北大神经生物学课件7-1神经系统对运动的调节

1CentralNervousSystemControlofMovementXING,GUOGANG(邢国刚),MD.Ph.D.北京大学神经科学研究所NeuroscienceResearchInstitute,PekingUniversityEmailaddress:[e-mail]2Introduction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一3Howdoesacoordinatedmovementachieved?4Thementalbodyimageseemstobegeneratedbysomatosensory,proprioceptive,andvisualinputstotheposteriorparietalcortex(area5,area7)Abaseballpitcherplanningapitch…5Thehighestlevel－strategyRepresentedbytheassociationareasofneocortexandbasalgangliaoftheforebrainIsconcernedwithstrategy:—ThegoalofthemovementandthemovementstrategythatbestachievesthegoalThemotorcontrolhierarchyhavethreelevels6Themiddlelevel－tacticsRepresentedbythemotorcortexandcerebellumIsconcernedwithtactics—Thesequencesofmusclecontractions•Arrangedinspaceandtime•RequiredtosmoothlyandaccuratelyachievethestrategicgoalThemotorcontrolhierarchyhavethreelevels7Thelowestlevel－executionRepresentedbythebrainstemandspinalcordIsconcernedwithexecution—Actionofthemotorneuronandinterneuronpoolsthatgeneratethegoal-directedmovementandmakeanynecessaryadjustmentsofpostureThemotorcontrolhierarchyhavethreelevels8Overview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910SensorimotorcortexBasalgangliaCerebellumBrainstemSpinalcordInterneuron-MotorneuronMotorunit(finalcommonpathway)Receptorsmuscle,skin,joint12345Theseprogramsareaccessed,executed,andmodifiedbydescendingcommandsfromthebrainThebrain’scommandandcontrolofthemotorprogramsinthespinalcordThemotorsystemconsistsofallourmusclesandtheneuronsthatcommandthemThespinalcordcontainscertainmotorprogramsforthegenerationofcoordinatedmovementsThemotorcontrolcanbedividedintotwoparts:Thespinalcord’scommandandcontrolofcoordinatedmusclecontraction11Part1SpinalControlofMovement12Introduction“runningaroundlikeachickenwithitsheadcutoff”Therhythmicmovementscouldbeelicitedinthehindlegsofcatsanddogslongaftertheirspinalcordshadbeenseveredfromtherestofthecentralnervoussystem–CharlesSherington&GrahamBrown(English)—Theimportanceofcircuitrywithinthespinalcordforthecoordinatedcontrolofmovements13Spinalcircuitrycontrolofmovement14SpinalmotorneuronsAlphamotorneuronsInnervateskeletalmuscle(extrafusalmuscle)Function:directlycommandmusclecontractGammamotorneuronsInnervatemusclespindle(intrafusalmuscle)Function:regulatingthemusclespindleInterneuronsAllowscoordinatedmotorprogramstobegeneratedFinalcommonpathway(directlycommandmusclecontract)•Compare:UppermotorneuronsLowermotorneurons15TheLowerMotorNeurons－AlphamotorneuronsAlphamotorneuronsaredirectlyresponsibleforthegenerationofforcebymuscleMotorunit:onealphamotorneuronandallofthemusclefibersitinnervatescollectivelymakeupmotorunit,theelementarycomponentofmotorcontrolMotorneuronpool:Thecollectionofalphamotorneuronsthatinnervatesasinglemuscle16ThemotorunitisanalphamotorneuronandallofthemuscleAmotorunitandmotorneuronpoolThemotorneuronpoolisallofthealphamotorneuronsthatinnervateonemuscle17Muscleinnervationbylowermotorneurons30mixedspinalnervescervical1-8thoracic1-12lumbar1-5sacral1-5TheventralhornofthespinalcordcontainsmotorneuronsthatinnervateskeletalmusclefibersVentralroots+Dorsalroot=Spinalnerve18ThecervicalenlargementofthespinalcordcontainsthemotorneuronsthatinnervatethearmmusclesThelumbarenlargementcontainsneuronsthatinnervatethemusclesoftheleg支配上肢的神经元集群位于颈膨大处，支配下肢的则在腰膨大处ThedistributionofmotorneuronsinthespinalcordThemotorneuronsthatinnervatedistalandproximalmusculaturearefoundmainlyinthecervicalandlumbar-sacralsegmentsofthespinalcordWhereasthoseinnervatingaxialmusculaturearefoundatalllevelsSegmentsC3-T1haveaswollenventralhornthatinnervateskeletalmusculatureinarmsSegmentsL1-S3haveaswollenventralhornthatinnervateskeletalmusculatureinlegs19MotorneuronscontrollingflexorsliedorsaltothosecontrollingextensorsMotorneuronscontrollingaxialmusclesliemedialtothosecontrollingdistalmuscles支配躯干部肌肉的神经元位于脊髓前角灰质最内侧，由此向外排列的神经元则支配肢体由近及远分布的肌肉Thedistributionoflowermotorneuronsintheventralhorn20Muscleweaknessandparalysis－所支配的骨骼肌瘫痪、肌张力下降、腱反射消失(软瘫)肌萎缩、纤维颤动或肌束颤动见于如肌萎缩侧索硬化症(amyotrophiclateralsclerosis,ALS)：Selectivedamagetoalphamotorneurons(degeneration)－脊髓-运动神经元的进行性溃变为主下运动神经元的损伤表现21LouGehrigFarewellSpeech:Fans,forthepasttwoweeksyouhavebeenreadingaboutthebadbreakIgot.YettodayIconsidermyselftheluckiestmanonthefaceofthisearth.……SoIcloseinsayingthatImayhavehadatoughbreak,butIhaveanawfullottolivefor.LouGehring,astarbaseballplayerwithNewYorkYankees,whodiedofALS(amyotrophiclateralsclerosis)in193622InputstoalphamotorneuronsThisinputisimportantfortheinitiationandcontrolofvoluntarymovementThisinputmaybeexcitatoryorinhibitoryandispartofthecircuitrythatgeneratesthespinalmotorprogramsThisinputprovidesfeedbackaboutmusclelength23SPINALCONTROLOFMOTORUNITSHowtheactivityofthemotorneuronisitselfcontrolled?24ReflexReceptorEffectorSpinalMotorNeuron(center)SkinMuscleJointMusclecontractionHigherCenter•Voluntarymovements•Nociceptivestimulus•Stretchmuscles•Posturemaintenance25Themyotaticreflex(stretchreflex)