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Lazzeri G, Biagioni F, Ferrucci M, Puglisi-Allegra S, Lenzi P, Busceti CL, Giannessi F, Fornai F. The Relevance of Autophagy within Inner Ear in Baseline Conditions and Tinnitus-Related Syndromes. Int J Mol Sci 2023; 24:16664. [PMID: 38068993 PMCID: PMC10706730 DOI: 10.3390/ijms242316664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/07/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of outer hair cells (OHC) starting from the stereocilia (SC) occurs. This is common following ototoxic drugs, sound-induced ototoxicity, and acoustic degeneration. In all these conditions, altered coupling between the tectorial membrane (TM) and OHC SC is described. The present review analyzes the complex interactions involving OHC and TM. These need to be clarified to understand which mechanisms may underlie the onset of tinnitus and why the neuropathology of chronic degenerative tinnitus is similar, independent of early triggers. In fact, the fine neuropathology of tinnitus features altered mechanisms of mechanic-electrical transduction (MET) at the level of OHC SC. The appropriate coupling between OHC SC and TM strongly depends on autophagy. The involvement of autophagy may encompass degenerative and genetic tinnitus, as well as ototoxic drugs and acoustic trauma. Defective autophagy explains mitochondrial alterations and altered protein handling within OHC and TM. This is relevant for developing novel treatments that stimulate autophagy without carrying the burden of severe side effects. Specific phytochemicals, such as curcumin and berberin, acting as autophagy activators, may mitigate the neuropathology of tinnitus.
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Affiliation(s)
- Gloria Lazzeri
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Francesca Biagioni
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Michela Ferrucci
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Stefano Puglisi-Allegra
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Paola Lenzi
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Carla Letizia Busceti
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Francesco Giannessi
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Francesco Fornai
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
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Abolpour Moshizi S, Pastras CJ, Sharma R, Parvez Mahmud MA, Ryan R, Razmjou A, Asadnia M. Recent advancements in bioelectronic devices to interface with the peripheral vestibular system. Biosens Bioelectron 2022; 214:114521. [PMID: 35820254 DOI: 10.1016/j.bios.2022.114521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 06/23/2022] [Accepted: 06/27/2022] [Indexed: 11/26/2022]
Abstract
Balance disorders affect approximately 30% of the population throughout their lives and result in debilitating symptoms, such as spontaneous vertigo, nystagmus, and oscillopsia. The main cause of balance disorders is peripheral vestibular dysfunction, which may occur as a result of hair cell loss, neural dysfunction, or mechanical (and morphological) abnormality. The most common cause of vestibular dysfunction is arguably vestibular hair cell damage, which can result from an array of factors, such as ototoxicity, trauma, genetics, and ageing. One promising therapy is the vestibular prosthesis, which leverages the success of the cochlear implant, and endeavours to electrically integrate the primary vestibular afferents with the vestibular scene. Other translational approaches of interest include stem cell regeneration and gene therapies, which aim to restore or modify inner ear receptor function. However, both of these techniques are in their infancy and are currently undergoing further characterization and development in the laboratory, using animal models. Another promising translational avenue to treating vestibular hair cell dysfunction is the potential development of artificial biocompatible hair cell sensors, aiming to replicate functional hair cells and generate synthetic 'receptor potentials' for sensory coding of vestibular stimuli to the brain. Recently, artificial hair cell sensors have demonstrated significant promise, with improvements in their output, such as sensitivity and frequency selectivity. This article reviews the history and current state of bioelectronic devices to interface with the labyrinth, spanning the vestibular implant and artificial hair cell sensors.
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Affiliation(s)
| | - Christopher John Pastras
- School of Engineering, Macquarie University, Sydney, NSW, Australia; School of Medical Sciences, University of Sydney, NSW, Australia
| | - Rajni Sharma
- School of Engineering, Macquarie University, Sydney, NSW, Australia
| | - M A Parvez Mahmud
- School of Engineering, Deakin University, Geelong, VIC, 3216, Australia
| | - Rachel Ryan
- College of Public Health, The Ohio State University, Columbus, OH, 43210, United States
| | - Amir Razmjou
- School of Engineering, Macquarie University, Sydney, NSW, Australia; School of Engineering, Edith Cowan University, Joondalup, Perth, WA, 6027, Australia
| | - Mohsen Asadnia
- School of Engineering, Macquarie University, Sydney, NSW, Australia.
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3
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Burwood G, He WX, Fridberger A, Ren TY, Nuttall AL. Outer hair cell driven reticular lamina mechanical distortion in living cochleae. Hear Res 2022; 423:108405. [PMID: 34916081 PMCID: PMC9170269 DOI: 10.1016/j.heares.2021.108405] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/25/2021] [Accepted: 11/25/2021] [Indexed: 11/17/2022]
Abstract
Cochlear distortions afford researchers and clinicians a glimpse into the conditions and properties of inner ear signal processing mechanisms. Until recently, our examination of these distortions has been limited to measuring the vibration of the basilar membrane or recording acoustic distortion output in the ear canal. Despite its importance, the generation mechanism of cochlear distortion remains a substantial task to understand. The ability to measure the vibration of the reticular lamina in rodent models is a recent experimental advance. Surprising mechanical properties have been revealed. These properties merit both discussion in context with our current understanding of distortion, and appraisal of the significance of new interpretations of cochlear mechanics. This review focusses on some of the recent data from our research groups and discusses the implications of these data on our understanding of vocalization processing in the periphery, and their influence upon future experimental directions. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.
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Affiliation(s)
- G Burwood
- Department of Otolaryngology, Head and Neck Surgery, Oregon Health & Science University, Portland OR, United States
| | - W X He
- Department of Otolaryngology, Head and Neck Surgery, Oregon Health & Science University, Portland OR, United States
| | - A Fridberger
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - T Y Ren
- Department of Otolaryngology, Head and Neck Surgery, Oregon Health & Science University, Portland OR, United States
| | - A L Nuttall
- Department of Otolaryngology, Head and Neck Surgery, Oregon Health & Science University, Portland OR, United States.
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Jennings SG. The role of the medial olivocochlear reflex in psychophysical masking and intensity resolution in humans: a review. J Neurophysiol 2021; 125:2279-2308. [PMID: 33909513 PMCID: PMC8285664 DOI: 10.1152/jn.00672.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 03/16/2021] [Accepted: 04/02/2021] [Indexed: 02/01/2023] Open
Abstract
This review addresses the putative role of the medial olivocochlear (MOC) reflex in psychophysical masking and intensity resolution in humans. A framework for interpreting psychophysical results in terms of the expected influence of the MOC reflex is introduced. This framework is used to review the effects of a precursor or contralateral acoustic stimulation on 1) simultaneous masking of brief tones, 2) behavioral estimates of cochlear gain and frequency resolution in forward masking, 3) the buildup and decay of forward masking, and 4) measures of intensity resolution. Support, or lack thereof, for a role of the MOC reflex in psychophysical perception is discussed in terms of studies on estimates of MOC strength from otoacoustic emissions and the effects of resection of the olivocochlear bundle in patients with vestibular neurectomy. Novel, innovative approaches are needed to resolve the dissatisfying conclusion that current results are unable to definitively confirm or refute the role of the MOC reflex in masking and intensity resolution.
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Affiliation(s)
- Skyler G Jennings
- Department of Communication Sciences and Disorders, The University of Utah, Salt Lake City, Utah
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Olson ES, Strimbu CE. Cochlear mechanics: new insights from vibrometry and Optical Coherence Tomography. CURRENT OPINION IN PHYSIOLOGY 2020; 18:56-62. [PMID: 33103018 DOI: 10.1016/j.cophys.2020.08.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The cochlea is a complex biological machine that transduces sound-induced mechanical vibrations to neural signals. Hair cells within the sensory tissue of the cochlea transduce vibrations into electrical signals, and exert electromechanical feedback that enhances the passive frequency separation provided by the cochlea's traveling wave mechanics; this enhancement is termed cochlear amplification. The vibration of the sensory tissue has been studied with many techniques, and the current state of the art is optical coherence tomography (OCT). The OCT technique allows for motion of intra-organ structures to be measured in vivo at many layers within the sensory tissue, at several angles and in previously under-explored species. OCT-based observations are already impacting our understanding of hair cell excitation and cochlear amplification.
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Affiliation(s)
- Elizabeth S Olson
- Department of Otolaryngolgy Head and Neck Surgery, Vagelos College of Physicians and Surgeons, Columbia University, 630 W 168th St, New York, NY 10032.,Department Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue,New York, NY 10027
| | - C Elliott Strimbu
- Department of Otolaryngolgy Head and Neck Surgery, Vagelos College of Physicians and Surgeons, Columbia University, 630 W 168th St, New York, NY 10032
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Ni G, Pang J, Zheng Q, Xu Z, Liu B, Zhang H, Ming D. Modeling cochlear micromechanics: hypotheses and models. JOURNAL OF BIO-X RESEARCH 2019. [DOI: 10.1097/jbr.0000000000000034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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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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Guo C, Yang X, Wu JP, Guo X, He Y, Shen Z, Sun Z, Guan T, Chen F. Image-guided vibrometry system integrated with spectral- and time-domain optical coherence tomography. APPLIED OPTICS 2019; 58:1606-1613. [PMID: 30874191 DOI: 10.1364/ao.58.001606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 01/24/2019] [Indexed: 06/09/2023]
Abstract
Vibrometry using optical coherence tomography (OCT) can provide valuable information for investigating either the mechanical properties or the physiological function of biological tissues, especially the hearing organs. Real-time imaging of the measured tissues provides structure imaging and spatial guidance for and is thus highly demanded by such vibrometry. However, the traditional time-domain OCT (TD-OCT) systems, although capable of subnanometric vibrometry at large ranges of frequencies, are unable to offer an imaging speed that is high enough to acquire depth-resolved images for guidance. The spectral-domain OCT (SD-OCT) systems, although allowing image-guided vibrometry, are challenged in measuring vibration at high frequencies, particularly for scattering tissue specimens that require longer exposure time to ensure imaging and vibrometry performance. This is because of their limit in the line-scan rate of the CCD, in which the maximum resolvable frequency measured by the SD-OCT is about 1/4 of the CCD line-scan rate in practice. In the present study, we have developed a dual-mode OCT system combining both SD-OCT and TD-OCT modalities for image-guided vibrometry, as the SD-OCT can provide guiding structural images in real-time and, moreover, the TD-OCT can guarantee vibrometry at large ranges of frequencies, including high frequencies. The efficacy of the developed system in image-guided vibrometry has been experimentally demonstrated using both piezoelectric ceramic transducer (PZT) and ex vivo middle-ear samples from guinea pigs. For the vibrometry of PZT, the minimum detectable vibration amplitude was reached at ∼0.01 nm. For the vibrometry of the sound-evoked biological samples, both real-time two-dimensional imaging and subnanometric vibrometry were performed at the frequency ranging from 1 to 40 kHz. These results indicate that our dual-mode OCT system is able to act as an excellent vibrometer enabling image-guided high-frequency measurement.
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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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10
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Choi S, Sato K, Ota T, Nin F, Muramatsu S, Hibino H. Multifrequency-swept optical coherence microscopy for highspeed full-field tomographic vibrometry in biological tissues. BIOMEDICAL OPTICS EXPRESS 2017; 8:608-621. [PMID: 28270971 PMCID: PMC5330561 DOI: 10.1364/boe.8.000608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/27/2016] [Accepted: 12/29/2016] [Indexed: 05/03/2023]
Abstract
Because conventional laser Doppler vibrometry or Doppler optical coherence tomography require mechanical scanning probes that cannot simultaneously measure the wide-range dynamics of bio-tissues, a multifrequency-swept optical coherence microscopy with wide-field heterodyne detection technique was developed. A 1024 × 1024 × 2000 voxel volume was acquired with an axial resolution of ~1.8 μm and an acquisition speed of 2 s. Vibration measurements at 10 kHz were performed over a wide field of view. Wide-field tomographic vibration measurements of a mouse tympanic membrane are demonstrated to illustrate the applicability of this method to live animals.
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Affiliation(s)
- Samuel Choi
- Niigata University, Department of Electrical and Electronics Engineering, 8050 Ikarashi-2, Niigata 950-2181, Japan
- AMED-CTRST, AMED, Japan
| | - Keita Sato
- Niigata University, Department of Electrical and Electronics Engineering, 8050 Ikarashi-2, Niigata 950-2181, Japan
| | - Takeru Ota
- AMED-CTRST, AMED, Japan
- Niigata University, School of Medicine, Department of Molecular Physiology, 757 Ichibancho, Asahimachi, Niigata 951-8510, Japan
| | - Fumiaki Nin
- AMED-CTRST, AMED, Japan
- Niigata University, School of Medicine, Department of Molecular Physiology, 757 Ichibancho, Asahimachi, Niigata 951-8510, Japan
- Niigata University, Center for Transdisciplinary Research, 8050 Ikarashi-2, Niigata 950-2181, Japan
| | - Shogo Muramatsu
- Niigata University, Department of Electrical and Electronics Engineering, 8050 Ikarashi-2, Niigata 950-2181, Japan
- AMED-CTRST, AMED, Japan
| | - Hiroshi Hibino
- AMED-CTRST, AMED, Japan
- Niigata University, School of Medicine, Department of Molecular Physiology, 757 Ichibancho, Asahimachi, Niigata 951-8510, Japan
- Niigata University, Center for Transdisciplinary Research, 8050 Ikarashi-2, Niigata 950-2181, Japan
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Ramamoorthy S, Zhang Y, Petrie T, Fridberger A, Ren T, Wang R, Jacques SL, Nuttall AL. Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:25003. [PMID: 26836207 PMCID: PMC4796094 DOI: 10.1117/1.jbo.21.2.025003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/23/2015] [Indexed: 06/05/2023]
Abstract
Sound processing in the inner ear involves separation of the constituent frequencies along the length of the cochlea. Frequencies relevant to human speech (100 to 500 Hz) are processed in the apex region. Among mammals, the guinea pig cochlear apex processes similar frequencies and is thus relevant for the study of speech processing in the cochlea. However, the requirement for extensive surgery has challenged the optical accessibility of this area to investigate cochlear processing of signals without significant intrusion. A simple method is developed to provide optical access to the guinea pig cochlear apex in two directions with minimal surgery. Furthermore, all prior vibration measurements in the guinea pig apex involved opening an observation hole in the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here, this limitation is overcome by measuring the vibrations through the unopened otic capsule using phase-sensitive Fourier domain optical coherence tomography. The optically and surgically advanced method described here lays the foundation to perform minimally invasive investigation of speech-related signal processing in the cochlea.
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Affiliation(s)
- Sripriya Ramamoorthy
- Oregon Health and Science University, Oregon Hearing Research Center, Department of Otolaryngology, 3181 SW Sam Jackson Park Road, NRC 04, Portland, Oregon 97239, United States
| | - Yuan Zhang
- Oregon Health and Science University, Oregon Hearing Research Center, Department of Otolaryngology, 3181 SW Sam Jackson Park Road, NRC 04, Portland, Oregon 97239, United States
| | - Tracy Petrie
- Oregon Health and Science University, Department of Biomedical Engineering, 3303 Bond Street, Portland, Oregon 97239, United States
| | - Anders Fridberger
- Linköping University, Department of Clinical and Experimental Medicine, Cell Biology SE-58185, Linköping, Sweden
| | - Tianying Ren
- Oregon Health and Science University, Oregon Hearing Research Center, Department of Otolaryngology, 3181 SW Sam Jackson Park Road, NRC 04, Portland, Oregon 97239, United States
| | - Ruikang Wang
- University of Washington, Department of Bioengineering, William H. Foege Building, P.O. Box 355061, 3720 15th Avenue NE, Seattle, Washington 98195-5061, United States
| | - Steven L. Jacques
- Oregon Health and Science University, Department of Biomedical Engineering, 3303 Bond Street, Portland, Oregon 97239, United States
- Oregon Health and Science University, Department of Dermatology, Portland, Oregon 97239, United States
| | - Alfred L. Nuttall
- Oregon Health and Science University, Oregon Hearing Research Center, Department of Otolaryngology, 3181 SW Sam Jackson Park Road, NRC 04, Portland, Oregon 97239, United States
- University of Michigan, Kresge Hearing Research Center, Ann Arbor, Michigan 48105, United States
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12
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Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea. Proc Natl Acad Sci U S A 2015; 112:3128-33. [PMID: 25737536 DOI: 10.1073/pnas.1500038112] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric optical coherence tomography vibrometry, a technique that overcomes these limitations by providing depth-resolved displacement measurements at 200 kHz inside a 3D volume of tissue with picometer sensitivity. We studied the mouse cochlea by imaging noninvasively through the surrounding bone to measure sound-induced vibrations of the sensory structures in vivo, and report, to our knowledge, the first measures of tectorial membrane vibration within the unopened cochlea. We found that the tectorial membrane sustains traveling wave propagation. Compared with basilar membrane traveling waves, tectorial membrane traveling waves have larger dynamic ranges, sharper frequency tuning, and apically shifted positions of peak vibration. These findings explain discrepancies between previously published basilar membrane vibration and auditory nerve single unit data. Because the tectorial membrane directly overlies the inner hair cell stereociliary bundles, these data provide the most accurate characterization of the stimulus shaping the afferent auditory response available to date.
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Gao SS, Raphael PD, Wang R, Park J, Xia A, Applegate BE, Oghalai JS. In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2013. [PMID: 23411442 DOI: 10.1364/boe.4.000230] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Sound transduction within the auditory portion of the inner ear, the cochlea, is a complex nonlinear process. The study of cochlear mechanics in large rodents has provided important insights into cochlear function. However, technological and experimental limitations have restricted studies in mice due to their smaller cochlea. These challenges are important to overcome because of the wide variety of transgenic mouse strains with hearing loss mutations that are available for study. To accomplish this goal, we used spectral domain optical coherence tomography to visualize and measure sound-induced vibrations of intracochlear tissues. We present, to our knowledge, the first vibration measurements from the apex of an unopened mouse cochlea.
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Affiliation(s)
- Simon S Gao
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA ; Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
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14
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Gao SS, Raphael PD, Wang R, Park J, Xia A, Applegate BE, Oghalai JS. In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2013; 4:230-40. [PMID: 23411442 PMCID: PMC3567710 DOI: 10.1364/boe.4.00230] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 01/11/2013] [Accepted: 01/14/2013] [Indexed: 05/03/2023]
Abstract
Sound transduction within the auditory portion of the inner ear, the cochlea, is a complex nonlinear process. The study of cochlear mechanics in large rodents has provided important insights into cochlear function. However, technological and experimental limitations have restricted studies in mice due to their smaller cochlea. These challenges are important to overcome because of the wide variety of transgenic mouse strains with hearing loss mutations that are available for study. To accomplish this goal, we used spectral domain optical coherence tomography to visualize and measure sound-induced vibrations of intracochlear tissues. We present, to our knowledge, the first vibration measurements from the apex of an unopened mouse cochlea.
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Affiliation(s)
- Simon S. Gao
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Patrick D. Raphael
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA
| | - Rosalie Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA
| | - Jesung Park
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843, USA
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA
| | - Brian E. Applegate
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843, USA
| | - John S. Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
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