language-and-brain

Chapter12LanguageandBrainNeurolinguisticsNeurolinguisticsisthestudyoftherelationshipbetweenbrainandlanguage.Itincludesresearchinto◇howthestructureofthebraininfluenceslanguagelearning◇howandinwhichpartsofthebrainlanguageisstored◇howdamagetothebrainaffectstheabilitytouselanguageLateralizationoftheBrainHumanbodyisasymmetrical:heart,liver,useoflimbs,etc.FunctionsofthebrainbecomelateralizedEachhemispherespecializedforparticularwaysofworkingSplit-brainpatientsaregoodexamplesoflateralizationoflanguagefunctionsBrainLateralization(大脑侧化)Brainlateralizationreferstothelocalizationofcognitiveandperceptualfunctionsinaparticularhemisphereofthebrain.Forexampletherighthemisphereprocessesstimulimoreholisticallyandthelefthemispheremoreanalytically.Inmostpeople,thelefthemispherehasprimaryresponsibilityforlanguage,whiletherighthemispherecontrolsvisualandspatialskills.认知功能和感知功能位于大脑的某一半球上被称为侧化。LateralizationoffunctionsLeft-hemisphere:SequentialanalysisAnalyticalProblemsolvingLanguageRight-hemisphere:SimultaneousanalysisSyntheticVisual-SpatialskillsCognitivemapsPersonalspaceFacialrecognitionDrawingEmotionalfunctionsRecognizingemotionsExpressingemotionsMusicMethodstoStudytheBrainSAT(阿米妥纳试验)CT(计算机化轴向层面X射线摄影法CT扫描)PET（正电子发射X射线层析照相术）SplitBrainStudies（裂脑试验）DichoticListening(两耳分听研究)ThreemajortypesofAphasiaBorca’saphasiaNonfluentspeechWernicke’saphasiaFluentspeechbutunintelligibleGlobalaphasiaTotallossoflanguageBrainareasinvolvedinLanguageBroca’sAphasiaLesionsintheleftinferiorfrontalregion(Broca’sarea)Nonfluent,labored,andhesitantspeechMostalsolosttheabilitytonamepersonsorsubjects(anomia)Canutterautomaticspeech(“hello”)ComprehensionrelativelyintactMostalsohavepartialparalysisofonesideofthebody(hemiplegia)Ifextensive,notmuchrecoveryovertimeWernicke’sAphasiaLesionsinposterioroftheleftsuperiortemporalgyrus,extendingtoadjacentparietalcortexFluentspeechButcontainsmanyparaphasias“girl”-“curl”,“bread”-“cake”SyntacticalbutemptysentencesCannotrepeatwordsorsentencesUnabletounderstandwhattheyreadorhearUsuallynopartialparalysisSignLanguagesFull-fledgedlanguages,createdbyhearing-impairedpeople(notbyLinguists):Dialects,jokes,poems,etc.Donotresemblethespokenlanguageofthesamearea(ASLresemblesBantuandNavaho)Pinker:NicaraguanSignLanguageAnotherevidenceoftheoriginsoflanguage(gestures)MostgesturesinASLarewithright-hand,orelsebothhands(lefthemispheredominance)SignerswithbraindamagetosimilarregionsshowaphasiaaswellSignerAphasiaYoungman,bothspokenandsignlanguage:AccidentanddamagetobrainBothspokenandsignlanguagesareaffectedDeaf-muteperson,signlanguage:Strokeanddamagetoleft-sideofthebrainImpairmentinsignlanguage3deafsigners:DifferentdamagestothebrainwithdifferentimpairmentstogrammarandwordproductionDyslexia（难语症）ProbleminlearningtoreadCommoninboysandleft-handedHighIQ,sorelatedwithlanguageonlyAcquireddyslexia(习得性失读症)Damageinandaroundtheangulargyrus(角形脑回：位于维尼克区的后面。它负责把视觉刺激转化成听觉形式或把听觉形式转换成视觉刺激。)oftheparietallobeoftencausestheimpairmentofreadingandwritingability,whichisoftenreferredtoasacquireddyslexia.PhonologicaldyslexiaSurfacedyslexiaAcquiredDyslexia=AlexiaDisorderinadulthoodasaresultofdiseaseorinjuryDeepdyslexia(paysattn.towholes):“cow”-“horse”,cannotreadabstractwordsFailstoseesmalldifferences(donotreadeachletter)ProblemswithnonsensewordsSurfacedyslexia(paysattn.todetails):NonsensewordsarefineSuggests2differentsystems:OnefocusedonthemeaningsofwholewordsTheotheronthesoundsofwordsSplit-brainEpilepticactivityspreadfromonehemispheretotheotherthrucorpuscallosumSince1930,suchepileptictreatedbyseveringtheinterhemisphericpathwaysAtfirstnodetectiblechanges(e.g.IQ)Animalresearchrevealeddeficits:CatwithbothcorpuscallosumandopticchiasmseveredLeft-hemispherecouldbetrainedforsymbol:rewardRight-hemispherecouldbetrainedforinvertedsymbol:rewardLeftvs.RightBrainPreandpostoperationstudiesshowedthat:Selectivestimulationoftherightandlefthemispherewaspossiblebystimulatingdifferentpartsofthebody(e.g.right/lefthand):ThuscantestthecapabilitiesofeachhemisphereLefthemispherecouldreadandverballycommunicateRighthemispherehadsmalllinguisticcapacity:recognizesinglewordsVocabularyandgrammarcapabilitiesofrightisfarlessthanleftOnlytheprocessestakingplaceinthelefthemispherecouldbedescribedverballyOtherstudiesRightearadvantageindicothiclistening:DuetointerhemisphericcrossingWordsinleft-hemisphere,MusicinrightSupportedbydamageandimagingstudiesButperfect-pitchisstillontheleftAsymmetryinplanumtemporale:Musicianswithperfect-pitchhas2xlargerPTEvidentinnewborns,thussuggestinginnatebasisforcerebralspecializationforlanguageandspeechPrecisionofstimulusanalysisinthebrainisreducedonthemidlineareasofthebodySpeechorgans(vocaltract,tongue,larynx,etc.)areinthemidlineAsymmetryofmotorcontrolofspeechareas(sidednessinlanguage)providesunchallengedcontrolObservedinsongbirdstooButhemisphericdominanceisnotabsolute,bothsidesarenecessary:Aftercommisurotomy,leftisbetterthanright,butbothareaffectedEffectsofAgingonNervousSystem•Gradualdeclineinsensoryandmotorfunction•Reflexesslow•Sizeandweightofbraindecrease–Decreasedshort-te