北大神经生物学7-1神经系统对运动的调节课件

CentralNervousSystemControlofMovement,XING,GUOGANG(邢国刚),MD.Ph.D.NeuroscienceResearchInstitute,PekingUniversityEmailaddress:,1,PPT学习交流,Introduction,生命在于运动运动是动物维系个体生存和种族繁衍的基本功能之一,2,PPT学习交流,Howdoesacoordinatedmovementachieved?,3,PPT学习交流,Thementalbodyimageseemstobegeneratedbysomatosensory,proprioceptive,andvisualinputstotheposteriorparietalcortex(area5,area7),Abaseballpitcherplanningapitch,4,PPT学习交流,ThehighestlevelstrategyRepresentedbytheassociationareasofneocortexandbasalgangliaoftheforebrainIsconcernedwithstrategy:Thegoalofthemovementandthemovementstrategythatbestachievesthegoal,Themotorcontrolhierarchyhavethreelevels,5,PPT学习交流,ThemiddleleveltacticsRepresentedbythemotorcortexandcerebellumIsconcernedwithtacticsThesequencesofmusclecontractionsArrangedinspaceandtimeRequiredtosmoothlyandaccuratelyachievethestrategicgoal,Themotorcontrolhierarchyhavethreelevels,6,PPT学习交流,ThelowestlevelexecutionRepresentedbythebrainstemandspinalcordIsconcernedwithexecutionActionofthemotorneuronandinterneuronpoolsthatgeneratethegoal-directedmovementandmakeanynecessaryadjustmentsofposture,Themotorcontrolhierarchyhavethreelevels,7,PPT学习交流,Overview,脊髓内的“下运动神经元(Lowerneurons)”，除了受到脊髓内局部环路的影响外，还受到大脑皮层运动区及脑干中许多“上运动神经元(Upperneurons)”的支配和协调基底神经节和小脑则向那些上运动神经元提供某种感觉、认知或感性的信息，使运动更加精确和协调,8,PPT学习交流,9,PPT学习交流,Theseprogramsareaccessed,executed,andmodifiedbydescendingcommandsfromthebrain,Thebrainscommandandcontrolofthemotorprogramsinthespinalcord,Themotorsystemconsistsofallourmusclesandtheneuronsthatcommandthem,Thespinalcordcontainscertainmotorprogramsforthegenerationofcoordinatedmovements,Themotorcontrolcanbedividedintotwoparts:,Thespinalcordscommandandcontrolofcoordinatedmusclecontraction,10,PPT学习交流,Part1SpinalControlofMovement,11,PPT学习交流,Introduction,“runningaroundlikeachickenwithitsheadcutoff”TherhythmicmovementscouldbeelicitedinthehindlegsofcatsanddogslongaftertheirspinalcordshadbeenseveredfromtherestofthecentralnervoussystemCharlesSheringtonbehaviorAcompletetransectionofacatsspinalcordatthemid-thoraciclevelleavesthehindlimbscapableofgeneratingcoordinatedwalkingmovements,Whenyouwalk,youalternatelywithdrawandextendyourtwolegsWhatisthemechanismtocoordinatethetiming?,Thiscouldbedescendingcommandsfromuppermotorneurons?,No!,Thiscontrolisexertedfromwithinthespinalcord?,Yes!,41,PPT学习交流,42,PPT学习交流,Centralpatterngeneratorswithinthespinalcord,ThecircuitforthecoordinatedcontrolofwalkingmustresidewithinthespinalcordIngeneral,circuitsthatgiverisetorhythmicmotoractivityarecalledcentralpatterngeneratorsHowdoneuralcircuitsgeneraterhythmicpatternsofactivity?Thesimplestpatterngenerators,aresingleneuronswhosemembranepropertiesendowthemwithpacemakerproperties(pacemakerneurons),43,PPT学习交流,Rhythmicactivityinaspinalinterneuron(Pacemakerneuron),SomeneuronsrespondtotheactivationofNMDAreceptorswithrhythmicdepolarization,44,PPT学习交流,Apossiblecircuitforrhythmicalternatingactivity(walking),Walkingisinitiatedwhenasteadyinputexcitestwointerneuronsthatconnecttothemotorneuronscontrollingtheflexorsandextensors,respectively.Theinterneuronsrespondtoacontinuousinputbygeneratingburstsofoutputs.Theactivitiesofthetwointerneuronsalternatebecausetheyinhibiteachotherviaother(inhibitory)interneurons.Thus,aburstofactivityinoneinterneuronstronglyinhibitstheother,(Pacemakerneuron),(Pacemakerneuron),45,PPT学习交流,Part2BrainControlofMovement,46,PPT学习交流,Howdoesthebraincommunicatewiththemotorneuronsofthespinalcord?,47,PPT学习交流,Overview,来自高级中枢的下行投射对脑干和脊髓环路的运动控制主要影响随意运动和朝向目标的运动发出下行投射的中枢位于脑干某些部位以及大脑皮质的运动区域脑干内的两个主要结构前庭核和网状结构对维持姿势很重要皮质主要运动区和次要运动区(运动前区)主要对运动进行计划并使运动高效率执行，皮质的这种作用是通过对脑干内的某些高级中枢以及脑干、脊髓中运动神经元和环路中间神经元的控制来完成的,48,PPT学习交流,Thedescendingspinaltractscontrolofmovement,49,PPT学习交流,Thedescendingspinaltracts,50,PPT学习交流,Controlfinemovementsofthearmsandfingers,Theeffectsoflateralpathwaylesions(inmonkeys)byDonaldLawrence&HansKuypers(inthelate1960s),TheLateralPathways,X,51,PPT学习交流,TheVentromedialPathways,ContainfourdescendingtractsthevestibulospinaltractthetectospinaltractthepontinereticulospinaltractthemedullaryreticulospinaltractOringinateinthebrainstemTerminateamongthespinalinterneuronsControllingproximalandaxialmusclesUsesensoryinformationaboutbalance,bodyposition,andthevisualenviromenttoreflexivelymaintainbalanceandbodyposture,52,PPT学习交流,Thevestibulospinalandtectospinaltractskeeptheheadbalanceontheshouldersasthebodymovesthroughspace,andtheyturntheheadinresponsetonewsensorystimuli,(midbrain),RecivedirectinputfromretinaReciveprojectionsfromvisualcortex,aswellasafferentscarringsomatosensoryandauditoryinformationConstructamapofthewordaroundus,Themotionofthefluidinthislabyrinth,whichaccompaniesmovementsofthehead,activateshaircellsthatsignalthevestibularnucleiviacranialnerveVIII,One:Projectsbilaterallydownthespinalcordandactivatesthecervicalspinalcircuitsthatcontrolneckandbackmusclesandguidheadmovement,Another:ProjectsipsilaterallyasfardownasthelumbarspinalcordIthelpsusmaintainanuprightandbalancedposturebyfacilitatingextensormotorneuronsofthelegs,StimulationatonesiteinthismapLeadtoanorientingresponsethatdirectstheheadandeyestomove,53,PPT学习交流,ThepontinereticulospinaltractenhancetheantigravityreflexesofthespinalcordByfacilitatingtheextensorsofthelowerlimbsHelpsmaintainastandingposturebyresistingtheeffectsofgravity,Themedullaryreticulospinaltracthastheoppositeeffect:itliberatestheantigravitymusclesfromreflexcontrol,ActivityinbothreticulospinaltractsiscontrolledbydescendingsignalsfromthecortexControlpostureofthetrunkandtheantigravitymusclesofthelimbs,54,PPT学习交流,Asummaryofthemajordescendingspinaltractsandtheirpointsoforigin,MotorcortexdirectlyactivatesspinalmotorneuronsandliberatesthemfromreflexcontrolbycommunicatingwiththenucleioftheventromedialpathwaysSo,thecortexiskeyforvolunt