Pathway of Sound and Components of the Ear Frequency Selectivity Of
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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 -
Activity-Dependent Regulation of Prestin Expression in Mouse Outer Hair Cells
J Neurophysiol 113: 3531–3542, 2015. First published March 25, 2015; doi:10.1152/jn.00869.2014. Activity-dependent regulation of prestin expression in mouse outer hair cells Yohan Song, Anping Xia, Hee Yoon Lee, Rosalie Wang, Anthony J. Ricci, and John S. Oghalai Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California Submitted 4 November 2014; accepted in final form 19 March 2015 Song Y, Xia A, Lee HY, Wang R, Ricci AJ, Oghalai JS. patch-clamp recording conditions (Kakehata and Santos-Sac- Activity-dependent regulation of prestin expression in mouse outer chi, 1995 and 1996; Santos-Sacchi 1991; Santos-Sacchi et al. hair cells. J Neurophysiol 113: 3531–3542, 2015. First published 1998a). Thus, measuring the NLC is a common way of assess- March 25, 2015; doi:10.1152/jn.00869.2014.—Prestin is a membrane protein necessary for outer hair cell (OHC) electromotility and normal ing the amount of functional prestin within an OHC (Abe et al. 2007; Oliver and Fakler 1999;). hearing. Its regulatory mechanisms are unknown. Several mouse Downloaded from models of hearing loss demonstrate increased prestin, inspiring us to There are many ways to modulate the voltage dependence of investigate how hearing loss might feedback onto OHCs. To test force production by prestin protein within the plasma mem- whether centrally mediated feedback regulates prestin, we developed brane, such as changing the surrounding lipid environment, a novel model of inner hair cell loss. Injection of diphtheria toxin (DT) intracellular Ca2ϩ level, membrane tension, membrane poten- into adult CBA mice produced significant loss of inner hair cells tial, and ionic composition of the intracellular and extracellular without affecting OHCs. -
Introduction to Sound and Hearing
Salamanca Study Abroad Program: Neurobiology of Hearing Cochlear mechanics R. Keith Duncan University of Michigan [email protected] Outline Passive and active cochlear mechanics Prestin and outer hair cell motility Tonotopicity A place code is a general principle of many sensory systems (somatotopic, retinotopic, others?) Damage (hair cell loss) at particular locations along the cochlea is correlated with hearing loss at a particular frequency. The place code in the cochlea is “tonotopic”, each sound frequency stimulating a particular location best. Cochlear place is “tuned” to particular frequencies. But how is this frequency “tuning” established? Era of the “traveling wave” begins 1 kHz Georg von Békésy (1899-1972) Awarded a Nobel prize in 1961 for studies on cochlear mechanics. See “Experiments in hearing” compiled by Glen Weaver. “in situ” measurements • Improve visualization with silver grains and strobe illumination • Measure amp. of motion for constant input pressure at various frequencies. Tonotopic Distribution of Frequency The cochlea is a frequency analyzer, breaking complex waves into frequency components. Tonos = tone; Topia = place Tonotopic = frequency place code 4 kHz 1 kHz 250 Hz Passive mechanics largely due to gradual changes in the stiffness of the basilar membrane. Base: thick and narrow Apex: thin and wide A (Nonlinear) Amplifier in the Ear Gain = Amplitude of basilar membrane Amplitude of stapes motion Use laser to measure membrane at one tonotopic position. Compare with stapes motion to get gain. Vary frequency of sound stimulus while keeping input (stapes motion) constant. Passive mechanics gives the “dead or high level shape” (like with Békésy). Something else happens at low sound levels in an alive animal (like with psychoacoustics). -
The Underwater Piano: a Resonance Theory of Cochlear Mechanics
The Underwater Piano: A Resonance Theory of Cochlear Mechanics by James Andrew Bell A thesis submitted for the degree of Doctor of Philosophy of The Australian National University July 2005 Visual Sciences Group Research School of Biological Sciences The Australian National University Canberra, ACT 0200 Australia This thesis is my original work and has not been submitted, in whole or in part, for a degree at this or any other university. Nor does it contain, to the best of my knowledge and belief, any material published or written by any other person, except as acknowledged in the text. In particular, I acknowledge the contribution of Professor Neville H. Fletcher who wrote Appendix A of Bell & Fletcher (2004) [§R 5.6 in this thesis] and who helped refine the text of that paper. Dr Ted Maddess provided the draft Matlab code used to perform the autocorrelation analysis reported in Chapter R7. Sharyn Wragg, RSBS Illustrator, drew some of the figures as noted. Signed: ……………………………………………… Date: ………………………………………………… Acknowledgements This thesis would not have appeared without the encouragement, support, and interest of many people. Yet, among them, the primary mainstay of this enterprise has been my wife, Libby, who has stayed by me on this long journey. I thank her for understanding and tolerance. Rachel, Sarah, Micah, Adam, Daniel, and Joshua have given their love and support, too, and that has been a source of strength. My supervisors have contributed in large measure, and I am grateful to all of them. Professor Anthony W. Gummer of the University of Tübingen saw the potential of this work at an early stage, and I thank him for his initiative in opening the door to this PhD study and providing some support (a grant from the German Research Council, SFB 430, to A.W. -
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 Tectorial Membrane of the Rat'
The Tectorial Membrane of the Rat’ MURIEL D. ROSS Department of Anatomy, The University of Michigan, Ann Arbor, Michigan 48104 ABSTRACT Histochemical, x-ray analytical and scanning and transmission electron microscopical procedures have been utilized to determine the chemical nature, physical appearance and attachments of the tectorial membrane in nor- mal rats and to correlate these results with biochemical data on protein-carbo- hydrate complexes. Additionally, pertinent histochemical and ultrastructural findings in chemically sympathectomized rats are considered. The results indi- cate that the tectorial membrane is a viscous, complex, colloid of glycoprotein( s) possessing some oriented molecules and an ionic composition different from either endolymph or perilymph. It is attached to the reticular laminar surface of the organ of Corti and to the tips of the outer hair cells; it is attached to and encloses the hairs of the inner hair cells. A fluid compartment may exist within the limbs of the “W’formed by the hairs on each outer hair cell surface. Present biochemical concepts of viscous glycoproteins suggest that they are polyelectro- lytes interacting physically to form complex networks. They possess character- istics making them important in fluid and ion transport. Furthermore, the macro- molecular configuration assumed by such polyelectrolytes is unstable and subject to change from stress or shifts in pH or ions. Thus, the attachments of the tec- torial membrane to the hair cells may play an important role in the transduction process at the molecular level. The present investigation is an out- of the tectorial membrane remain matters growth of a prior study of the effects of of dispute. -
A Role for Tectorial Membrane Mechanics in Activating the Cochlear Amplifer Amir Nankali1, Yi Wang4, Clark Elliott Strimbu4, Elizabeth S
www.nature.com/scientificreports OPEN A role for tectorial membrane mechanics in activating the cochlear amplifer Amir Nankali1, Yi Wang4, Clark Elliott Strimbu4, Elizabeth S. Olson3,4 & Karl Grosh1,2* The mechanical and electrical responses of the mammalian cochlea to acoustic stimuli are nonlinear and highly tuned in frequency. This is due to the electromechanical properties of cochlear outer hair cells (OHCs). At each location along the cochlear spiral, the OHCs mediate an active process in which the sensory tissue motion is enhanced at frequencies close to the most sensitive frequency (called the characteristic frequency, CF). Previous experimental results showed an approximate 0.3 cycle phase shift in the OHC-generated extracellular voltage relative the basilar membrane displacement, which was initiated at a frequency approximately one-half octave lower than the CF. Findings in the present paper reinforce that result. This shift is signifcant because it brings the phase of the OHC-derived electromotile force near to that of the basilar membrane velocity at frequencies above the shift, thereby enabling the transfer of electrical to mechanical power at the basilar membrane. In order to seek a candidate physical mechanism for this phenomenon, we used a comprehensive electromechanical mathematical model of the cochlear response to sound. The model predicts the phase shift in the extracellular voltage referenced to the basilar membrane at a frequency approximately one-half octave below CF, in accordance with the experimental data. In the model, this feature arises from a minimum in the radial impedance of the tectorial membrane and its limbal attachment. These experimental and theoretical results are consistent with the hypothesis that a tectorial membrane resonance introduces the correct phasing between mechanical and electrical responses for power generation, efectively turning on the cochlear amplifer. -
Prestin Is the Motor Protein of Cochlear Outer Hair Cells
articles Prestin is the motor protein of cochlear outer hair cells Jing Zheng*, Weixing Shen*, David Z. Z. He*, Kevin B. Long², Laird D. Madison² & Peter Dallos* * Auditory Physiology Laboratory (The Hugh Knowles Center), Departments of Neurobiology and Physiology and Communciation Sciences and Disorders, Northwestern University, Evanston, Illinois 60208, USA ² Center for Endocrinology, Metabolism, and Molecular Medicine, Department of Medicine, Northwestern University Medical School, Chicago, Illinois 60611, USA ............................................................................................................................................................................................................................................................................ The outer and inner hair cells of the mammalian cochlea perform different functions. In response to changes in membrane potential, the cylindrical outer hair cell rapidly alters its length and stiffness. These mechanical changes, driven by putative molecular motors, are assumed to produce ampli®cation of vibrations in the cochlea that are transduced by inner hair cells. Here we have identi®ed an abundant complementary DNA from a gene, designated Prestin, which is speci®cally expressed in outer hair cells. Regions of the encoded protein show moderate sequence similarity to pendrin and related sulphate/anion transport proteins. Voltage-induced shape changes can be elicited in cultured human kidney cells that express prestin. The mechanical response of outer hair cells -
Cochlear Outer Hair Cell Motility
Physiol Rev 88: 173–210, 2008; doi:10.1152/physrev.00044.2006. Cochlear Outer Hair Cell Motility JONATHAN ASHMORE Department of Physiology and UCL Ear Institute, University College London, London, United Kingdom I. Introduction 174 II. Auditory Physiology and Cochlear Mechanics 174 A. The cochlea as a frequency analyzer 175 B. Cochlear bandwidths and models 175 C. Physics of cochlear amplification 177 D. Cellular origin of cochlear amplification 177 Downloaded from E. OHCs change length 178 F. Speed of OHC length changes 178 G. Strains and stresses of OHC motility 179 III. Cellular Mechanisms of Outer Hair Cell Motility 181 A. OHC motility is determined by membrane potential 182 B. OHC motility depends on the lateral plasma membrane 182 C. OHC motility as a piezoelectric phenomenon 183 physrev.physiology.org D. Charge movement and membrane capacitance in OHCs 184 E. Tension sensitivity of the membrane charge movement 185 F. Mathematical models of OHC motility 186 IV. Molecular Basis of Motility 186 A. The motor molecule as an area motor 186 B. Biophysical considerations 187 C. The candidate motor molecule: prestin (SLC26A5) 187 D. Prestin knockout mice and the cochlear amplifier 188 E. Genetics of prestin 188 on February 28, 2012 F. Prestin as an incomplete transporter 189 G. Structure of prestin 190 H. Function of the hydrophobic core of prestin 190 I. Function of the terminal ends of prestin 191 J. A model for prestin 191 V. Specialized Properties of the Outer Hair Cell Basolateral Membrane 192 A. Density of the motor protein 192 B. Cochlear development and the motor protein 193 C. -
VESTIBULAR SYSTEM (Balance/Equilibrium) the Vestibular Stimulus Is Provided by Earth's Gravity, and Head/Body Movement. Locate
VESTIBULAR SYSTEM (Balance/Equilibrium) The vestibular stimulus is provided by Earth’s gravity, and head/body movement. Located in the labyrinths of the inner ear, in two components: 1. Vestibular sacs - gravity & head direction 2. Semicircular canals - angular acceleration (changes in the rotation of the head, not steady rotation) 1. Vestibular sacs (Otolith organs) - made of: a) Utricle (“little pouch”) b) Saccule (“little sac”) Signaling mechanism of Vestibular sacs Receptive organ located on the “floor” of Utricle and on “wall” of Saccule when head is in upright position - crystals move within gelatinous mass upon head movement; - crystals slightly bend cilia of hair cells also located within gelatinous mass; - this increases or decreases rate of action potentials in bipolar vestibular sensory neurons. Otoconia: Calcium carbonate crystals Gelatinous mass Cilia Hair cells Vestibular nerve Vestibular ganglion 2. Semicircular canals: 3 ring structures; each filled with fluid, separated by a membrane. Signaling mechanism of Semicircular canals -head movement induces movement of endolymph, but inertial resistance of endolymph slightly bends cupula (endolymph movement is initially slower than head mvmt); - cupula bending slightly moves the cilia of hair cells; - this bending changes rate of action potentials in bipolar vestibular sensory neurons; - when head movement stops: endolymph movement continues for slightly longer, again bending the cupula but in reverse direction on hair cells which changes rate of APs; - detects “acceleration” -
Anatomic Moment
Anatomic Moment Hearing, I: The Cochlea David L. Daniels, Joel D. Swartz, H. Ric Harnsberger, John L. Ulmer, Katherine A. Shaffer, and Leighton Mark The purpose of the ear is to transform me- cochlear recess, which lies on the medial wall of chanical energy (sound) into electric energy. the vestibule (Fig 3). As these sound waves The external ear collects and directs the sound. enter the perilymph of the scala vestibuli, they The middle ear converts the sound to fluid mo- are transmitted through the vestibular mem- tion. The inner ear, specifically the cochlea, brane into the endolymph of the cochlear duct, transforms fluid motion into electric energy. causing displacement of the basilar membrane, The cochlea is a coiled structure consisting of which stimulates the hair cell receptors of the two and three quarter turns (Figs 1 and 2). If it organ of Corti (Figs 4–7) (4, 5). It is the move- were elongated, the cochlea would be approxi- ment of hair cells that generates the electric mately 30 mm in length. The fluid-filled spaces potentials that are converted into action poten- of the cochlea are comprised of three parallel tials in the auditory nerve fibers. The basilar canals: an outer scala vestibuli (ascending spi- membrane varies in width and tension from ral), an inner scala tympani (descending spi- base to apex. As a result, different portions of ral), and the central cochlear duct (scala media) the membrane respond to different auditory fre- (1–7). The scala vestibuli and scala tympani quencies (2, 5). These perilymphatic waves are contain perilymph, a substance similar in com- transmitted via the apex of the cochlea (helico- position to cerebrospinal fluid. -
The Nervous System: General and Special Senses
18 The Nervous System: General and Special Senses PowerPoint® Lecture Presentations prepared by Steven Bassett Southeast Community College Lincoln, Nebraska © 2012 Pearson Education, Inc. Introduction • Sensory information arrives at the CNS • Information is “picked up” by sensory receptors • Sensory receptors are the interface between the nervous system and the internal and external environment • General senses • Refers to temperature, pain, touch, pressure, vibration, and proprioception • Special senses • Refers to smell, taste, balance, hearing, and vision © 2012 Pearson Education, Inc. Receptors • Receptors and Receptive Fields • Free nerve endings are the simplest receptors • These respond to a variety of stimuli • Receptors of the retina (for example) are very specific and only respond to light • Receptive fields • Large receptive fields have receptors spread far apart, which makes it difficult to localize a stimulus • Small receptive fields have receptors close together, which makes it easy to localize a stimulus. © 2012 Pearson Education, Inc. Figure 18.1 Receptors and Receptive Fields Receptive Receptive field 1 field 2 Receptive fields © 2012 Pearson Education, Inc. Receptors • Interpretation of Sensory Information • Information is relayed from the receptor to a specific neuron in the CNS • The connection between a receptor and a neuron is called a labeled line • Each labeled line transmits its own specific sensation © 2012 Pearson Education, Inc. Interpretation of Sensory Information • Classification of Receptors • Tonic receptors