简介:Pilotspatialdisorientationisaleadingfactorcontributingtomanyfatalflyingaccidents.Spatialorientationistheproductofintegrativeinputsfromtheproprioceptive,vestibular,andvisualsystems.Vestibularneuritis(VN)canleadtosuddenpilotincapacitationinflight.VNiscommonlydiagnosedbydemonstrationofunilateralvestibularfailure,asunilaterallossofcaloricresponse.Asthistestreflectsthefunctionofthesuperiorpartofthevestibularnerveonly,casesofpureinferiornerveneuritiswillbelost.ThispaperdescribesafighterpilotwithsymptomssuggestiveofVNbutwithnormalcalorictestresults.Furthertestshowedunilaterallossofvestibularevokedmyogenicpotential.Webelievethatthepilotsufferedfrompureinferiornervevestibularneuritis.VEMPplaysamajorroleinthediagnosisofinferiornervevestibularneuritisinpilots.Aeromedicalconcernsarealsodiscussed.
简介:Growingevidencehasbeenfoundtosuggestthatearlydevelopmentofthecentralauditorysystemisdependentonacousticstimuli.Peripheraldamagecausedbynoiseexposureandototoxicdrugscaninducefunctionalandanatomicalchangesalongtheauditorypathways.Theinferiorcolliculus(IC)isauniquestructureintheauditorysystemlocatedbetweentheprimaryauditorynucleiofthebrainstemandthethala-mus.DamagetotheICinhibitorycircuitrymayaffectcentralauditoryprocessingandsoundperception.Here,wereviewsomeofthestrikingelectrophysiologicalchangesintheICthatoccurafternoiseexposureandototoxicdrugtreatment.AcommonoccurrencethatemergesintheICafterperipheraldamageishyper-excitabilityofsound-evokedresponse.ThehyperexcitabilityoftheICislikelyrelatedwithreducedinhibi-toryresponsethatrequiresnormalperipheralinputs.Earlyagehearinglosscanresultinalonglastingin-creasedsusceptibilitytoaudiogenicseizurewhichisrelatedtohyperactivityintheICevokedbyloudsounds.OurstudiessuggestthathearinglosscancauseincreasedICneuronresponsivenesswhichmayberelatedtotinnitus,hyperacusis,andaudiogenicseizure.
简介:FragileXsyndromeisthemostcommonformofinheritedmentalretardationaffectingupto1in4000individuals.ThesyndromeisinducedbyamutationintheFMR1gene,causingadeficiencyinitsgeneby-productFMRP.ImpairmentinthenormalfunctioningofFMRPleadstolearningandmemorydeficitsandheightenedsensitivitytosensorystimuli,includingsound(hyperacusis).ThemolecularbasisoffragileXsyndromeisthoroughlyunderstood;however,theneuralmechanismsunderlyinghyperacusishavenotyetbeendetermined.Astheinferiorcolliculus(IC)istheprincipalmidbrainnucleusoftheauditorypathway,thecurrentstudyaddressesthequestionsunderlyingtheneuralmechanismofhyperacusiswithintheICoffragileXmice.AcuteexperimentswereperformedinwhichelectrophysiologicalrecordingsoftheICinFMR1-KOandWTmiceweremeasured.ResultsshowedthatQ-valuesforWTweresignificantlylargerthanthatofFMR-1KOmice,indicatingthatWTmiceexhibitsharpertuningcurvesthanFMR1-KOmice.WealsofoundtheratioofthemonotonicneuronsintheKOmicewasmuchhigherthantheWTmice.TheseresultssuggestthatlackofFMRPintheauditorysystemaffectsthedevelopmentalmaturationandfunctionofstructureswithintheauditorypathway,andinthiscasespecificallytheIC.ThedysfunctionobservedwithintheauditoryneuralpathwayandinparticulartheICmayberelatedtotheincreasedsusceptibilitytosoundasseeninindividualswithfragileXsyndrome.OurstudymayhelponunderstandingthemechanismsofthefragileXsyndromeandhyperacusis.
简介:Durationisasalientfeatureofacousticsignalsincludingspeech.Durationtuningwasfirstreportedinfrogsandlaterinecholocatingbats.Morerecently,durationtuninghasbeenreportedinnon-echolocatingmammalsandappearstobeafundamentalencodingmechanismthroughouttheanimalkingdom.However,thedurationtuningreportedinthesenon-echolocatingmammalsappearstobemuchweakerthanthatinthepreviousstudiesonbats.Incontrasttothisfinding,ourrecentstudyreportedthatdurationtuningintheICinguineapigsappearedtobestrongwhenitwasmeasuredusinganappropriatetemporalwindow.Withsuchatemporalwindow,durationtuningwasfoundtobecompatiblewiththatofecho-locatingbats.Inthepresentreport,wefurtherdemonstratethatdurationtuningintheICofthisspeciesisestablishedbyinteractionbetweenexcitationandGABAergicinhibition.Inadditiontooverallincreaseinresponsiveness,applicationofbicuculline(BIC),aGABA-Areceptorantagonist,wasfoundtosignificantlyreduceoreliminatedurationselectivityin44outofthe67neuronsthatshowedcleardurationtuningfromasampleof340neurons.