive hearing loss is largely unknown. Here, we show that TM stiffness and viscosity are significantly reduced in adult mice that lack functional CEACAM16 relative to age-matched wild-type controls. By contrast, these same mechanical properties of TMs from juvenile mice that lack functional CEACAM16 are more similar to those of wild-type mice. Thus, changes in hearing phenotype align with changes in TM material properties and can be understood in terms of the same TM wave properties that were previously used to characterize modifications of TECTA and TECTB. These results demonstrate that CEACAM16 is essential for maintaining TM mechanical and wave properties, which in turn are necessary for sustaining the remarkable sensitivity and selectivity of mammalian hearing with increasing age.
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Affiliation(s)
- Amer Mansour
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jonathan B Sellon
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Daniel Filizzola
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Mary Ann Cheatham
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Knowles Hearing Center, Northwestern University, Evanston, Illinois
| | - Dennis M Freeman
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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Xiong Y, Li S, Gu C, Meng G, Peng Z. Millimeter-Wave Bat for Mapping and Quantifying Micromotions in Full Field of View. RESEARCH (WASHINGTON, D.C.) 2021; 2021:9787484. [PMID: 34485917 PMCID: PMC8385533 DOI: 10.34133/2021/9787484] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/04/2021] [Indexed: 11/16/2022]
Abstract
Echolocating bats possess remarkable capability of multitarget spatial localization and micromotion sensing in a full field of view (FFOV) even in cluttered environments. Artificial technologies with such capability are highly desirable for various fields. However, current techniques such as visual sensing and laser scanning suffer from numerous fundamental problems. Here, we develop a bioinspired concept of millimeter-wave (mmWave) full-field micromotion sensing, creating a unique mmWave Bat ("mmWBat"), which can map and quantify tiny motions spanning macroscopic to μm length scales of full-field targets simultaneously and accurately. In mmWBat, we show that the micromotions can be measured via the interferometric phase evolution tracking from range-angle joint dimension, integrating with full-field localization and tricky clutter elimination. With our approach, we demonstrate the capacity to solve challenges in three disparate applications: multiperson vital sign monitoring, full-field mechanical vibration measurement, and multiple sound source localization and reconstruction (radiofrequency microphone). Our work could potentially revolutionize full-field micromotion monitoring in a wide spectrum of applications, while may inspiring novel biomimetic wireless sensing systems.
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Affiliation(s)
- Yuyong Xiong
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Songxu Li
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Changzhan Gu
- MoE Key Lab of Design and Electromagnetic Compatibility of High Speed Electronic System, and MoE Key Lab of Artificial Intelligence, AI Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Guang Meng
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhike Peng
- State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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7
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Cheatham MA. Spontaneous otoacoustic emissions are biomarkers for mice with tectorial membrane defects. Hear Res 2021; 409:108314. [PMID: 34332206 DOI: 10.1016/j.heares.2021.108314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/22/2021] [Accepted: 07/12/2021] [Indexed: 01/12/2023]
Abstract
Cochlear function depends on the operation of a coupled feedback loop, incorporating outer hair cells (OHCs), and structured to assure that inner hair cells (IHCs) convey frequency specific acoustic information to the brain, even at very low sound levels. Although our knowledge of OHC function and its contribution to cochlear amplification has expanded, the importance of the tectorial membrane (TM) to the processing of mechanical inputs has not been fully elucidated. In addition, there are a surprising number of genetic mutations that affect TM structure and that produce hearing loss in humans. By synthesizing old and new results obtained on several mouse mutants, we learned that animals with abnormal TMs are prone to generate spontaneous otoacoustic emissions (SOAE), which are uncommon in most wildtype laboratory animals. Because SOAEs are not produced in TM mutants or in humans when threshold shifts exceed approximately 25 dB, some degree of cochlear amplification is required. However, amplification by itself is not sufficient because normal mice are rarely spontaneous emitters. Since SOAEs reflect active cochlear operation, TM mutants are valuable for studying the oscillatory nature of the amplification process and the structures associated with its stabilization. Inasmuch as the mouse models were selected to mirror human auditory disorders, using SOAEs as a noninvasive clinical tool may assist the classification of individuals with genetic defects that influence the active mechanisms responsible for sensitivity and frequency selectivity, the hallmarks of mammalian hearing.
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Affiliation(s)
- Mary Ann Cheatham
- The Knowles Hearing Center, Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2-240 Frances Searle Building, 2240 Campus Drive, Evanston, IL 60208, USA.
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8
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Liu S, Wang S, Zou L, Xiong W. Mechanisms in cochlear hair cell mechano-electrical transduction for acquisition of sound frequency and intensity. Cell Mol Life Sci 2021; 78:5083-5094. [PMID: 33871677 PMCID: PMC11072359 DOI: 10.1007/s00018-021-03840-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 03/30/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Sound signals are acquired and digitized in the cochlea by the hair cells that further transmit the coded information to the central auditory pathways. Any defect in hair cell function may induce problems in the auditory system and hearing-based brain function. In the past 2 decades, our understanding of auditory transduction has been substantially deepened because of advances in molecular, structural, and functional studies. Results from these experiments can be perfectly embedded in the previously established profile from anatomical, histological, genetic, and biophysical research. This review aims to summarize the progress on the molecular and cellular mechanisms of the mechano-electrical transduction (MET) channel in the cochlear hair cells, which is involved in the acquisition of sound frequency and intensity-the two major parameters of an acoustic cue. We also discuss recent studies on TMC1, the molecule likely to form the MET channel pore.
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Affiliation(s)
- Shuang Liu
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Shufeng Wang
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Linzhi Zou
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Wei Xiong
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China.
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China.
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9
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Lanoy M, Lemoult F, Eddi A, Prada C. Dirac cones and chiral selection of elastic waves in a soft strip. Proc Natl Acad Sci U S A 2020; 117:30186-30190. [PMID: 33208536 PMCID: PMC7720205 DOI: 10.1073/pnas.2010812117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We study the propagation of in-plane elastic waves in a soft thin strip, a specific geometrical and mechanical hybrid framework which we expect to exhibit a Dirac-like cone. We separate the low frequencies guided modes (typically 100 Hz for a 1-cm-wide strip) and obtain experimentally the full dispersion diagram. Dirac cones are evidenced together with other remarkable wave phenomena such as negative wave velocity or pseudo-zero group velocity (ZGV). Our measurements are convincingly supported by a model (and numerical simulation) for both Neumann and Dirichlet boundary conditions. Finally, we perform one-way chiral selection by carefully setting the source position and polarization. Therefore, we show that soft materials support atypical wave-based phenomena, which is all of the more interesting as they make most of the biological tissues.
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Affiliation(s)
- Maxime Lanoy
- Institut Langevin, Ecole Supérieure de Physique et de Chimie Industrielles (ESPCI) Paris, Paris Sciences et Lettres (PSL) University, CNRS, 75005 Paris, France;
| | - Fabrice Lemoult
- Institut Langevin, Ecole Supérieure de Physique et de Chimie Industrielles (ESPCI) Paris, Paris Sciences et Lettres (PSL) University, CNRS, 75005 Paris, France
| | - Antonin Eddi
- Physique et Mécanique des Milieux Hétérogènes, CNRS, ESPCI Paris, Université PSL, Sorbonne Université, Université de Paris, F-75005, Paris, France
| | - Claire Prada
- Institut Langevin, Ecole Supérieure de Physique et de Chimie Industrielles (ESPCI) Paris, Paris Sciences et Lettres (PSL) University, CNRS, 75005 Paris, France
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10
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Cochlear development, cellular patterning and tonotopy. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Walls WD, Moteki H, Thomas TR, Nishio SY, Yoshimura H, Iwasa Y, Frees KL, Nishimura CJ, Azaiez H, Booth KT, Marini RJ, Kolbe DL, Weaver AM, Schaefer AM, Wang K, Braun TA, Usami SI, Barr-Gillespie PG, Richardson GP, Smith RJ, Casavant TL. A comparative analysis of genetic hearing loss phenotypes in European/American and Japanese populations. Hum Genet 2020; 139:1315-1323. [PMID: 32382995 DOI: 10.1007/s00439-020-02174-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 04/29/2020] [Indexed: 01/04/2023]
Abstract
We present detailed comparative analyses to assess population-level differences in patterns of genetic deafness between European/American and Japanese cohorts with non-syndromic hearing loss. One thousand eighty-three audiometric test results (921 European/American and 162 Japanese) from members of 168 families (48 European/American and 120 Japanese) with non-syndromic hearing loss secondary to pathogenic variants in one of three genes (KCNQ4, TECTA, WFS1) were studied. Audioprofile characteristics, specific mutation types, and protein domains were considered in the comparative analyses. Our findings support differences in audioprofiles driven by both mutation type (non-truncating vs. truncating) and ethnic background. The former finding confirms data that ascribe a phenotypic consequence to different mutation types in KCNQ4; the latter finding suggests that there are ethnic-specific effects (genetic and/or environmental) that impact gene-specific audioprofiles for TECTA and WFS1. Identifying the drivers of ethnic differences will refine our understanding of phenotype-genotype relationships and the biology of hearing and deafness.
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Affiliation(s)
- W Daniel Walls
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, 390-8621, Japan
| | - Taylor R Thomas
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, 390-8621, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, 390-8621, Japan
| | - Yoichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, 390-8621, Japan
| | - Kathy L Frees
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Carla J Nishimura
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Hela Azaiez
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Kevin T Booth
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.,Department of Neurobiology, Harvard Medical School, Boston, MA, 02215, USA
| | - Robert J Marini
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Diana L Kolbe
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - A Monique Weaver
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Amanda M Schaefer
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Kai Wang
- Department of Biostatistics, University of Iowa, Iowa City, IA, 52242, USA
| | - Terry A Braun
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Nagano, 390-8621, Japan
| | | | - Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, UK
| | - Richard J Smith
- Molecular Otolaryngology and Renal Research Labs, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA. .,Interdepartmental Ph.D. Program in Genetics, University of Iowa, Iowa City, IA, 52242, USA. .,Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.
| | - Thomas L Casavant
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, 52242, USA.,Center for Bioinformatics and Computational Biology, University of Iowa, Iowa City, IA, 52242, USA.,Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA, 52242, USA
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12
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Kim H, Ahn YH, Kim BS, Park S, Yoon JC, Park J, Moon CM, Ryu DR, Lee Kang J, Choi JH, Park EM, Lee KE, Woo M, Kim M. Motion microscopy for label-free detection of circulating breast tumor cells. Biosens Bioelectron 2020; 158:112131. [PMID: 32275204 DOI: 10.1016/j.bios.2020.112131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/23/2019] [Accepted: 03/02/2020] [Indexed: 12/19/2022]
Abstract
Circulating tumor cells (CTCs) are cancer cells that have been shed from a primary tumor and circulate in the bloodstream during progression of cancer. They may thus serve as circulating biomarkers that can predict, diagnose and guide therapy. Moreover, phenotypic and genotypic analysis of CTCs can facilitate prospective assessment of mutations and enable personalized treatment. A number of methodologies based on biological and physical differences between circulating tumor and non-tumor cells have been developed over the past few years. However, these methods did not have sufficient sensitivity or specificity. In this work, a remote analysis protocol was designed using motion microscopy that amplifies cellular micro motions in a captured video by re-rendering small motions to generate extreme magnified visuals to detect dynamic motions that are not otherwise visible by naked eye. Intriguingly, motion microscopy demonstrated fluctuations around breast tumor cells, which we referred to herein as cellular trail. Phenomena of cellular trail mostly emerged between 0.5 and 1.5 Hz on amplified video images. Interestingly, cellular trails were associated with cell surface proteins and flow rates rather than mitochondrial activity. Moreover, cellular trails were present only around circulating tumor cells from individuals with breast cancer under conditions of 20-30 μm/s and 0.5-1.5 Hz. Thus, motion microscopy based CTC detection method can offer a valuable supplementary diagnostic tool for assessment of drug efficacy and identifying physical characteristics of tumor cells for further research.
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Affiliation(s)
- Hyueyun Kim
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Young-Ho Ahn
- Department of Molecular Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Bom Sahn Kim
- Department of Nuclear Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Sanghui Park
- Department of Pathology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Joo Chun Yoon
- Department of Microbiology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Junbeom Park
- Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Chang Mo Moon
- Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Dong-Ryeol Ryu
- Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Jihee Lee Kang
- Department of Physiology and Tissue Injury Defense Research Center, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Ji Ha Choi
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Eun-Mi Park
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Kyung Eun Lee
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Minna Woo
- Toronto General Hospital Research Institute and Division of Endocrinology and Metabolism, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Minsuk Kim
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
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13
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Laurent J, Royer D, Prada C. In-plane backward and zero group velocity guided modes in rigid and soft strips. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 147:1302. [PMID: 32113319 DOI: 10.1121/10.0000760] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 02/01/2020] [Indexed: 06/10/2023]
Abstract
Elastic waves guided along bars of rectangular cross sections exhibit complex dispersion. This paper studies in-plane modes propagating at low frequencies in thin isotropic rectangular waveguides through experiments and numerical simulations. These modes result from the coupling at the edge between the first order shear horizontal mode SH0 of phase velocity equal to the shear velocity VT and the first order symmetrical Lamb mode S0 of phase velocity equal to the plate velocity VP. In the low frequency domain, the dispersion curves of these modes are close to those of Lamb modes propagating in plates of bulk wave velocities VP and VT. The dispersion curves of backward modes and the associated zero group velocity (ZGV) resonances are measured in a metal tape using noncontact laser ultrasonic techniques. Numerical calculations of in-plane modes in a soft ribbon of Poisson's ratio ν≈0.5 confirm that, due to very low shear velocity, backward waves and ZGV modes exist at frequencies that are hundreds of times lower than ZGV resonances in metal tapes of the same geometry. The results are compared to theoretical dispersion curves calculated using the method provided in Krushynska and Meleshko [J. Acoust. Soc. Am. 129, 1324-1335 (2011)].
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Affiliation(s)
- Jérôme Laurent
- Ecole Supérieure de Physique et de Chimie de la ville de Paris, Paris Sciences et Lettres University, Centre National de la Recherche Scientifique, Institut Langevin, 1 rue Jussieu, Paris, France
| | - Daniel Royer
- Ecole Supérieure de Physique et de Chimie de la ville de Paris, Paris Sciences et Lettres University, Centre National de la Recherche Scientifique, Institut Langevin, 1 rue Jussieu, Paris, France
| | - Claire Prada
- Ecole Supérieure de Physique et de Chimie de la ville de Paris, Paris Sciences et Lettres University, Centre National de la Recherche Scientifique, Institut Langevin, 1 rue Jussieu, Paris, France
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14
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Sellon JB, Ghaffari R, Freeman DM. The Tectorial Membrane: Mechanical Properties and Functions. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033514. [PMID: 30348837 DOI: 10.1101/cshperspect.a033514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The tectorial membrane (TM) is widely believed to play a critical role in determining the remarkable sensitivity and frequency selectivity that are hallmarks of mammalian hearing. Recently developed mouse models of human hearing disorders have provided new insights into the molecular, nanomechanical mechanisms that underlie resonance and traveling wave properties of the TM. Herein we review recent experimental and theoretical results detailing TM morphology, local poroelastic and electromechanical interactions, and global spread of excitation via TM traveling waves, with direct implications for cochlear mechanisms.
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Affiliation(s)
- Jonathan B Sellon
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139
| | - Dennis M Freeman
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139.,Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts 02139
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15
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Burwood GWS, Fridberger A, Wang RK, Nuttall AL. Revealing the morphology and function of the cochlea and middle ear with optical coherence tomography. Quant Imaging Med Surg 2019; 9:858-881. [PMID: 31281781 PMCID: PMC6571188 DOI: 10.21037/qims.2019.05.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 05/09/2019] [Indexed: 01/17/2023]
Abstract
Optical coherence tomography (OCT) has revolutionized physiological studies of the hearing organ, the vibration and morphology of which can now be measured without opening the surrounding bone. In this review, we provide an overview of OCT as used in the otological research, describing advances and different techniques in vibrometry, angiography, and structural imaging.
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Affiliation(s)
- George W. S. Burwood
- Department of Otolaryngology, Oregon Hearing Research Center/HNS, Oregon Health & Science University, Portland, OR, USA
| | - Anders Fridberger
- Department of Otolaryngology, Oregon Hearing Research Center/HNS, Oregon Health & Science University, Portland, OR, USA
- Department of Clinical and Experimental Medicine, Section for Neurobiology, Linköping University, Linköping, Sweden
| | - Ruikang K. Wang
- Department of Bioengineering and Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Alfred L. Nuttall
- Department of Otolaryngology, Oregon Hearing Research Center/HNS, Oregon Health & Science University, Portland, OR, USA
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16
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Sellon JB, Azadi M, Oftadeh R, Nia HT, Ghaffari R, Grodzinsky AJ, Freeman DM. Nanoscale Poroelasticity of the Tectorial Membrane Determines Hair Bundle Deflections. PHYSICAL REVIEW LETTERS 2019; 122:028101. [PMID: 30720330 PMCID: PMC6813812 DOI: 10.1103/physrevlett.122.028101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 10/14/2018] [Indexed: 06/09/2023]
Abstract
Stereociliary imprints in the tectorial membrane (TM) have been taken as evidence that outer hair cells are sensitive to shearing displacements of the TM, which plays a key role in shaping cochlear sensitivity and frequency selectivity via resonance and traveling wave mechanisms. However, the TM is highly hydrated (97% water by weight), suggesting that the TM may be flexible even at the level of single hair cells. Here we show that nanoscale oscillatory displacements of microscale spherical probes in contact with the TM are resisted by frequency-dependent forces that are in phase with TM displacement at low and high frequencies, but are in phase with TM velocity at transition frequencies. The phase lead can be as much as a quarter of a cycle, thereby contributing to frequency selectivity and stability of cochlear amplification.
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Affiliation(s)
- Jonathan B. Sellon
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Mojtaba Azadi
- School of Engineering, College of Science and Engineering, San Francisco State University, San Francisco, CA 94132, USA
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ramin Oftadeh
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hadi Tavakoli Nia
- Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Alan J. Grodzinsky
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Dennis M. Freeman
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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17
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Amplification and Suppression of Traveling Waves along the Mouse Organ of Corti: Evidence for Spatial Variation in the Longitudinal Coupling of Outer Hair Cell-Generated Forces. J Neurosci 2019; 39:1805-1816. [PMID: 30651330 DOI: 10.1523/jneurosci.2608-18.2019] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 01/06/2019] [Accepted: 01/09/2019] [Indexed: 11/21/2022] Open
Abstract
Mammalian hearing sensitivity and frequency selectivity depend on a mechanical amplification process mediated by outer hair cells (OHCs). OHCs are situated within the organ of Corti atop the basilar membrane (BM), which supports sound-evoked traveling waves. It is well established that OHCs generate force to selectively amplify BM traveling waves where they peak, and that amplification accumulates from one location to the next over this narrow cochlear region. However, recent measurements demonstrate that traveling waves along the apical surface of the organ of Corti, the reticular lamina (RL), are amplified over a much broader region. Whether OHC forces accumulate along the length of the RL traveling wave to provide a form of "global" cochlear amplification is unclear. Here we examined the spatial accumulation of RL amplification. In mice of either sex, we used tones to suppress amplification from different cochlear regions and examined the effect on RL vibrations near and far from the traveling-wave peak. We found that although OHC forces amplify the entire RL traveling wave, amplification only accumulates near the peak, over the same region where BM motion is amplified. This contradicts the notion that RL motion is involved in a global amplification mechanism and reveals that the mechanical properties of the BM and organ of Corti tune how OHC forces accumulate spatially. Restricting the spatial buildup of amplification enhances frequency selectivity by sharpening the peaks of cochlear traveling waves and constrains the number of OHCs responsible for mechanical sensitivity at each location.SIGNIFICANCE STATEMENT Outer hair cells generate force to amplify traveling waves within the mammalian cochlea. This force generation is critical to the ability to detect and discriminate sounds. Nevertheless, how these forces couple to the motions of the surrounding structures and integrate along the cochlear length remains poorly understood. Here we demonstrate that outer hair cell-generated forces amplify traveling-wave motion on the organ of Corti throughout the wave's extent, but that these forces only accumulate longitudinally over a region near the wave's peak. The longitudinal coupling of outer hair cell-generated forces is therefore spatially tuned, likely by the mechanical properties of the basilar membrane and organ of Corti. Our findings provide new insight into the mechanical processes that underlie sensitive hearing.
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18
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Lemons C, Sellon JB, Boatti E, Filizzola D, Freeman DM, Meaud J. Anisotropic Material Properties of Wild-Type and Tectb -/- Tectorial Membranes. Biophys J 2019; 116:573-585. [PMID: 30665694 DOI: 10.1016/j.bpj.2018.12.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/28/2018] [Accepted: 12/28/2018] [Indexed: 10/27/2022] Open
Abstract
The tectorial membrane (TM) is an extracellular matrix that is directly coupled with the mechanoelectrical receptors responsible for sensory transduction and amplification. As such, the TM is often hypothesized to play a key role in the remarkable sensory abilities of the mammalian cochlea. Genetic studies targeting TM proteins have shown that changes in TM structure dramatically affect cochlear function in mice. Precise information about the mechanical properties of the TMs of wild-type and mutant mice at audio frequencies is required to elucidate the role of the TM and to understand how these genetic mutations affect cochlear mechanics. In this study, images of isolated TM segments are used to determine both the radial and longitudinal motions of the TM in response to a harmonic radial excitation. The resulting longitudinally propagating radial displacement and highly spatially dependent longitudinal displacement are modeled using finite-element models that take into account the anisotropy and finite dimensions of TMs. An automated, least-square fitting algorithm is used to find the anisotropic material properties of wild-type and Tectb-/- mice at audio frequencies. Within the auditory frequency range, it is found that the TM is a highly viscoelastic and anisotropic structure with significantly higher stiffness in the direction of the collagen fibers. Although no decrease in the stiffness in the fiber direction is observed, the stiffness of the TM in shear and in the transverse direction is found to be significantly reduced in Tectb-/- mice. As a result, TMs of the mutant mice tend to be significantly more anisotropic within the frequency range examined in this study. The effects of the Tectb-/- mutation on the TM's anisotropic material properties may be responsible for the changes in cochlear tuning and sensitivity that have been previously reported for these mice.
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Affiliation(s)
- Charlsie Lemons
- G.W.W. School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Jonathan B Sellon
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Elisa Boatti
- G.W.W. School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Daniel Filizzola
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Dennis M Freeman
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Julien Meaud
- G.W.W. School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia; Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.
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19
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Bell A, Wit HP. Cochlear impulse responses resolved into sets of gammatones: the case for beating of closely spaced local resonances. PeerJ 2018; 6:e6016. [PMID: 30515362 PMCID: PMC6266938 DOI: 10.7717/peerj.6016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 10/27/2018] [Indexed: 02/05/2023] Open
Abstract
Gammatones have had a long history in auditory studies, and recent theoretical work suggests they may play an important role in cochlear mechanics as well. Following this lead, the present paper takes five examples of basilar membrane impulse responses and uses a curve-fitting algorithm to decompose them into a number of discrete gammatones. The limits of this ‘sum of gammatones’ (SOG) method to accurately represent the impulse response waveforms were tested and it was found that at least two and up to six gammatones could be isolated from each example. Their frequencies were stable and largely independent of stimulus parameters. The gammatones typically formed a regular series in which the frequency ratio between successive members was about 1.1. Adding together the first few gammatones in a set produced beating-like waveforms which mimicked waxing and waning, and the instantaneous frequencies of the waveforms were also well reproduced, providing an explanation for frequency glides. Consideration was also given to the impulse response of a pair of elastically coupled masses—the basis of two-degree-of-freedom models comprised of coupled basilar and tectorial membranes—and the resulting waveform was similar to a pair of beating gammatones, perhaps explaining why the SOG method seems to work well in describing cochlear impulse responses. A major limitation of the SOG method is that it cannot distinguish a waveform resulting from an actual physical resonance from one derived from overfitting, but taken together the method points to the presence of a series of closely spaced local resonances in the cochlea.
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Affiliation(s)
- Andrew Bell
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Hero P Wit
- Department of Otorhinolaryngology/Head and Neck Surgery, University of Groningen, Groningen, Netherlands
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20
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Dewey JB, Xia A, Müller U, Belyantseva IA, Applegate BE, Oghalai JS. Mammalian Auditory Hair Cell Bundle Stiffness Affects Frequency Tuning by Increasing Coupling along the Length of the Cochlea. Cell Rep 2018; 23:2915-2927. [PMID: 29874579 PMCID: PMC6309882 DOI: 10.1016/j.celrep.2018.05.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/24/2018] [Accepted: 05/08/2018] [Indexed: 01/15/2023] Open
Abstract
The stereociliary bundles of cochlear hair cells convert mechanical vibrations into the electrical signals required for auditory sensation. While the stiffness of the bundles strongly influences mechanotransduction, its influence on the vibratory response of the cochlear partition is unclear. To assess this, we measured cochlear vibrations in mutant mice with reduced bundle stiffness or with a tectorial membrane (TM) that is detached from the sensory epithelium. We found that reducing bundle stiffness decreased the high-frequency extent and sharpened the tuning of vibratory responses obtained postmortem. Detaching the TM further reduced the high-frequency extent of the vibrations but also lowered the partition's resonant frequency. Together, these results demonstrate that the bundle's stiffness and attachment to the TM contribute to passive longitudinal coupling in the cochlea. We conclude that the stereociliary bundles and TM interact to facilitate passive-wave propagation to more apical locations, possibly enhancing active-wave amplification in vivo.
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Affiliation(s)
- James B Dewey
- The Caruso Department of Otolaryngology - Head & Neck Surgery, University of Southern California, Los Angeles, CA 90033, USA
| | - Anping Xia
- Department of Otolaryngology - Head & Neck Surgery, Stanford University, Stanford, CA 94305, USA
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - John S Oghalai
- The Caruso Department of Otolaryngology - Head & Neck Surgery, University of Southern California, Los Angeles, CA 90033, USA.
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21
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Abstract
Although the human visual system is remarkable at perceiving and interpreting motions, it has limited sensitivity, and we cannot see motions that are smaller than some threshold. Although difficult to visualize, tiny motions below this threshold are important and can reveal physical mechanisms, or be precursors to large motions in the case of mechanical failure. Here, we present a "motion microscope," a computational tool that quantifies tiny motions in videos and then visualizes them by producing a new video in which the motions are made large enough to see. Three scientific visualizations are shown, spanning macroscopic to nanoscopic length scales. They are the resonant vibrations of a bridge demonstrating simultaneous spatial and temporal modal analysis, micrometer vibrations of a metamaterial demonstrating wave propagation through an elastic matrix with embedded resonating units, and nanometer motions of an extracellular tissue found in the inner ear demonstrating a mechanism of frequency separation in hearing. In these instances, the motion microscope uncovers hidden dynamics over a variety of length scales, leading to the discovery of previously unknown phenomena.
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22
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Two-Dimensional Cochlear Micromechanics Measured In Vivo Demonstrate Radial Tuning within the Mouse Organ of Corti. J Neurosci 2017; 36:8160-73. [PMID: 27488636 DOI: 10.1523/jneurosci.1157-16.2016] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/07/2016] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED The exquisite sensitivity and frequency discrimination of mammalian hearing underlie the ability to understand complex speech in noise. This requires force generation by cochlear outer hair cells (OHCs) to amplify the basilar membrane traveling wave; however, it is unclear how amplification is achieved with sharp frequency tuning. Here we investigated the origin of tuning by measuring sound-induced 2-D vibrations within the mouse organ of Corti in vivo Our goal was to determine the transfer function relating the radial shear between the structures that deflect the OHC bundle, the tectorial membrane and reticular lamina, to the transverse motion of the basilar membrane. We found that, after normalizing their responses to the vibration of the basilar membrane, the radial vibrations of the tectorial membrane and reticular lamina were tuned. The radial tuning peaked at a higher frequency than transverse basilar membrane tuning in the passive, postmortem condition. The radial tuning was similar in dead mice, indicating that this reflected passive, not active, mechanics. These findings were exaggerated in Tecta(C1509G/C1509G) mice, where the tectorial membrane is detached from OHC stereocilia, arguing that the tuning of radial vibrations within the hair cell epithelium is distinct from tectorial membrane tuning. Together, these results reveal a passive, frequency-dependent contribution to cochlear filtering that is independent of basilar membrane filtering. These data argue that passive mechanics within the organ of Corti sharpen frequency selectivity by defining which OHCs enhance the vibration of the basilar membrane, thereby tuning the gain of cochlear amplification. SIGNIFICANCE STATEMENT Outer hair cells amplify the traveling wave within the mammalian cochlea. The resultant gain and frequency sharpening are necessary for speech discrimination, particularly in the presence of background noise. Here we measured the 2-D motion of the organ of Corti in mice and found that the structures that stimulate the outer hair cell stereocilia, the tectorial membrane and reticular lamina, were sharply tuned in the radial direction. Radial tuning was similar in dead mice and in mice lacking a tectorial membrane. This suggests that radial tuning comes from passive mechanics within the hair cell epithelium, and that these mechanics, at least in part, may tune the gain of cochlear amplification.
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23
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Sellon JB, Ghaffari R, Freeman DM. Geometric Requirements for Tectorial Membrane Traveling Waves in the Presence of Cochlear Loads. Biophys J 2017; 112:1059-1062. [PMID: 28237025 PMCID: PMC5375137 DOI: 10.1016/j.bpj.2017.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/25/2017] [Accepted: 02/03/2017] [Indexed: 11/30/2022] Open
Abstract
Recent studies suggest that wave motions of the tectorial membrane (TM) play a critical role in determining the frequency selectivity of hearing. However, frequency tuning is also thought to be limited by viscous loss in subtectorial fluid. Here, we analyze effects of this loss and other cochlear loads on TM traveling waves. Using a viscoelastic model, we demonstrate that hair bundle stiffness has little effect on TM traveling waves calculated with physiological parameters, that the limbal attachment can cause small (<20%) increases in TM wavelength, and that viscous loss in the subtectorial fluid can cause small (<20%) decreases in TM wave decay constants. However, effects of viscous loss in the subtectorial fluid are significantly increased if TM thickness is decreased. In contrast, increasing TM thickness above its physiological range has little effect on the wave, suggesting that the TM is just thick enough to maximize the spatial extent of the TM traveling wave.
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Affiliation(s)
- Jonathan B Sellon
- Harvard-MIT Program in Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts.
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Dennis M Freeman
- Harvard-MIT Program in Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
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24
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Farrahi S, Ghaffari R, Sellon JB, Nakajima HH, Freeman DM. Tectorial Membrane Traveling Waves Underlie Sharp Auditory Tuning in Humans. Biophys J 2016; 111:921-4. [PMID: 27544000 PMCID: PMC5018139 DOI: 10.1016/j.bpj.2016.07.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/15/2016] [Accepted: 07/20/2016] [Indexed: 11/25/2022] Open
Abstract
Our ability to understand speech requires neural tuning with high frequency resolution, but the peripheral mechanisms underlying sharp tuning in humans remain unclear. Sharp tuning in genetically modified mice has been attributed to decreases in spread of excitation of tectorial membrane traveling waves. Here we show that the spread of excitation of tectorial membrane waves is similar in humans and mice, although the mechanical excitation spans fewer frequencies in humans—suggesting a possible mechanism for sharper tuning.
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Affiliation(s)
- Shirin Farrahi
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jonathan B Sellon
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Harvard-MIT Program in Health Sciences and Technology, Cambridge, Massachusetts
| | - Hideko H Nakajima
- Department of Otolaryngology, Harvard Medical School and Massachusetts Eye and Ear, Boston, Massachusetts
| | - Dennis M Freeman
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts; Harvard-MIT Program in Health Sciences and Technology, Cambridge, Massachusetts.
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