The Tectorial Membrane of the Rat'
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Reticular Lamina and Basilar Membrane Vibrations in Living Mouse Cochleae
Reticular lamina and basilar membrane vibrations in living mouse cochleae Tianying Rena,1, Wenxuan Hea, and David Kempb aOregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, OR 97239; and bUniversity College London Ear Institute, University College London, London WC1E 6BT, United Kingdom Edited by Mario A. Ruggero, Northwestern University, Evanston, IL, and accepted by Editorial Board Member Peter L. Strick July 1, 2016 (received for review May 9, 2016) It is commonly believed that the exceptional sensitivity of mamma- (Fig. 1 A and B and Materials and Methods). The results from this lian hearing depends on outer hair cells which generate forces for study do not demonstrate the commonly expected cochlear local amplifying sound-induced basilar membrane vibrations, yet how feedback but instead indicate a global hydromechanical mecha- cellular forces amplify vibrations is poorly understood. In this study, nism for outer hair cells to enhance hearing sensitivity. by measuring subnanometer vibrations directly from the reticular lamina at the apical ends of outer hair cells and from the basilar Results membrane using a custom-built heterodyne low-coherence interfer- Vibrations of the Reticular Lamina and Basilar Membrane in Sensitive ometer, we demonstrate in living mouse cochleae that the sound- Cochleae. Vibrations of the reticular lamina and basilar membrane induced reticular lamina vibration is substantially larger than the measured from a sensitive cochlea are presented in Fig. 1 C–J. basilar membrane vibration not only at the best frequency but Below 50 dB sound pressure level (SPL) (0 dB SPL = 20 μPa), the surprisingly also at low frequencies. -
Sound and the Ear Chapter 2
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chapter© Jones & Bartlett 2 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Sound and the Ear © Jones Karen &J. Kushla,Bartlett ScD, Learning, CCC-A, FAAA LLC © Jones & Bartlett Learning, LLC Lecturer NOT School FOR of SALE Communication OR DISTRIBUTION Disorders and Deafness NOT FOR SALE OR DISTRIBUTION Kean University © Jones & Bartlett Key Learning, Terms LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR Acceleration DISTRIBUTION Incus NOT FOR SALE OR Saccule DISTRIBUTION Acoustics Inertia Scala media Auditory labyrinth Inner hair cells Scala tympani Basilar membrane Linear scale Scala vestibuli Bel Logarithmic scale Semicircular canals Boyle’s law Malleus Sensorineural hearing loss Broca’s area © Jones & Bartlett Mass Learning, LLC Simple harmonic© Jones motion (SHM) & Bartlett Learning, LLC Brownian motion Membranous labyrinth Sound Cochlea NOT FOR SALE OR Mixed DISTRIBUTION hearing loss Stapedius muscleNOT FOR SALE OR DISTRIBUTION Compression Organ of Corti Stapes Condensation Osseous labyrinth Tectorial membrane Conductive hearing loss Ossicular chain Tensor tympani muscle Decibel (dB) Ossicles Tonotopic organization © Jones Decibel & hearing Bartlett level (dB Learning, HL) LLC Outer ear © Jones Transducer & Bartlett Learning, LLC Decibel sensation level (dB SL) Outer hair cells Traveling wave theory NOT Decibel FOR sound SALE pressure OR level DISTRIBUTION -
Mathematical Model of the Cupula-Endolymph System with Morphological Parameters for the Axolotl (Ambystoma Tigrinum) Semicircular Canals
138 The Open Medical Informatics Journal, 2008, 2, 138-148 Open Access Mathematical Model of the Cupula-Endolymph System with Morphological Parameters for the Axolotl (Ambystoma tigrinum) Semicircular Canals Rosario Vega1, Vladimir V. Alexandrov2,3, Tamara B. Alexandrova1,3 and Enrique Soto*,1 1Instituto de Fisiología, Universidad Autónoma de Puebla, 2Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Puebla, 3 Lomonosov Moscow State University, Mexico Abstract: By combining mathematical methods with the morphological analysis of the semicircular canals of the axolotl (Ambystoma tigrinum), a system of differential equations describing the mechanical coupling in the semicircular canals was obtained. The coefficients of this system have an explicit physiological meaning that allows for the introduction of morphological and dynamical parameters directly into the differential equations. The cupula of the semicircular canals was modeled both as a piston and as a membrane (diaphragm like), and the duct canals as toroids with two main regions: i) the semicircular canal duct and, ii) a larger diameter region corresponding to the ampulla and the utricle. The endolymph motion was described by the Navier-Stokes equations. The analysis of the model demonstrated that cupular behavior dynamics under periodic stimulation is equivalent in both the piston and the membrane cupular models, thus a general model in which the detailed cupular structure is not relevant was derived. Keywords: Inner ear, vestibular, hair cell, transduction, sensory coding, physiology. 1. INTRODUCTION linear acceleration detectors, and the SCs as angular accel- eration detectors, notwithstanding that both sensory organs The processing of sensory information in the semicircular are based on a very similar sensory cell type. -
Vibration Hotspots Reveal Longitudinal Funneling of Sound-Evoked Motion in the Mammalian Cochlea
ARTICLE DOI: 10.1038/s41467-018-05483-z OPEN Vibration hotspots reveal longitudinal funneling of sound-evoked motion in the mammalian cochlea Nigel P. Cooper 1, Anna Vavakou1 & Marcel van der Heijden 1 The micromechanical mechanisms that underpin tuning and dynamic range compression in the mammalian inner ear are fundamental to hearing, but poorly understood. Here, we present new, high-resolution optical measurements that directly map sound-evoked vibra- 1234567890():,; tions on to anatomical structures in the intact, living gerbil cochlea. The largest vibrations occur in a tightly delineated hotspot centering near the interface between the Deiters’ and outer hair cells. Hotspot vibrations are less sharply tuned, but more nonlinear, than basilar membrane vibrations, and behave non-monotonically (exhibiting hyper-compression) near their characteristic frequency. Amplitude and phase differences between hotspot and basilar membrane responses depend on both frequency and measurement angle, and indicate that hotspot vibrations involve longitudinal motion. We hypothesize that structural coupling between the Deiters’ and outer hair cells funnels sound-evoked motion into the hotspot region, under the control of the outer hair cells, to optimize cochlear tuning and compression. 1 Department of Neuroscience, Erasmus MC, Room Ee 1285, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. Correspondence and requests for materials should be addressed to M.v.d.H. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:3054 | DOI: 10.1038/s41467-018-05483-z -
ANATOMY of EAR Basic Ear Anatomy
ANATOMY OF EAR Basic Ear Anatomy • Expected outcomes • To understand the hearing mechanism • To be able to identify the structures of the ear Development of Ear 1. Pinna develops from 1st & 2nd Branchial arch (Hillocks of His). Starts at 6 Weeks & is complete by 20 weeks. 2. E.A.M. develops from dorsal end of 1st branchial arch starting at 6-8 weeks and is complete by 28 weeks. 3. Middle Ear development —Malleus & Incus develop between 6-8 weeks from 1st & 2nd branchial arch. Branchial arches & Development of Ear Dev. contd---- • T.M at 28 weeks from all 3 germinal layers . • Foot plate of stapes develops from otic capsule b/w 6- 8 weeks. • Inner ear develops from otic capsule starting at 5 weeks & is complete by 25 weeks. • Development of external/middle/inner ear is independent of each other. Development of ear External Ear • It consists of - Pinna and External auditory meatus. Pinna • It is made up of fibro elastic cartilage covered by skin and connected to the surrounding parts by ligaments and muscles. • Various landmarks on the pinna are helix, antihelix, lobule, tragus, concha, scaphoid fossa and triangular fossa • Pinna has two surfaces i.e. medial or cranial surface and a lateral surface . • Cymba concha lies between crus helix and crus antihelix. It is an important landmark for mastoid antrum. Anatomy of external ear • Landmarks of pinna Anatomy of external ear • Bat-Ear is the most common congenital anomaly of pinna in which antihelix has not developed and excessive conchal cartilage is present. • Corrections of Pinna defects are done at 6 years of age. -
Special Ear Problem (Worksheet)
Special Ear Problem (Worksheet) anvil hammer oval window Extenal auditory canal Cochlea Ear drum stirrip organ of corti Round window Basilar membrane A) Label on the drawing above: 1. External auditory canal 2. ear drum (tympanic membrane) 3. hammer (maleus) 4. anvil (incus) 5. stirrup (stapes) 6. cochlea 7. oval window 8. round window 9. basilar membrane 10. organ of Corti B) In one or two sentences, what is the function of the outer ear The outer ear collects sound and guides it to the eardrum. C) The external auditory canal functions like a 2.5 cm closed pipe. What are the first two resonances of this pipe and how do these explain features of Figure 12-7 on page 354 of your book (Giancoli)? The first two resonances are about 3500 Hz --- the frequency where your ear is most sensitive --- and 10,5000 --- which corresponds to kinks in the curves of Fig. 12-7. D)What is the boundary between the outer ear and the middle ear? The Eardrum E) In one or two sentences, what is the function of the middle ear? The middle ear takes the pressure wave coming from the (large area) eardrum and “amplifies” the pressure by about 40 to generate a wave in the fluid of the cochlea through the (small area) oval window. F) What is the boundary between the middle ear and the inner ear? The oval window. G) In one or two sentences, what is the function of the inner ear? The inner ear generates electrical signals from the (liquid) pressure waves generated at the oval window. -
Endolymphatic Hydrops Meniere's
ENDOLYMPHATIC HYDROPS MENIERE’S DISEASE Introduction: Meniere’s Disease, or endolymphatic hydrops, is a disorder of the inner ear. This condition occurs because of abnormal fluctuations in the inner ear fluid called endolymph. A system of membranes, called the membranous labyrinth, contains a fluid called endolymph. This fluid bathes the inner ear balance and hearing system sensory cells and allows them to function normally. The membranes can become dilated like a balloon when pressure increases. This is called "hydrops". The amount of fluid is normally kept constant by altering the production and absorption of the fluid. Endolymph also contains a specific concentration of sodium, potassium, chloride, and other electrolytes. If the inner ear is damaged by disease, injury, or other causes, the volume and composition of the inner ear fluid can fluctuate with changes in the body’s fluid and electrolyte levels. This fluctuation in inner ear fluid can cause the symptoms of hydrops, including pressure or fullness of the affected ear, tinnitus, hearing loss, and imbalance or dizziness. Treatment of this condition is geared towards stabilizing the body fluid levels so that fluctuations in the endolymph volume can be avoided. Meniere's episodes may occur in clusters in which several attacks may occur within a short period of time. On the other hand, years may pass between episodes. Between the acute attacks, most people are free of symptoms or note mild imbalance, tinnitus, and/or hearing loss. Meniere’s affects roughly 0.2% of the population, about 200 out of 100,000 people (or in other words, 2/1000). -
36 | Sensory Systems 1109 36 | SENSORY SYSTEMS
Chapter 36 | Sensory Systems 1109 36 | SENSORY SYSTEMS Figure 36.1 This shark uses its senses of sight, vibration (lateral-line system), and smell to hunt, but it also relies on its ability to sense the electric fields of prey, a sense not present in most land animals. (credit: modification of work by Hermanus Backpackers Hostel, South Africa) Chapter Outline 36.1: Sensory Processes 36.2: Somatosensation 36.3: Taste and Smell 36.4: Hearing and Vestibular Sensation 36.5: Vision Introduction In more advanced animals, the senses are constantly at work, making the animal aware of stimuli—such as light, or sound, or the presence of a chemical substance in the external environment—and monitoring information about the organism’s internal environment. All bilaterally symmetric animals have a sensory system, and the development of any species’ sensory system has been driven by natural selection; thus, sensory systems differ among species according to the demands of their environments. The shark, unlike most fish predators, is electrosensitive—that is, sensitive to electrical fields produced by other animals in its environment. While it is helpful to this underwater predator, electrosensitivity is a sense not found in most land animals. 36.1 | Sensory Processes By the end of this section, you will be able to do the following: • Identify the general and special senses in humans • Describe three important steps in sensory perception • Explain the concept of just-noticeable difference in sensory perception Senses provide information about the body and its environment. Humans have five special senses: olfaction (smell), gustation (taste), equilibrium (balance and body position), vision, and hearing. -
The Role of Potassium Recirculation in Cochlear Amplification
The role of potassium recirculation in cochlear amplification Pavel Mistrika and Jonathan Ashmorea,b aUCL Ear Institute and bDepartment of Neuroscience, Purpose of review Physiology and Pharmacology, UCL, London, UK Normal cochlear function depends on maintaining the correct ionic environment for the Correspondence to Jonathan Ashmore, Department of sensory hair cells. Here we review recent literature on the cellular distribution of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London WC1E 6BT, UK potassium transport-related molecules in the cochlea. Tel: +44 20 7679 8937; fax: +44 20 7679 8990; Recent findings e-mail: [email protected] Transgenic animal models have identified novel molecules essential for normal hearing Current Opinion in Otolaryngology & Head and and support the idea that potassium is recycled in the cochlea. The findings indicate that Neck Surgery 2009, 17:394–399 extracellular potassium released by outer hair cells into the space of Nuel is taken up by supporting cells, that the gap junction system in the organ of Corti is involved in potassium handling in the cochlea, that the gap junction system in stria vascularis is essential for the generation of the endocochlear potential, and that computational models can assist in the interpretation of the systems biology of hearing and integrate the molecular, electrical, and mechanical networks of the cochlear partition. Such models suggest that outer hair cell electromotility can amplify over a much broader frequency range than expected from isolated cell studies. Summary These new findings clarify the role of endolymphatic potassium in normal cochlear function. They also help current understanding of the mechanisms of certain forms of hereditary hearing loss. -
Anatomy of the Ear ANATOMY & Glossary of Terms
Anatomy of the Ear ANATOMY & Glossary of Terms By Vestibular Disorders Association HEARING & ANATOMY BALANCE The human inner ear contains two divisions: the hearing (auditory) The human ear contains component—the cochlea, and a balance (vestibular) component—the two components: auditory peripheral vestibular system. Peripheral in this context refers to (cochlea) & balance a system that is outside of the central nervous system (brain and (vestibular). brainstem). The peripheral vestibular system sends information to the brain and brainstem. The vestibular system in each ear consists of a complex series of passageways and chambers within the bony skull. Within these ARTICLE passageways are tubes (semicircular canals), and sacs (a utricle and saccule), filled with a fluid called endolymph. Around the outside of the tubes and sacs is a different fluid called perilymph. Both of these fluids are of precise chemical compositions, and they are different. The mechanism that regulates the amount and composition of these fluids is 04 important to the proper functioning of the inner ear. Each of the semicircular canals is located in a different spatial plane. They are located at right angles to each other and to those in the ear on the opposite side of the head. At the base of each canal is a swelling DID THIS ARTICLE (ampulla) and within each ampulla is a sensory receptor (cupula). HELP YOU? MOVEMENT AND BALANCE SUPPORT VEDA @ VESTIBULAR.ORG With head movement in the plane or angle in which a canal is positioned, the endo-lymphatic fluid within that canal, because of inertia, lags behind. When this fluid lags behind, the sensory receptor within the canal is bent. -
Ultrastructural Analysis and ABR Alterations in the Cochlear Hair-Cells Following Aminoglycosides Administration in Guinea Pig
Global Journal of Otolaryngology ISSN 2474-7556 Research Article Glob J Otolaryngol Volume 15 Issue 4 - May 2018 Copyright © All rights are reserved by Mohammed A Akeel DOI: 10.19080/GJO.2018.15.555916 Ultrastructural Analysis and ABR Alterations in the Cochlear Hair-cells Following Aminoglycosides Administration in Guinea Pig Mohammed A Akeel* Department of Anatomy, Faculty of Medicine, Jazan University, Jazan, Kingdom of Saudi Arabia Submission: April 18, 2018; Published: May 08, 2018 *Corresponding author: Mohammed A Akeel, Faculty of Medicine, Jazan University, P.O.Box 114, Jazan, Kingdom of Saudi Arabia. Tel: ; Email: Abstract Aims: since their introduction in the 1940. The aim of the present work was to characterize ultrastructural alterations of the sensory hair-cell following different aminoglycosides Aminoglycosides administration, (AG) antibiotics intratympanic were the first VS ototoxic intraperitoneal agents to and highlight to correlate the problem them with of drug-induced auditory brainstem hearing responses and vestibular (ABR). loss, Methods: streptomycin, gentamycin, or netilmicin; respectively, via the peritoneal route. The next four groups received similar treatment via trans- tympanic route. A Thetotal treatment of 48 adult was guinea administered pigs were dividedfor seven into consecutive 8 groups; sixdays. animals On day in 10,each ABR group. was The utilized first fourfor hearing groups receivedevaluation saline and (control),scanning electron microscopy (SEM) examination of the sensory organs was used for morphological study. Results: Streptomycin produced the most severe morphological changes and a higher elevation of ABR thresholds, followed, in order, by gentamycin and netilmicin. Netilmicin ototoxicity observed in both systemic and transtympanic routes was low because of lesser penetration into the inner ear or/ and lower intrinsic toxicity. -
Development of the Organ of Corti Appears to Be Separated Into 2496 P
Development 129, 2495-2505 (2002) 2495 Printed in Great Britain © The Company of Biologists Limited 2002 DEV1807 The role of Math1 in inner ear development: Uncoupling the establishment of the sensory primordium from hair cell fate determination Ping Chen1,*, Jane E. Johnson2, Huda Y. Zoghbi3 and Neil Segil1,4,* 1Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, CA 90057, USA 2Center for Basic Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA 3Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA 4Department of Cell and Neurobiology, University of Southern California Medical School, Los Angeles, CA 90033, USA *Authors for correspondence (e-mail: [email protected] and [email protected]) Accepted 5 March 2002 SUMMARY During embryonic development of the inner ear, the anlage. The expression of Math1 is limited to a sensory primordium that gives rise to the organ of Corti subpopulation of cells within the sensory primordium that from within the cochlear epithelium is patterned into a appear to differentiate exclusively into hair cells as the stereotyped array of inner and outer sensory hair cells sensory epithelium matures and elongates through a separated from each other by non-sensory supporting cells. process that probably involves radial intercalation of cells. Math1, a close homolog of the Drosophila proneural gene Furthermore, mutation of Math1 does not affect the atonal, has been found to be both necessary and sufficient establishment of this postmitotic sensory primordium, even for the production of hair cells in the mouse inner ear.