Auditory information processing in systems with internally coupled ears [Elektronische Ressource] / Christine Voßen

Christine Vossen

Description

Auditory Information Processingin Systems withInternally Coupled EarsChristine Vo enAThis dissertation has been written in LT X us-Eing the memoir class. Typesetting was done withApdfLT X.EFunding has been provided by the Bernstein Cen-ter for Computational Neuroscience (BCCN) { Mu-nich. TECHNISCHE UNIVERSITAT MUNCHENLehrstuhl fur Theoretische PhysikAuditory Information Processingin Systems withInternally Coupled EarsChristine Vo enVollst andiger Abdruck der von der Fakult at fur Physik der Technischen Universit atMunc hen zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaftengenehmigten Dissertation.Vorsitzender: Univ.-Prof. Dr. F. SimmelPrufer der Dissertation: 1. Univ.-Prof. Dr. J. L. van Hemmen2. Univ.-Prof. Dr. F. BornemannDie Dissertation wurde am 12.07.2010 bei der Technischen Universit at Munc hen eingereichtund durch die Fakult at fur Physik am 27.07.2010 angenommen.. . . es sind uns Dinge als au er uns be ndlicheGegenst ande unserer Sinne gegeben, allein von dem, wassie an sich selbst sein m ogen, wissen wir nichts, sondernkennen nur ihre Erscheinungen, d. i. die Vorstellungen,die sie in uns wirken, indem sie unsere Sinne a zieren.Immanuel Kant (1724 { 1804)Prolegomena, 1783ContentsContents vii1 Introduction 11.1 Sound stimuli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Mechanical processing of sound stimuli . . . . . . . . . . . . . . . . . . . . . 31.2.

Sujets

• Physik

Informations

• Publié par: technische_universitat_munchen
• Publié le: 01 janvier 2010
• Nombre de lectures: 28
• Langue: English
• Poids de l'ouvrage: 77 Mo

Extrait

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viitstenCon1ductiontroIn11.1Soundstimuli...................................2
1.2Mechanicalprocessingofsoundstimuli.....................3
1.2.1Evolutionofdifferentauditorysystems.................3
1.2.2Internallycoupledears..........................3
1.3Neuronalprocessingofsoundstimuli......................5
1.3.1Buildingblocksofneuronalcomputation................5
1.3.2Leakyintegrate-and-fireneuron.....................9
1.3.3Poissonneuron..............................10
1.4Neuronalrepresentationofsoundstimuli....................13
1.4.1Neuronalmaps..............................13
1.4.2Pre-wiringamap.............................13
1.4.3Fine-tuningamap............................14
2ModelingInternallyCoupledEars:TheICEmodel17
2.1Introduction....................................17
2.2DerivationoftheICEmodelwithcylindricalmouthcavity.........21
2.2.1Externalsoundinput...........................22
2.2.2Internalcavity..............................23
2.2.3Vibrationofthemembrane.......................25
2.3Numericalsimulationoftheeigenfunctions
ofrealisticmouthcavities............................31
2.4Evaluationandresults..............................33
2.4.1Directionalityofthemembranevibrationpattern...........34
2.4.2Eigenmodesofarealisticmouthcavity.................39
2.4.3GeneralizationoftheICEmodel....................42
2.4.4Spatialvibrationpatternofthemembrane...............49
2.5Conclusion....................................50
3NeuronalprocessingofiTDsandiADs53
3.1Introduction....................................53
3.2SeparatedpathwaysforiTDandiADprocessing...............54
3.3ProcessingofiTDs................................55

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3.4ProcessingofiADs................................62
3.4.1Experimentalandnaturalstimulus...................63
3.4.2Simulationofnucleusangularis(NA)..................64
3.4.3SimulationofEIneurons........................65
3.5Conclusion....................................69
AuditorySensitivityandInternallyCoupledEars73
4.1Introduction....................................73
4.2Theoreticaldescriptionofmembranevibrations................75
4.2.1Membranevibrationdifferencesofindependentears.........77
4.2.2Membranevibrationdifferencesofinternallycoupledears......78
4.2.3Empiricalanalysis............................79
4.3Conclusion....................................82
4.AMethods:Empiricalanalysis...........................82
Optimalityinmono-andmultisensorymapformation87
5.1Introduction....................................87
5.2Fundamentalconceptofneuronalmaps....................89
5.3Mathematicalmodel...............................91
5.3.1Definitionoftheproblem........................92
5.3.2Optimalreconstruction.........................94
5.3.3Matrixnotation.............................97
5.3.4Relationtothemaximum-likelihoodapproach.............98
5.3.5Neuronalrealizationofthemodel....................99
5.4Arecipeofmakingmaps.............................100
5.5Multimodality...................................101
5.5.1Multimodalinteraction.........................101
5.5.2Developmentofmultisensoryspace...................102
5.6Discussion.....................................104
5.ANonlinearitiesininformationprocessing....................105
5.BSelf-averaging...................................105
5.CRemainingderivationstepsleadingto(5.23)..................106
5.DGaussianblurredsignal.............................109
111formationmapdalMultimo6.1Introduction....................................111
6.2Theintegratedmultimodalteacher.......................114
6.2.1HowdounisensorymapsdetermineiMT?...............114
6.2.2HowdoiMTcharacteristicsinfluencemapadaptation?........118
6.2.3HowdoesiMTcalibratedifferentunimodalmaps?..........122
6.3ApplicationsoftheiMTconcept........................122
6.3.1Experimentspro-vision-guidedmapformation.............122
6.3.2Experimentscontra-vision-guidedmapformation...........126
6.4Discussion.....................................128
6.AOptimalcombinationoftwomodalities.....................129

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Thischapterintroducesthefundamentalsofsensoryinformationprocessing,focusingon
theprocessingofsoundsignalsastheauditorysystemisoneofthemostwidespreadof
thevarioussensorysystems.Theprominentroleoftheauditorysystemcanbeexplained
bythespecificpropertiesofsoundperception,namely,hearingisomnidirectionalandits
processingisveryfast.Incomparisontolight,soundwaveshaveamuchlongerwavelength
sotheyarenotblockedbysmallobjects.Wecan,forinstance,hearsomethingbehinda
treebutwecannotseeit.Amongstotheradvantagesauditionthereforeoffersthepossibility
toreacttoapproachingdangersthatarenotyetvisible.Toexploitthelatteradvantage,
itisessentialthatananimalcanlocalizeasoundsource,otherwisethepreycouldtryto
escapeinthedirectionofthepredator.Todeterminethedirectionofasoundstimulus,
severalstepsarenecessaryintheanimalsstudiedinthisthesis.
First,anobjectevokesanauditorystimulus.Section1.1describeshowsuchastimulus
propagatesthroughthesurroundingmediumandisamplifiedbeforearrivingatthe
animal.theofdetectorsSecond,thearrivingsoundwavesexcitethetympani,apairofthinmembranesthat
arepartofthemechanicalauditorysystem.Theanatomyoftheauditorysystemishighly
variable.Theprimaryfocusofthisworkisoninternallycoupledears(ICE)inwhichone
membranecaninfluencevibrationoftheotherthroughinternalcavities;seeSec.1.2.
Third,tympanicvibrationsareprocessedneuronally.Thefundamentalelementof
neuronalcomputationistheneuronalnet,consistingofneuronsasbuildingblocksand
thevariableconnectionsbetweenthem,calledsynapses.Section1.3reviewsthegeneral
functionandmathematicalmodelingofneuronsandsynapses.
Fourth,asresultofneuronalcomputation,sensorystimuligiverisetoneuronalrep-
resentationsofthestimuli,i.e.,neuronalmaps;seeSec.1.4.Eachneuronofthemap
representsaspecificproperty,e.g.,thestimulusataspecificpointinspace.Neighboring
neuronsrespondtosimilarsensoryinputs.Neuronalmapsreconstructthestimulusaswell

1

troIn1.duction

aspossible,i.e.,optimallywithinthelimitsofprocessing.Theprecisecalibrationofthe
synapsesrequiredforstimulusreconstructionresultsfromanexperience-basedlearning
processthattakesintoaccountinputsfromallavailablesensorysystems.

ulistimSound1.1Soundwavesareoscillationsofpressurethataretransmittedthroughtheair.Asound
stimulusiscreatedwhenamovementcompressesthesurroundingairandcreatestraveling
soundwavesthatarriveatthetympaniofananimal.Dependingonthespatialrelationship
betweenthetwotympaniandthesoundsource,thearrivingsoundwavesdifferinphaseand
amplitudebetweenthetympani.Thesedifferencesaredenotedasinterauraltimedifferences
(sideITDofs)theandinhead,terauralforinstance,amplitudearrivesatdifferencesthe(facing,IADs).i.e.A,soundipsilaterwalavtefromympanaumsourceearlieratandone
withhigheramplitudethanattheaverted,i.e.,contralateraltympanum.Asoundwave
fromasourceinfrontofthehead,incontrast,arrivesatbothearssimultaneouslyandwith
thesameamplitude.ThesetwoexamplesdemonstratethatITDsandIADscanencode
thedirectionofasoundsource.AnevaluationofITDsandIADsasperformedbythe
auditorysystemandtheconsequentneuronalcircuitscouldthereforedecodethesound
direction.source

2

Figure1.1:Evolutionofvertebrateears.Duringthetransitionfromwatertoland,tympanic
middleearscapableofreceivingairbornesoundevolvedseparatelyamongtheancestorsof
moderncross-sectionsfrogs,throughturtles,diffeli