DOCSLIB.ORG

Frequency-Dependent Responses Exhibited by Multiple Regions in Human Auditory Cortex1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Frequency-Dependent Responses Exhibited by Multiple Regions in Human Auditory Cortex1 Hearing Research 150 (2000) 225^244 www.elsevier.com/locate/heares Frequency-dependent responses exhibited by multiple regions in human auditory cortex1 Thomas M. Talavage a;b;*, Patrick J. Ledden b, Randall R. Benson b;2, Bruce R. Rosen b, Jennifer R. Melcher a;c;d; a Speech and Hearing Sciences Program, MIT-Harvard Division of Health Sciences and Technology, Cambridge, MA, USA b MGH-NMR Center, Department of Radiology, Massachusetts General Hospital, Building 149, 13th Street (2301), Charlestown, Boston, MA 02129, USA c Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA d Department of Otolaryngology, Eaton-Peabody Laboratory, Massachusetts Eye and Ear In¢rmary, Boston, MA 02114, USA Received 3 July 1999; accepted 29 August 2000 Abstract Recordings in experimental animals have detailed the tonotopic organization of auditory cortex, including the presence of multiple tonotopic maps. In contrast, relatively little is known about tonotopy within human auditory cortex, for which even the number and location of tonotopic maps remains unclear. The present study begins to develop a more complete picture of cortical tonotopic organization in humans using functional magnetic resonance imaging, a technique that enables the non-invasive localization of neural activity in the brain. Subjects were imaged while listening to lower- (below 660 Hz) and higher- (above 2490 Hz) frequency stimuli presented alternately and at moderate intensity. Multiple regions on the superior temporal lobe exhibited responses that depended upon stimulus spectral content. Eight of these `frequency-dependent response regions' (FDRRs) were identified repeatedly across subjects. Four of the FDRRs exhibited a greater response to higher frequencies, and four exhibited a greater response to lower frequencies. Based upon the location of the eight FDRRs, a correspondence is proposed between FDRRs and anatomically defined cortical areas on the human superior temporal lobe. Our findings suggest that a larger number of tonotopically organized areas exist (i.e., four or more) in the human auditory cortex than was previously recognized. ß 2000 Elsevier Science B.V. All rights reserved. Key words: Auditory cortex; Functional magnetic resonance imaging; Tonotopy; Human 1. Introduction strated in structures throughout the auditory pathway, including auditory cortex (e.g., Rose et al., 1959; Wool- Tonotopy, an ordered mapping of neuronal fre- sey, 1971; Guinan et al., 1972; Merzenich and Reid, quency sensitivity to spatial location, has been demon- 1974). These demonstrations have typically involved re- cording from single or multiple units in non-human species and relating the acoustic frequency yielding the lowest response threshold (best frequency, BF) to * Corresponding author. Present address: School of Electrical and unit position (e.g., Hind, 1960; Merzenich and Brugge, Computer Engineering, Purdue University, West Lafayette, IN 47907, USA. Tel.: +1 (765) 494 5475; Fax: +1 (765) 494 6440; 1973; Merzenich et al., 1976; Reale and Imig, 1980; E-mail: [email protected] McMullen and Glaser, 1982; Sally and Kelly, 1988; Morel et al., 1993). Although neuronal responses in 1 Portions of this work were presented at the annual meeting of the International Society for Magnetic Resonance in Medicine (1996) and auditory cortex can depend on stimulus frequency in the annual meeting of the Association for Research in Otolaryngology complex ways, a single BF can usually be assigned to (1997). neurons in primary and certain non-primary areas (e.g., 2 Present address: University of Connecticut Health Center, Department of Neurology, 263 Farmington Ave., Farmington, CT Hind, 1960; Sutter and Schreiner, 1991; Rauschecker et 06030-1845, USA. al., 1995). Within cortical areas that are tonotopically 0378-5955 / 00 / $ ^ see front matter ß 2000 Elsevier Science B.V. All rights reserved. PII: S0378-5955(00)00203-3 HEARES 3571 1-11-00 Cyaan Magenta Geel Zwart 226 T.M. Talavage et al. / Hearing Research 150 (2000) 225^244 organized, BF varies fairly systematically from low to tinen et al., 1993; Cansino et al., 1994; Huotilainen et high along the cortical surface, but is relatively constant al., 1995; Verkindt et al., 1995; Roberts and Poeppel, across cortical depth (e.g., Merzenich et al., 1975; Imig 1996; Diesch and Luce, 1997; Lu«tkenho«ner and et al., 1977; Rauschecker et al., 1995). The overall pic- Steinstra«ter, 1998; Mu«hlnickel et al., 1998). Studies tak- ture of cortical frequency organization from the animal ing this approach typically used moderate-intensity, literature is one of multiple tonotopic maps distributed narrow-band stimuli based on the hypothesis that (a) over the cortical surface. neurons responding to these stimuli would have a nar- In contrast with the extensive body of data docu- row range of BFs and therefore occupy a limited extent menting the tonotopic organization of the auditory of any underlying tonotopic map, and (b) the location pathway in animals, far less is known about this funda- of the responding neurons would move systematically mental organizing principle in humans. This is true even from one end of the map to the other with systematic for auditory cortical areas residing on the superior tem- increases or decreases in acoustic stimulus frequency. It poral lobe, perhaps the most studied part of the human has been reported that the position of brain activity central auditory system. Based on physiological record- generating several evoked response components ings, lesion studies and functional imaging, it is known changes systematically with frequency (Romani et al., that widespread areas on the human superior temporal 1982a,b; Elberling et al., 1982; Pelizzone et al., 1985; lobe respond to sound and play a critical role in the Pantev et al., 1988, 1990, 1991, 1994, 1995, 1996; Ya- perception of acoustic stimuli (e.g., Celesia, 1976; Tra- mamoto et al., 1988, 1992; Tiitinen et al., 1993; Can- mo et al., 1990; Zatorre et al., 1992; Binder et al., sino et al., 1994; Huotilainen et al., 1995; Diesch and 1994). The primary auditory cortex, which lies deep Luce, 1997; Lu«tkenho«ner and Steinstra«ter, 1998; Mu«hl- within the Sylvian ¢ssure on the medial two-thirds of nickel et al., 1998). In some studies examining more Heschl's gyrus, is an area exhibiting short-latency re- than one response component in the same individuals, sponses to transient acoustic stimuli (a de¢ning feature the generators of the various components were localized of primary cortex) as well as cytoarchitectonic and im- to di¡erent parts of the superior temporal lobe and munostaining properties typical of primary sensory cor- each showed a systematic relationship between position tical areas (e.g., Celesia, 1976; Galaburda and Sanides, and stimulus frequency (Pantev et al., 1994, 1995, 1996; 1980; Lie¨geois-Chauvel et al., 1991; Rademacher et al., Diesch and Luce, 1997; Lu«tkenho«ner and Steinstra«ter, 1993; Rivier and Clarke, 1997). The surrounding, 1998). These ¢ndings indicate that human auditory cor- acoustically responsive areas of the superior temporal tex includes more than one tonotopically organized lobe are anatomically and physiologically di¡erentiable area. from the primary area, and from each other (e.g., Gal- Several studies have examined human cortical fre- aburda and Sanides, 1980; Lie¨geois-Chauvel et al., quency organization using positron emission tomogra- 1994; Rivier and Clarke, 1997; Howard et al., 2000). phy (PET) or functional magnetic resonance imaging If, as in many animal species, the various di¡erentiable (fMRI), techniques that provide spatial maps of brain areas contain one or more frequency-to-place mappings activation (Lauter et al., 1985; Wessinger et al., 1997; (e.g., Imig and Reale, 1980; Morel et al., 1993; Kosaki Bilecen et al., 1998; Lockwood et al., 1999; Yang et al., et al., 1997; Rauschecker et al., 1997), one would expect 2000). These maps show changes in blood £ow (PET) there to be multiple tonotopic representations of the or blood oxygenation (fMRI) that re£ect changes in audible frequency range on the surface of the human neural activity (e.g., in response to a sensory stimulus; superior temporal lobe. Fox and Raichle, 1986; Fox et al., 1988; Bandettini et Evidence that parts of human auditory cortex are al., 1992; Kwong et al., 1992; Ogawa et al., 1992). The tonotopically organized has been provided by previous PET and fMRI studies examining cortical frequency studies using a variety of techniques. Some of this evi- organization employed essentially the same strategy as dence comes from single unit recordings from auditory the magnetic and electric recording studies: subjects cortex in humans (Howard et al., 1996). However, the were stimulated with band-limited sound with the idea majority derives from studies using non-invasive meth- that the resulting activity would occupy di¡erent parts ods and provides somewhat di¡erent information about of auditory cortex. Each of the studies examined the cortical activity. The most extensively used approach response to two or three stimulus frequencies and re- has involved recording sound-evoked magnetic or elec- ported either displacements in the volume of activation tric responses over the surface of the head and localiz- for di¡erent frequencies, or separable sites of maximal ing the brain activity generating these responses (Ro- activation ^ ¢ndings consistent with an underlying to- mani et al., 1982a,b; Arlinger et al., 1982; Elberling et notopic organization. al., 1982; Pelizzone et al., 1985; Pantev et al., 1988, While it is clear that human auditory cortex is tono- 1990, 1991, 1994, 1995, 1996; Yamamoto et al., 1988, topically organized, the number of tonotopically organ- 1992; Bertrand et al., 1991; Jacobson et al., 1992; Tii- ized areas, the spatial arrangement of these areas, and HEARES 3571 1-11-00 Cyaan Magenta Geel Zwart T.M. Talavage et al. / Hearing Research 150 (2000) 225^244 227 their relationship to the cortical anatomy remains 2. Materials and methods largely unresolved. Although magnetic and electric re- cordings have indicated more than one tonotopically 2.1.
Load more

Recommended publications
  • A Search for Factors Specifying Tonotopy Implicates DNER in Hair-Cell Development in the Chick's Cochlea☆
    Developmental Biology 354 (2011) 221–231 Contents lists available at ScienceDirect Developmental Biology journal homepage: www.elsevier.com/developmentalbiology A search for factors specifying tonotopy implicates DNER in hair-cell development in the chick's cochlea☆ Lukasz Kowalik 1, A.J. Hudspeth ⁎ Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, Campus box 314, The Rockefeller University, 1230 York Avenue, New York, NY 10065–6399, USA article info abstract Article history: The accurate perception of sound frequency by vertebrates relies upon the tuning of hair cells, which are Received for publication 1 March 2011 arranged along auditory organs according to frequency. This arrangement, which is termed a tonotopic Revised 29 March 2011 gradient, results from the coordination of many cellular and extracellular features. Seeking the mechanisms Accepted 31 March 2011 that orchestrate those features and govern the tonotopic gradient, we used expression microarrays to identify Available online 8 April 2011 genes differentially expressed between the high- and low-frequency cochlear regions of the chick (Gallus gallus). Of the three signaling systems that were represented extensively in the results, we focused on the Keywords: ζ Auditory system notch pathway and particularly on DNER, a putative notch ligand, and PTP , a receptor phosphatase that Hair bundle controls DNER trafficking. Immunohistochemistry confirmed that both proteins are expressed more strongly Planar cell polarity in hair cells at the cochlear apex than in those at the base. At the apical surface of each hair cell, the proteins Signaling display polarized, mutually exclusive localization patterns. Using morpholinos to decrease the expression of DNER or PTPζ as well as a retroviral vector to overexpress DNER, we observed disturbances of hair-bundle morphology and orientation.
    [Show full text]
  • The Topographic Unsupervised Learning of Natural Sounds in the Auditory Cortex
    The topographic unsupervised learning of natural sounds in the auditory cortex Hiroki Terashima Masato Okada The University of Tokyo / JSPS The University of Tokyo / RIKEN BSI Tokyo, Japan Tokyo, Japan [email protected] [email protected] Abstract The computational modelling of the primary auditory cortex (A1) has been less fruitful than that of the primary visual cortex (V1) due to the less organized prop- erties of A1. Greater disorder has recently been demonstrated for the tonotopy of A1 that has traditionally been considered to be as ordered as the retinotopy of V1. This disorder appears to be incongruous, given the uniformity of the neocortex; however, we hypothesized that both A1 and V1 would adopt an efficient coding strategy and that the disorder in A1 reflects natural sound statistics. To provide a computational model of the tonotopic disorder in A1, we used a model that was originally proposed for the smooth V1 map. In contrast to natural images, natural sounds exhibit distant correlations, which were learned and reflected in the disor- dered map. The auditory model predicted harmonic relationships among neigh- bouring A1 cells; furthermore, the same mechanism used to model V1 complex cells reproduced nonlinear responses similar to the pitch selectivity. These results contribute to the understanding of the sensory cortices of different modalities in a novel and integrated manner. 1 Introduction Despite the anatomical and functional similarities between the primary auditory cortex (A1) and the primary visual cortex (V1), the computational modelling of A1 has proven to be less fruitful than V1, primarily because the responses of A1 cells are more disorganized.
    [Show full text]
  • Conserved Role of Sonic Hedgehog in Tonotopic Organization of the Avian Basilar Papilla and Mammalian Cochlea
    Conserved role of Sonic Hedgehog in tonotopic organization of the avian basilar papilla and mammalian cochlea Eun Jin Sona,1, Ji-Hyun Mab,c,1, Harinarayana Ankamreddyb,c, Jeong-Oh Shinb, Jae Young Choia,c, Doris K. Wud, and Jinwoong Boka,b,c,2 Departments of aOtorhinolaryngology and bAnatomy, and cBK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea; and dLaboratory of Molecular Biology, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892 Edited by Clifford J. Tabin, Harvard Medical School, Boston, MA, and approved February 11, 2015 (received for review September 16, 2014) Sound frequency discrimination begins at the organ of Corti in several important questions remain about the development of mammals and the basilar papilla in birds. Both of these hearing the tonotopic organization of the cochlea: (i) What is the signaling organs are tonotopically organized such that sensory hair cells pathway(s) upstream of Bmp7 and RA? and (ii) are Bmp7 and at the basal (proximal) end respond to high frequency sound, RA also required for establishing the tonotopy in the mammalian whereas their counterparts at the apex (distal) respond to low inner ear? frequencies. Sonic hedgehog (Shh) secreted by the developing The Shh signaling pathway is of particular interest in cochlear notochord and floor plate is required for cochlear formation in tonotopic development for several reasons. First, the require- both species. In mice, the apical region of the developing cochlea, ment of Shh emanating from the floor plate and notochord closer to the ventral midline source of Shh, requires higher levels appears conserved between chicken and mouse (8–11).
    [Show full text]
  • Quantifying Attentional Modulation of Auditory-Evoked Cortical Responses from Single-Trial Electroencephalography
    ORIGINAL RESEARCH ARTICLE published: 04 April 2013 HUMAN NEUROSCIENCE doi: 10.3389/fnhum.2013.00115 Quantifying attentional modulation of auditory-evoked cortical responses from single-trial electroencephalography Inyong Choi 1, Siddharth Rajaram 1, Lenny A. Varghese 1,2 and Barbara G. Shinn-Cunningham 1,2* 1 Center for Computational Neuroscience and Neural Technology, Boston University, Boston, MA, USA 2 Department of Biomedical Engineering, Boston University, Boston, MA, USA Edited by: Selective auditory attention is essential for human listeners to be able to communicate John J. Foxe, Albert Einstein College in multi-source environments. Selective attention is known to modulate the neural of Medicine, USA representation of the auditory scene, boosting the representation of a target sound Reviewed by: relative to the background, but the strength of this modulation, and the mechanisms Kimmo Alho, University of Helsinki, Finland contributing to it, are not well understood. Here, listeners performed a behavioral Sarah E. Donohue, Duke University, experiment demanding sustained, focused spatial auditory attention while we measured USA cortical responses using electroencephalography (EEG). We presented three concurrent *Correspondence: melodic streams; listeners were asked to attend and analyze the melodic contour of one Barbara G. Shinn-Cunningham, of the streams, randomly selected from trial to trial. In a control task, listeners heard the Auditory Neuroscience Laboratory, Center for Computational same sound mixtures, but performed the contour judgment task on a series of visual Neuroscience and Neural arrows, ignoring all auditory streams. We found that the cortical responses could be Technology, Boston University, fit as weighted sum of event-related potentials evoked by the stimulus onsets in the 677 Beacon St., Boston, competing streams.
    [Show full text]
  • The Topography of Frequency and Time Representation in Primate Auditory
    RESEARCH ARTICLE elifesciences.org The topography of frequency and time representation in primate auditory cortices Simon Baumann1*, Olivier Joly1,2, Adrian Rees1, Christopher I Petkov1, Li Sun1, Alexander Thiele1, Timothy D Griffiths1 1Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom; 2MRC Cognition and Brain Sciences Unit, Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom Abstract Natural sounds can be characterised by their spectral content and temporal modulation, but how the brain is organized to analyse these two critical sound dimensions remains uncertain. Using functional magnetic resonance imaging, we demonstrate a topographical representation of amplitude modulation rate in the auditory cortex of awake macaques. The representation of this temporal dimension is organized in approximately concentric bands of equal rates across the superior temporal plane in both hemispheres, progressing from high rates in the posterior core to low rates in the anterior core and lateral belt cortex. In A1 the resulting gradient of modulation rate runs approximately perpendicular to the axis of the tonotopic gradient, suggesting an orthogonal organisation of spectral and temporal sound dimensions. In auditory belt areas this relationship is more complex. The data suggest a continuous representation of modulation rate across several physiological areas, in contradistinction to a separate representation of frequency within each area. DOI: 10.7554/eLife.03256.001 Introduction *For correspondence: simon. Frequency structure (spectral composition) and temporal modulation rate are fundamental [email protected] dimensions of natural sounds. The topographical representation of frequency (tonotopy) is a well- established organisational principle of the auditory system. In mammals, tonotopy is established in the Competing interests: The receptor organ, the cochlea, and maintained as a systematic spatial separation of different authors declare that no competing interests exist.
    [Show full text]
  • Bedside Evaluation of the Functional Organization of the Auditory Cortex in Patients with Disorders of Consciousness
    RESEARCH ARTICLE Bedside Evaluation of the Functional Organization of the Auditory Cortex in Patients with Disorders of Consciousness Julie Henriques1,2, Lionel Pazart3,4, Lyudmila Grigoryeva1, Emelyne Muzard5, Yvan Beaussant6, Emmanuel Haffen3,4,7, Thierry Moulin3,4,5, Régis Aubry3,4,6, Juan- Pablo Ortega1,8, Damien Gabriel3,4* 1 Laboratoire de Mathématiques de Besançon, Besançon, France, 2 Cegos Deployment, Besançon, France, 3 INSERM CIC 1431 Centre d’Investigation Clinique en Innovation Technologique, CHU de Besançon, Besançon, France, 4 EA 481 Laboratoire de Neurosciences de Besançon, Besançon, France, 5 Service de neurologie, CHU de Besançon, Besançon, France, 6 Département douleur soins palliatifs, CHU de Besançon, Besançon, France, 7 Service de Psychiatrie de l’adulte, CHU de Besançon, Besançon, France, 8 Centre National de la Recherche Scientifique (CNRS), Paris, France * [email protected] OPEN ACCESS Abstract Citation: Henriques J, Pazart L, Grigoryeva L, Muzard E, Beaussant Y, Haffen E, et al. (2016) To measure the level of residual cognitive function in patients with disorders of conscious- Bedside Evaluation of the Functional Organization of ness, the use of electrophysiological and neuroimaging protocols of increasing complexity the Auditory Cortex in Patients with Disorders of is recommended. This work presents an EEG-based method capable of assessing at an Consciousness. PLoS ONE 11(1): e0146788. doi:10.1371/journal.pone.0146788 individual level the integrity of the auditory cortex at the bedside of patients and can be seen as the first cortical stage of this hierarchical approach. The method is based on two features: Editor: Lawrence M Ward, University of British Columbia, CANADA first, the possibility of automatically detecting the presence of a N100 wave and second, in showing evidence of frequency processing in the auditory cortex with a machine learning Received: September 14, 2015 based classification of the EEG signals associated with different frequencies and auditory Accepted: December 22, 2015 stimulation modalities.
    [Show full text]
  • Processing of Natural Sounds in Human Auditory Cortex: Tonotopy, Spectral Tuning, and Relation to Voice Sensitivity
    The Journal of Neuroscience, October 10, 2012 • 32(41):14205–14216 • 14205 Behavioral/Systems/Cognitive Processing of Natural Sounds in Human Auditory Cortex: Tonotopy, Spectral Tuning, and Relation to Voice Sensitivity Michelle Moerel,1,2 Federico De Martino,1,2 and Elia Formisano1,2 1Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, The Netherlands, and 2Maastricht Brain Imaging Center, 6229 ER Maastricht, The Netherlands Auditory cortical processing of complex meaningful sounds entails the transformation of sensory (tonotopic) representations of incom- ing acoustic waveforms into higher-level sound representations (e.g., their category). However, the precise neural mechanisms enabling such transformations remain largely unknown. In the present study, we use functional magnetic resonance imaging (fMRI) and natural sounds stimulation to examine these two levels of sound representation (and their relation) in the human auditory cortex. In a first experiment,wederivecorticalmapsoffrequencypreference(tonotopy)andselectivity(tuningwidth)bymathematicalmodelingoffMRI responses to natural sounds. The tuning width maps highlight a region of narrow tuning that follows the main axis of Heschl’s gyrus and is flanked by regions of broader tuning. The narrowly tuned portion on Heschl’s gyrus contains two mirror-symmetric frequency gradients, presumably defining two distinct primary auditory areas. In addition, our analysis indicates that spectral preference and selectivity (and their topographical organization) extend well beyond the primary regions and also cover higher-order and category- selective auditory regions. In particular, regions with preferential responses to human voice and speech occupy the low-frequency portions of the tonotopic map. We confirm this observation in a second experiment, where we find that speech/voice selective regions exhibit a response bias toward the low frequencies characteristic of human voice and speech, even when responding to simple tones.
    [Show full text]
  • Cortical Markers of Auditory Stream Segregation Revealed for Streaming Based on Tonotopy but Not Pitch
    Cortical markers of auditory stream segregation revealed for streaming based on tonotopy but not pitch Dorea R. Ruggles and Alexis N. Tausend Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, Minnesota 55455, USA Shihab A. Shamma Electrical and Computer Engineering Department & Institute for Systems, University of Maryland, College Park, Maryland 20740, USA Andrew J. Oxenhama) Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, Minnesota 55455, USA (Received 5 July 2018; revised 5 October 2018; accepted 8 October 2018; published online 29 October 2018) The brain decomposes mixtures of sounds, such as competing talkers, into perceptual streams that can be attended to individually. Attention can enhance the cortical representation of streams, but it is unknown what acoustic features the enhancement reflects, or where in the auditory pathways attentional enhancement is first observed. Here, behavioral measures of streaming were combined with simultaneous low- and high-frequency envelope-following responses (EFR) that are thought to originate primarily from cortical and subcortical regions, respectively. Repeating triplets of har- monic complex tones were presented with alternating fundamental frequencies. The tones were fil- tered to contain either low-numbered spectrally resolved harmonics, or only high-numbered unresolved harmonics. The behavioral results confirmed that segregation can be based on either tonotopic or pitch cues. The EFR results revealed no effects of streaming or attention on subcortical responses. Cortical responses revealed attentional enhancement under conditions of streaming, but only when tonotopic cues were available, not when streaming was based only on pitch cues. The results suggest that the attentional modulation of phase-locked responses is dominated by tonotopi- cally tuned cortical neurons that are insensitive to pitch or periodicity cues.
    [Show full text]
  • Hearing Things
    Hearing Things How Your Brain Works Prof. Jan Schnupp [email protected] HowYourBrainWorks.net//hearing 1) Things Make Sounds, and Different Things Make Different Sounds Sound Signals • Many physical objects emit sounds when they are “excited” (e.g. hit or rubbed). • Sounds are just pressure waves rippling through the air, but they carry a lot of information about the objects that emitted them. (Example: what are these two objects? Which one is heavier, object A or object B ?) • The sound (or signal) emitted by an object (or system) when hit is known as the impulse response. • Impulse responses of everyday objects can be quite complex, but the sine wave is a fundamental ingredient of these (or any) complex sounds (or signals). Vibrations of a Spring-Mass System Undamped 1. F = -k·y (Hooke’s Law) 2. F = m · a (Newton’s 2nd) 3. a = dv/dt = d2y/dt2 -k · y = m · d2y/dt2 y(t) = yo · cos(t · k/m) Damped 4. –k·y –r dy/dt = d2y/dt2 (-r·t/2m) Don’ty(t) =worry yo·e about thecos(t· formulaek/m!- Just remember(r/2m) that2) mass-spring systems like to vibrate at a rate proportional to the square-root of their “stiffness” and inversely proportional to their weight. https://auditoryneuroscience.com/shm Sound wave propagation Resonant Cavities • In resonant cavities, “lumps of air” at the entrance/exit of the cavity oscillate under the elastic forces exercised by the air inside the cavity. • The preferred resonance frequency is inversely proportional to the square root of the volume.
    [Show full text]
  • Study of Fluid Flow Within the Hearing Organ
    Study of fluid flow within the hearing organ Xavier Meyer1, Elisabeth Delevoye2 and Bastien Chopard1 1Department of Computer Science, University of Geneva, Switzerland. 2CEA-Grenoble DRT/DSIS/SCSE, France. Abstract Georg Von B´ek´esywas awarded a nobel price in 1961 for his pi- oneering work on the cochlea function in the mammalian hearing or- gan [2]. He postulated that the placement of sensory cells in the cochlea corresponds to a specific frequency of sound. This theory, known as tonotopy, is the ground of our understanding on this complex organ. With the advance of technologies, this knowledge broaden continuously and seems to confirm B´ek´esyinitial observations. However, a mystery still lies in the center of this organ: how does its microscopic tissues exactly act together to decode the sounds that we perceive ? One of these tissues, the Reissner membrane, forms a double cell layer elastic barrier separating two fundamental ducts of this organ. Yet, until recently [16], this membrane, was not considered in the modelling of the inner ear due to its smallness. Nowadays, objects of this size are at the reach of the medical imagining and measuring expertise [18, 4, 16]. Newly available observations coupled with the increasing availability of computational resources should enable mod- ellers to consider the impact of these microscopic tissues in the inner ear mechanism. In this report, we explore the potential fluid-structure interactions happening in the inner ear, more particularly on the Reissner mem- brane. This study aims at answering two separate questions : • Can nowadays computational fluid dynamics solvers simulate in- teraction with inner ear microscopic tissues ? • Has the Reissner membrane function on the auditory system been overlooked ? This report is organized as follow.
    [Show full text]
  • Evidence of a Tonotopic Organization of the Auditory Cortex in Cochlear Implant Users
    7838 • The Journal of Neuroscience, July 18, 2007 • 27(29):7838–7846 Development/Plasticity/Repair Evidence of a Tonotopic Organization of the Auditory Cortex in Cochlear Implant Users Jeanne Guiraud1,3,6 Julien Besle,2,6 Laure Arnold,5 Patrick Boyle,5 Marie-He´le`ne Giard,2,6 Olivier Bertrand,2,6 Arnaud Norena,1,6 Eric Truy,1,4,6 and Lionel Collet1,3,6 1CNRS UMR 5020, Neurosciences and Sensorial Systems Laboratory, Lyon, F-69000, France, and 2INSERM, U821, Lyon, F-69500, France, Departments of 3Audiology and Otorhinolaryngology and 4Otolaryngology and Head and Neck Surgery, Edouard Herriot University Hospital, Lyon, F-69000, France, 5Clinical Research Department, Advanced Bionics, Cambridge CB22 5LD, United Kingdom, and 6 Universite´ Lyon, Lyon, F-69000, France Deprivation from normal sensory input has been shown to alter tonotopic organization of the human auditory cortex. In this context, cochlear implant subjects provide an interesting model in that profound deafness is made partially reversible by the cochlear implant. In restoring afferent activity, cochlear implantation may also reverse some of the central changes related to deafness. The purpose of the present study was to address whether the auditory cortex of cochlear implant subjects is tonotopically organized. The subjects were thirteen adults with at least 3 months of cochlear implant experience. Auditory event-related potentials were recorded in response to electrical stimulation delivered at different intracochlear electrodes. Topographic analysis of the auditory N1 component (ϳ85 ms latency) showed that the locations on the scalp and the relative amplitudes of the positive/negative extrema differ according to the stimulated electrode, suggesting that distinct sets of neural sources are activated.
    [Show full text]
  • Specific Tonotopic Organizations of Different Areas of the Human Auditory Cortex Revealed by Simultaneous Magnetic and Electric Recordings
    ELSEVIER Electroencephalography and clinical Neurophysiology 94 (1995) 26-40 Specific tonotopic organizations of different areas of the human auditory cortex revealed by simultaneous magnetic and electric recordings C. Pantev *, O. Bertrand a, C. Eulitz, C. Verkindt a, S. Hampson, G. Schuierer b, T. Elbert Center ofBiomagnetism, Institute ofExperimental Audiology University ofMunster, Kardinal-von-Galen-Ring 10, D-48129 Munster, Germany , Brain Signals and Processes Laboratory, INSERM Unite 280, F-69003 Lyon, France b Institute ofClinical Radiology, University ofMunster, D-48I29 Munster, Germany Accepted for publication: 19 July 1994 Abstract This paper presents data concerning auditory evoked responses in the middle latency range (wave Pam/ Pa) and slow latency range (wave Nlm/Nl) recorded from 12 subjects. It is the first group study to report multi-channel data of both MEG and EEG recordings from the human auditory cortex. The experimental procedure involved potential and current density topographical brain mapping as well as magnetic and electric source analysis. Responses were compared for the following 3 stimulus frequencies: 500, 1000 and 4000 Hz. It was found that two areas of the auditory cortex showed mirrored tonotopic organization; one area, the source of Nlm/Nl wave, exhibited higher frequencies at progressively deeper locations, while the second area, the source of the Pam/Pa wave, exhibited higher frequencies at progressively more superficial locations. The Pa tonotopic map was located in the primary auditory cortex anterior to the Nlm/Nl mirror map. It is likely that Nlm/Nl results from activation of secondary auditory areas. The location of the Pa map in AI, and its NI mirror image in secondary auditory areas is in agreement with observations from animal studies.
    [Show full text]