北大神經(jīng)生物學課件神經(jīng)系統(tǒng)對運動的調(diào)節(jié)

CentralNervousSystemControlofMovementXING,GUOGANG(邢國剛),MD.Ph.D.北京大學神經(jīng)科學研究所NeuroscienceResearchInstitute,PekingUniversity當前1頁，總共112頁。1Introduction生命在于運動……運動是動物維系個體生存和種族繁衍的基本功能之一當前2頁，總共112頁。2Howdoesacoordinatedmovementachieved?當前3頁，總共112頁。3Thementalbodyimageseemstobegeneratedbysomatosensory,proprioceptive,andvisualinputstotheposteriorparietalcortex(area5,area7)Abaseballpitcherplanningapitch…當前4頁，總共112頁。4Thehighestlevel－

strategyRepresentedbytheassociationareasofneocortexandbasalgangliaoftheforebrainIsconcernedwithstrategy:ThegoalofthemovementandthemovementstrategythatbestachievesthegoalThemotorcontrolhierarchyhavethreelevels當前5頁，總共112頁。5Themiddlelevel－tacticsRepresentedbythemotorcortexandcerebellumIsconcernedwithtacticsThesequencesofmusclecontractionsArrangedinspaceandtimeRequiredtosmoothlyandaccuratelyachievethestrategicgoalThemotorcontrolhierarchyhavethreelevels當前6頁，總共112頁。6Thelowestlevel－

execution

RepresentedbythebrainstemandspinalcordIsconcernedwithexecutionActionofthemotorneuronandinterneuronpoolsthatgeneratethegoal-directedmovementandmakeanynecessaryadjustmentsofpostureThemotorcontrolhierarchyhavethreelevels當前7頁，總共112頁。7Overview脊髓內(nèi)的“下運動神經(jīng)元(Lowerneurons)”，除了受到脊髓內(nèi)局部環(huán)路的影響外，還受到大腦皮層運動區(qū)及腦干中許多“上運動神經(jīng)元(Upperneurons)”的支配和協(xié)調(diào)基底神經(jīng)節(jié)和小腦則向那些上運動神經(jīng)元提供某種感覺、認知或感性的信息，使運動更加精確和協(xié)調(diào)當前8頁，總共112頁。8當前9頁，總共112頁。9SensorimotorcortexBasalgangliaCerebellumBrainstemSpinalcordInterneuron-MotorneuronMotorunit(finalcommonpathway)Receptorsmuscle,skin,joint12345Theseprogramsareaccessed,executed,andmodifiedbydescendingcommandsfromthebrainThebrain’scommandandcontrolofthemotorprogramsinthespinalcordThemotorsystemconsistsofallourmusclesandtheneuronsthatcommandthemThespinalcordcontainscertainmotorprogramsforthegenerationofcoordinatedmovementsThemotorcontrolcanbedividedintotwoparts:Thespinalcord’scommandandcontrolofcoordinatedmusclecontraction當前10頁，總共112頁。10Part1

SpinalControlofMovement當前11頁，總共112頁。11Introduction“runningaroundlikeachickenwithitsheadcutoff”

Therhythmicmovementscouldbeelicitedinthehindlegsofcatsanddogslongaftertheirspinalcordshadbeenseveredfromtherestofthecentralnervoussystem–CharlesSherington&GrahamBrown(English)Theimportanceofcircuitrywithinthespinalcordforthecoordinatedcontrolofmovements當前12頁，總共112頁。12Spinalcircuitry

controlofmovement當前13頁，總共112頁。13Spinalmotorneurons

Alphamotorneurons

Innervateskeletalmuscle(extrafusalmuscle)

Function:directlycommandmusclecontractGammamotorneurons

Innervatemusclespindle(intrafusalmuscle)

Function:regulatingthemusclespindleInterneurons

AllowscoordinatedmotorprogramstobegeneratedFinalcommonpathway(directlycommandmusclecontract)Compare:

UppermotorneuronsLowermotorneurons當前14頁，總共112頁。14TheLowerMotorNeurons

－AlphamotorneuronsAlphamotorneuronsaredirectlyresponsibleforthegenerationofforcebymuscleMotorunit:onealphamotor

neuronandallofthemusclefibersitinnervatescollectivelymakeupmotorunit,theelementarycomponentofmotorcontrolMotorneuronpool:Thecollectionofalphamotorneuronsthatinnervatesasinglemuscle當前15頁，總共112頁。15ThemotorunitisanalphamotorneuronandallofthemuscleAmotorunitandmotorneuronpoolThemotorneuronpoolisallofthealphamotorneuronsthatinnervateonemuscle當前16頁，總共112頁。16Muscleinnervationbylowermotorneurons30mixedspinalnervescervical1-8thoracic1-12lumbar1-5sacral1-5TheventralhornofthespinalcordcontainsmotorneuronsthatinnervateskeletalmusclefibersVentralroots+Dorsalroot=Spinalnerve當前17頁，總共112頁。17Thecervicalenlargementofthespinalcordcontainsthemotorneuronsthatinnervatethearmmuscles

Thelumbarenlargementcontainsneuronsthatinnervatethemusclesoftheleg

支配上肢的神經(jīng)元集群位于頸膨大處，支配下肢的則在腰膨大處ThedistributionofmotorneuronsinthespinalcordThemotorneuronsthatinnervatedistalandproximalmusculaturearefoundmainlyinthecervicalandlumbar-sacralsegmentsofthespinalcordWhereasthoseinnervatingaxialmusculaturearefoundatalllevelsSegmentsC3-T1haveaswollenventralhornthatinnervateskeletalmusculatureinarmsSegmentsL1-S3haveaswollenventralhornthatinnervateskeletalmusculatureinlegs當前18頁，總共112頁。18Motorneuronscontrollingflexorsliedorsaltothosecontrollingextensors

Motorneuronscontrollingaxialmusclesliemedialtothosecontrollingdistalmuscles支配軀干部肌肉的神經(jīng)元位于脊髓前角灰質(zhì)最內(nèi)側(cè)，由此向外排列的神經(jīng)元則支配肢體由近及遠分布的肌肉Thedistributionoflowermotorneuronsintheventralhorn當前19頁，總共112頁。19Muscleweaknessandparalysis－所支配的骨骼肌癱瘓、肌張力下降、腱反射消失(軟癱)肌萎縮、纖維顫動或肌束顫動見于如肌萎縮側(cè)索硬化癥(amyotrophiclateralsclerosis,

ALS)：Selectivedamagetoalphamotorneurons(degeneration)－脊髓-運動神經(jīng)元的進行性潰變?yōu)橹飨逻\動神經(jīng)元的損傷表現(xiàn)當前20頁，總共112頁。20LouGehrigFarewellSpeech:"Fans,forthepasttwoweeksyouhavebeenreadingaboutthebadbreakIgot.YettodayIconsidermyselftheluckiestmanonthefaceofthisearth.……SoIcloseinsayingthatImayhavehadatoughbreak,butIhaveanawfullottolivefor."LouGehring,astarbaseballplayerwithNewYorkYankees,whodiedofALS(amyotrophiclateralsclerosis)in1936當前21頁，總共112頁。21InputstoalphamotorneuronsThisinputisimportantfortheinitiationandcontrolofvoluntarymovementThisinputmaybeexcitatoryorinhibitoryandispartofthecircuitrythatgeneratesthespinalmotorprogramsThisinputprovidesfeedbackaboutmusclelength當前22頁，總共112頁。22SPINALCONTROLOFMOTORUNITSHowtheactivityofthemotorneuronisitselfcontrolled?當前23頁，總共112頁。23ReflexReceptorEffectorSpinalMotorNeuron(center)SkinMuscleJointMusclecontractionHigherCenterVoluntarymovementsNociceptivestimulusStretchmusclesPosturemaintenance當前24頁，總共112頁。24Themyotaticreflex(stretchreflex)Twotypesofmyotaticreflex

－TendonreflexandmuscletonusA.Tendonreflex

—快速牽拉肌腱而發(fā)生的牽張反射Clinicapplication：了解脊髓不同節(jié)段的功能狀態(tài)

單突觸反射潛伏期很短，約0.7s只夠一次突觸傳遞時間延擱當前25頁，總共112頁。25+當前26頁，總共112頁。26B.Muscletonus

肌肉受到緩慢而持續(xù)的牽拉而發(fā)生的收縮－使骨骼肌能保持一定的肌肉張力意義:維持身體的姿勢(posture)，而不表現(xiàn)明顯的動作表現(xiàn)：extensor(伸肌)和flexor(屈肌)都發(fā)生肌緊張直立時，以伸肌緊張為主，因重力作用于關(guān)節(jié)，使關(guān)節(jié)趨向彎曲，伸肌受到牽拉，引起肌緊張反射，肌緊張度增加以對抗關(guān)節(jié)屈曲因重力持續(xù)作用于關(guān)節(jié)，肌緊張也就持續(xù)發(fā)生。使直立姿勢得以維持多突觸反射潛伏期較長，經(jīng)過多個突觸傳遞當前27頁，總共112頁。27

Musclespindles:ConsistsofspecializedskeletalmusclefibersInthismiddleregion,groupIa

sensoryaxonswraparoundthemusclefibersofthespindleThespindlesandtheirassociatedIaaxons,specializedforthedetectionofchangesinmusclelength(stretch):proprioceptorsandpropriceptionIaaxonsarethethickestmyelinatedaxonssotheyconductactionpotentialsveryrapidlyIaaxonsenterthespinalcordviathedorsalroots,branchrepeatedly,andformexcitatorysynapsesuponbothinterneuronsandalphamotorneuronsoftheventralhornsProprioceptionfrommusclespindlesMusclespindle

是一種可感受肌肉長度變化或感受牽拉刺激的本體感受器梭內(nèi)肌感受部裝置位于中間,收縮成分位于兩端,梭內(nèi)肌收縮時或牽拉梭外肌時,感受裝置對牽拉敏感性增高

當前28頁，總共112頁。28+當前29頁，總共112頁。29GammamotorneuronsExtrafusalfibersareinnervatedbyalphamotorneuronsIntrafusalfibersreceivetheirmotorinnervationbyanothertypeoflowermotorneuroncalledagammamotorneuronGammamotorneuronsinnervatetheintrafusalmusclefiberatthetwoendsofthemusclespindleActivationofthesefiberscausesacontractionofthetwopolesofthemusclespindle,therebypullingonthenon-contractileequatorialregionandkeepingtheIaafferentsactive當前30頁，總共112頁。30ThefunctionofgammamotorneuronsActivationofalphamotorneuronsshortenstheextrafusalmusclefibers.Ifthemusclespindlebecomesslack,itgoes“offtheair”andnolongerreportsthelengthofthemuscleActivationofgammamotorneuronscontractsthepolesofthespindle,keepingit“ontheair”當前31頁，總共112頁。31TheGammaloopChangingtheactivityofthegammamotorneuronschangesthesetpointofthemyotaticfeedbackloopTheGammaloopGammamotorneuronintrafusalmusclefiberIaafferentalphamotorneuronextrafusalmusclefibersAlphaandgammamotorneuronsaresimultaneouslyactivatedbydescendingcommandsfromthebrain當前32頁，總共112頁。32ProprioceptionfromGolgitendonorgansGolgitendonorganActslikeastraingauge,itmonitorsmuscletension,ortheforceofcontractionLocatedatthejunctionofthemuscleandthetendonandareinnervatedbygroupIbsensoryaxonsthatareslightlysmallerthantheIaaxonsinnervatingthemusclespindles當前33頁，總共112頁。33GolgitendonorgansrespondtoincreasedtensiononthemuscleandtransmitthisinformationtothespinalcordviatypeIbsensoryafferents.Becausetheactivatedmuscledoesnotchangelength,theIaafferentsremainsilentinthisexample當肌肉等長收縮時,腱器官傳入沖動頻率,肌梭傳入沖動頻率不變;當肌肉等張收縮時,腱器官傳入沖動頻率不變,肌梭傳入沖動頻率Golgitendon

organslieinseriesbetweenthemusclefibersandtheirpointsofattachmentMusclespindlesarearrangedparalleltotheextrafusalfibers當前34頁，總共112頁。34TheIbafferentsenterthespinalcord,branchrepeatedly,andsynapseoninterneuronsintheventralhornSomeoftheseinterneuronsforminhibitoryconnectionswiththealphamotorneuronsinnervatingthesamemuscle.ThisisthebasisforthereversemyotaticreflexCircuitryofthereversemyotaticreflex＋-Musclespindlesituatedinparallelwiththemusclefibers,GolgitendonorgansaresituatedinseriesIaactivityfromthespindleencodesmusclelengthinformationWhileIbactivityfromtheGolgitendonorganencodesmuscletensioninformation腱器官是張力感受器,其傳入沖動對同一肌肉運動神經(jīng)元起抑制作用肌梭是長度感受器,其傳入沖動對同一肌肉運動神經(jīng)元起興奮作用當肌肉被動牽拉時,二者傳入沖動頻率均：首先興奮肌梭發(fā)動牽張反射,肌肉收縮,牽拉力大到一定程度,興奮腱器官而抑制牽張反射牽張反射的特點：反射弧簡單，感受器和效應(yīng)器在同一塊肌肉當前35頁，總共112頁。35SignificanceofthereversemyotaticreflexInextremecircumstances,thisreflexarcprotectsthemusclefromoverloadThenormalfunctionistoregulatemuscletensionwithinanoptimalrangeAsmuscletension

increases,theinhibitionofthealphamotorneuronslowsmusclecontractionAsmuscletensionfalls,theinhibitionofthealphamotorneuronisreduced,andmusclecontractionincreasesThistypeofproprioceptivefeedbackisthoughttobeparticularlyimportantfortheproperexecutionoffinemotoracts,suchasthemanipulationoffragileobjectswiththehands,whichrequireasteadybutnottoopowerfulgrip當前36頁，總共112頁。36SpinalinterneuronsMostoftheinputtothealphamotorneuronscomesfrominterneuronsofthespinalcordInterneuronsreceivesynapticinputfromprimarysensoryaxons,descendingaxonsfromthebrain,andcollateralsoflowermotorneuronaxonsTheinterneuronsarethemselvesnetworkedtogetherinawaythatallowscoordinatedmotorprogramstobegeneratedinresponsetotheirmanyinputs當前37頁，總共112頁。37Reciprocalinhibitionofflexorsandextensorsofthesamejoint+++-InhibitoryinputContractionofonesetofmusclesaccompaniedbytherelaxationoftheantagonistmusclesiscalled

reciprocalinhibitionReciprocalinhibitionisalsousedbydescendingpathwaystoovercomethepowerfulmyotaticreflex當前38頁，總共112頁。38(A

&Cfibers)ExcitatoryinputFlexorreflex:usedtowithdrawalimbfromanaversivestimulus,suchasthewithdrawalofyourfootfromthethumbtackThepainfibersenteringthespinalcordbranchprofusedlyandactivateinterneuronsinseveralspinalsegments.Thesecellseventuallyexcite

thealphamotorneuronsthatcontrolalloftheflexormusclesoftheaffectedlimb(andinhibitoryinterneuronsarealsorecruitedtoinhibitthealphasthatcontroltheextensors)++++Circuitryofthepolysynapticflexorreflex當前39頁，總共112頁。39Circuitryofthecrossed-extensorreflexSpinalcordIpsilateralextensorsinhibitedContralateralextensorsactivated(contract)Ipsilateralflexorsactivated(contract)ContralateralflexorsinhibitedIpsilateralkneejointclosesuptoremovefootfromtackContralateralkneejointopensuptosupportgreaterweight當前40頁，總共112頁。40ThegenerationofspinalmotorprogramsforwalkingHeadlesschickens;behaviorAcompletetransectionofacat’sspinalcordatthemid-thoraciclevelleavesthehindlimbscapableofgeneratingcoordinatedwalkingmovementsWhenyouwalk,youalternatelywithdrawandextendyourtwolegs

Whatisthemechanismtocoordinatethetiming?Thiscouldbedescendingcommandsfromuppermotorneurons?No!Thiscontrolisexertedfromwithinthespinalcord?Yes!當前41頁，總共112頁。41當前42頁，總共112頁。42CentralpatterngeneratorswithinthespinalcordThecircuitforthecoordinatedcontrolofwalkingmustresidewithinthespinalcordIngeneral,circuitsthatgiverisetorhythmicmotoractivityarecalledcentralpatterngenerators

Howdoneuralcircuitsgeneraterhythmicpatternsofactivity?Thesimplestpatterngenerators,aresingleneuronswhosemembranepropertiesendowthemwithpacemakerproperties(pacemakerneurons)當前43頁，總共112頁。43Rhythmicactivityinaspinalinterneuron(Pacemakerneuron)SomeneuronsrespondtotheactivationofNMDAreceptorswithrhythmicdepolarization(a)Intherestingstate,theNMDAreceptorchannelsandthecalcium-activatedpotassiumchannelsareclosed(b)GlutamatecausestheNMDAreceptorstoopen,thecellmembranetodepolarize,andCa2+ionstoenterthecell(c)Theriseinintracellular[Ca2+]causestheCa2+-activatedpotassiumchannelstoopen.K+ionsleavetheneuron,hyperpolarizingthemembrane.ThehyperpolarizationallowsMg2+ionstoenterandclogtheNMDAchannel,arrestingtheflowofCa2+(d)As[Ca2+]falls,thepotassiumchannelsclose,resettingthemembraneforanotheroscillation當前44頁，總共112頁。44Apossiblecircuitforrhythmicalternatingactivity(walking)Walkingisinitiatedwhenasteadyinputexcitestwointerneuronsthatconnecttothemotorneuronscontrollingtheflexorsandextensors,respectively.Theinterneuronsrespondtoacontinuousinputbygeneratingburstsofoutputs.Theactivitiesofthetwointerneuronsalternatebecausetheyinhibiteachotherviaother(inhibitory)interneurons.Thus,aburstofactivityinoneinterneuronstronglyinhibitstheother(Pacemakerneuron)(Pacemakerneuron)當前45頁，總共112頁。45Part2

BrainControlofMovement當前46頁，總共112頁。46Howdoesthebraincommunicatewiththemotorneuronsofthespinalcord?當前47頁，總共112頁。47Overview來自高級中樞的下行投射對腦干和脊髓環(huán)路的運動控制主要影響隨意運動和朝向目標的運動發(fā)出下行投射的中樞位于腦干某些部位以及大腦皮質(zhì)的運動區(qū)域腦干內(nèi)的兩個主要結(jié)構(gòu)－前庭核和網(wǎng)狀結(jié)構(gòu)對維持姿勢很重要皮質(zhì)主要運動區(qū)和次要運動區(qū)(運動前區(qū))主要對運動進行計劃并使運動高效率執(zhí)行，皮質(zhì)的這種作用是通過對腦干內(nèi)的某些高級中樞以及腦干、脊髓中運動神經(jīng)元和環(huán)路中間神經(jīng)元的控制來完成的當前48頁，總共112頁。48Thedescendingspinaltractscontrolofmovement當前49頁，總共112頁。49ThedescendingspinaltractsControlpostureandunderbrainstemcontrolContolvoluntary

movementsofthedistalmusculatureandunderdirectcorticalcontrol當前50頁，總共112頁。50(Pyramidaltract)ControlfinemovementsofthearmsandfingersTheeffectsoflateralpathwaylesions(inmonkeys)－byDonaldLawrence&HansKuypers(inthelate1960s)TheLateralPathwaysXJoinincorticospinaltractinthelateralcolumnofthespinalcordTerminateinthedorsolateralregionoftheventralhornsandintermedialgraymatterWheremotorneuronsandinterneuronscontrolthedistalmuscles,particularlyflexorsInputfromfrontalcortexX當前51頁，總共112頁。51TheVentromedialPathwaysContainfourdescendingtracts

thevestibulospinaltractthetectospinaltractthepontinereticulospinaltractthemedullaryreticulospinaltract

Oringinateinthebrainstem

TerminateamongthespinalinterneuronsControllingproximalandaxialmusclesUsesensoryinformationaboutbalance,bodyposition,andthevisualenviromenttoreflexivelymaintainbalanceandbodyposture當前52頁，總共112頁。52Thevestibulospinalandtectospinaltractskeeptheheadbalanceontheshouldersasthebodymovesthroughspace,andtheyturntheheadinresponsetonewsensorystimuli(midbrain)RecivedirectinputfromretinaReciveprojectionsfromvisualcortex,aswellasafferentscarringsomatosensoryandauditoryinformationConstructamapofthewordaroundusThemotionofthefluidinthislabyrinth,whichaccompaniesmovementsofthehead,activateshaircellsthatsignalthevestibularnucleiviacranialnerveVIIIOne:ProjectsbilaterallydownthespinalcordandactivatesthecervicalspinalcircuitsthatcontrolneckandbackmusclesandguidheadmovementRelysensoryinformationfromthevestibularlabyrinthintheinnerearAnother:ProjectsipsilaterallyasfardownasthelumbarspinalcordIthelpsusmaintainanuprightandbalancedposturebyfacilitatingextensormotorneuronsofthelegsStimulationatonesiteinthismapLeadtoanorientingresponsethatdirectstheheadandeyestomove…當前53頁，總共112頁。53ThepontinereticulospinaltractenhancetheantigravityreflexesofthespinalcordByfacilitatingtheextensorsofthelowerlimbsHelpsmaintainastandingposturebyresistingtheeffectsofgravityThemedullaryreticulospinaltracthastheoppositeeffect:itliberatestheantigravitymusclesfromreflex

controlActivityinbothreticulospinaltractsiscontrolledbydescendingsignalsfromthecortexControlpostureofthetrunkandtheantigravitymusclesofthelimbs當前54頁，總共112頁。54AsummaryofthemajordescendingspinaltractsandtheirpointsoforiginMotorcortexdirectlyactivatesspinalmotorneuronsandliberatesthemfromreflexcontrolbycommunicatingwiththenucleioftheventromedialpathwaysSo,thecortexiskeyforvoluntarymovementandbehaviorTheventromedialpathwaysoriginatefromseveralregionsofthebrainstemandparticipatemainlyinthemaintenanceofpostureandcertainreflexmovementsInitiationofavoluntarymovements,requiresinstructionsthatdescendfromthemotorcortexalongthelateralpathways當前55頁，總共112頁。55ourattention當前56頁，總共112頁。56MotorCortexMotorCortex(Primarymotorcortex)(Premotorarea)(lateralregion)(Supplementarymotorarea)(medialregion)AreasofneocortexintimatelyinvolvedintheplanningandinstructionofvoluntarymovementThemotorcortexisacircuscribedregionofthefrontallobeArea4liesjustanteriortothecentralsulcusontheprecentralgyrusArea6liesjustanteriortoarea4當前57頁，總共112頁。57當前58頁，總共112頁。58Asomatotopicmap

ofthehumanprecentralgyrus運動皮層對軀體運動的調(diào)控特點：交叉性：但頭面部肌肉的支配是雙側(cè)性的有精細的功能定位：大體呈身體倒影:在4區(qū)內(nèi)側(cè)近中線部位是下肢代表區(qū)，向外側(cè)依次為軀干、前臂、手指，最外側(cè)靠近外側(cè)溝處為面部和舌代表區(qū)頭面代表區(qū)內(nèi)部為正立的運動精細部位其代表區(qū)大：如手指和面部當前59頁，總共112頁。59Area5PosteriorparietalcortexPrefrontalareas:inhumansarethoughttobeimportantforabstractthought,decisionmaking,andanticipatingtheconsequencesofactionArea6and4togethercontributemostoftheaxonstothedescendingcorticospinaltractArea6liesatthejunctionwheresignalsencodingwhatactionsaredesiredareconvertedintosignalsthatspecifyhowtheactionwillbecarriedoutPrefrontalareas,alongwiththeposteriorparietalcortex,representthehighestlevelsofthemotorcontrolhierarchy,wheredecisionsaremadeaboutwhatactionstotakeandtheirlikelyoutcomeBoththeprefrontalandtheparietalcortexsendaxonsthatconvergeoncorticalarea6Area5,receivesinputsfromprimarysomatosensorycorticalarea3,1,2Area7,receivesinputsfromhigher-ordervisualcorticalareas(MT)ThecontributionsofposteriorparietalandprefrontalcortexPrimarysomatosensorycorticalarea3,1,2Higher-ordervisualcorticalareas(MT)Area7PrefrontalareasForabstractthought,decisionmaking,andanticipatingtheconsequencesofactionArea6Area4Descendingcorticospinaltracts當前60頁，總共112頁。60Theinput-outputorganizationofM1PyramidalcellIncorticallayerV(Motorcortex,M1,Area4)Area6(anterior)Area3,1,2(posterior)Lowermotorneuronsofspinalcord

Thalamus(VLc)CerebellumBrainstemBasalgangliaThalamus(VLo)Somatosensoryinputs當前61頁，總共112頁。61Higher-ordermotorplanningUsingPET(positronemissiontomography)tomonitorchangesinthepatternsofcorticalactivationthataccompanyvoluntarymovementsWhenthesubjectswereaskedtoperformaseriesoffingermovementsfrommemory,thefollowingregionsofcortexshowedincreasedbloodflow:thesomatosensoryandposteriorparietalareas,partsoftheprefrontalcortex(area8),area6,andarea4－PlayaroleingeneratingtheintentiontomoveandconvertingthatintentionintoaplanofactionWhenthesubjectswereaskedonlytorehearsethemovementmentallywithoutactuallymovingthefinger,area6remainedactivebutarea4didnot－PerRolandandhiscolleagues(Danishneurologist)當前62頁，總共112頁。62Thedischargeofacellinthepremotorarea(PMA)beforeamovementArea6(SMAandPMA)playsanimportantroleintheplanningofmovement,particularlycomplexmovementsequencesofthedistalmusculature(a)Ready:Amonkeysitsbeforeapaneloflights.Thetaskistowaitforaninstructionstimulusthatwillinformhimothemovementrequiredtoreceiveajuicereward,thenperformthemovementwhenatriggerstimulusgoeson.TheactivityofaneuroninPMAisrecordedduringthetask(b)Set:theinstructionstimulusoccursatthetimeindicatedbytheupwardarrow,resultinginthedischargeoftheneuroninPMA(c)Go:shortlyafterthemovementisinitiated,thePMAcellceasesfiring當前63頁，總共112頁。63初級運動皮層和前運動區(qū)運動皮層(motorcortex)初級運動皮層(primarymotorarea)，即4區(qū)次級運動區(qū)或稱前運動區(qū)輔助運動區(qū)(supplementarymotorarea)，位于初級運動皮層前面的6區(qū)皮層的內(nèi)側(cè)部分，大部分在大腦半球的內(nèi)側(cè)面外側(cè)前運動區(qū)(lateralpremotorarea)或稱前運動皮層(premotorcortex)，位于6區(qū)的外側(cè)部分當前64頁，總共112頁。64皮層神經(jīng)元運動皮層中的神經(jīng)細胞可分為兩大類錐體細胞，特征是具有向皮層表面伸展的頂樹突。其軸突離開運動皮層到其他皮層或皮層下結(jié)構(gòu)，是主要的傳出神經(jīng)元非錐體細胞，包括星形細胞、籃狀細胞和顆粒細胞，多數(shù)屬于抑制性神經(jīng)元當前65頁，總共112頁。65第Ⅵ層的錐體細胞投射至丘腦，它們也有上行軸突側(cè)支至皮層的各層

皮層各層中錐體細胞的投射第II、III層中的錐體細胞投射至其他皮層區(qū)，位置較淺的細胞投射至同側(cè)皮層(如輔助運動區(qū)、前運動皮層、中央溝后的感覺皮層)，較深的投射至對側(cè)皮層大多數(shù)向皮層下結(jié)構(gòu)的投射起源于第Ⅴ層的錐體細胞，皮層脊髓神經(jīng)元在第Ⅴ層的深部，其中包括最大的錐體細胞即Betz細胞。較淺的第Ⅴ層錐體細胞則投射至延髓、橋腦和紅核，最淺的第Ⅴ層細胞投射至紋狀體當前66頁，總共112頁。66皮層脊髓束和皮層延髓束大腦皮層通過皮層脊髓束和皮層延髓束控制運動皮層延髓束終止于延髓的顱神經(jīng)運動核，控制面部肌肉的活動皮層脊髓束則支配脊髓運動核，控制軀體肌肉的活動當前67頁，總共112頁。67皮層脊髓束和皮層延髓束走行皮層脊髓束和皮層延髓束一起經(jīng)內(nèi)囊下行到中腦腹側(cè)，分散地穿過橋腦核，在延髓集合成錐體繼續(xù)下行至延髓和脊髓交界處，約3/4的纖維交叉至對側(cè)而在脊髓的背外側(cè)束下行，稱為外側(cè)皮層脊髓束，另1/4纖維不交叉而在脊髓腹側(cè)下行，稱為腹側(cè)皮層脊髓束當前68頁，總共112頁。68皮層脊髓束和皮層延髓束走行外側(cè)皮層脊髓束主要終止于脊髓腹角外側(cè)的運動神經(jīng)元和中間區(qū)內(nèi)的中間神經(jīng)元，腹側(cè)皮層脊髓束則主要投射至雙側(cè)腹角腹內(nèi)側(cè)的運動神經(jīng)元和中間區(qū)內(nèi)側(cè)的中間神經(jīng)元，支配軀干中線肌肉和肢體近側(cè)肌肉的皮層延髓束終止于腦干的顱神經(jīng)感覺和運動核當前69頁，總共112頁。69

運動皮層通過兩條獨立的通路分別影響脊髓運動神經(jīng)元一條經(jīng)過錐體束的直接通路直達脊髓灰質(zhì)外側(cè)和內(nèi)側(cè)的運動神經(jīng)元一條間接通路，即經(jīng)過紅核和網(wǎng)狀結(jié)構(gòu)的接替當前70頁，總共112頁。70皮層脊髓纖維和運動神經(jīng)元的聯(lián)系皮層脊髓神經(jīng)元對脊髓的運動神經(jīng)元有直接突觸聯(lián)系，起到強烈的直接興奮性影響皮層脊髓神經(jīng)元間接影響運動神經(jīng)元皮層脊髓束的主要功能是控制肢體遠端肌肉的活動，特別是手指的活動通過腦干神經(jīng)元間接地控制脊髓運動神經(jīng)元。在初級運動皮層、前運動皮層和輔助運動區(qū)，均有神經(jīng)元投射至腦干的網(wǎng)狀脊髓神經(jīng)元及其他下行神經(jīng)元而間接影響脊髓運動神經(jīng)元皮層脊髓神經(jīng)元經(jīng)過上頸段脊髓中的脊髓固有神經(jīng)元，再影響位于頸膨大中的支配前臂肌肉的運動神經(jīng)元經(jīng)過抑制性中間神經(jīng)元以施加抑制性影響當前71頁，總共112頁。71次級運動區(qū)的運動功能初級運動皮層主要和運動的執(zhí)行有關(guān)次級運動區(qū)主要與運動的準備（策劃）有關(guān)使用PET影像研究局部腦血流與運動的關(guān)系：執(zhí)行簡單動作如單指按壓彈簧，則4區(qū)(S1)的手代表區(qū)血流增加；執(zhí)行復雜動作如輪排手指，則輔助運動區(qū)(S2)的血流亦增加；若只默想復雜動作，則僅有輔助運動區(qū)的血流增加當前72頁，總共112頁。72次級運動區(qū)的運動功能次級運動區(qū)是選擇正確的運動戰(zhàn)略所必需和初級運動皮層相比，損毀次級運動區(qū)(前運動皮層、輔助運動區(qū)和后頂葉皮層區(qū))引起更為復雜的運動異常，主要影響制定正確運動策略的能力一側(cè)的輔助運動區(qū)和前運動皮層被損毀后，猴不會使用對側(cè)前臂繞過擋在前面的透明塑料板，并通過側(cè)面的洞去取所看見的食物，相反，猴總是試圖直接去取食物而一再撞到塑料板上這種運動缺損和人的前額葉聯(lián)絡(luò)皮層或后頂葉皮層受損時引起的失用癥(apraxia)相似。這種病人能正常進行簡單的運動，但喪失了做需要有次序地收縮肌肉的較復雜的動作的能力，例如刷牙和梳頭等當前73頁，總共112頁。73Thebasalgangliacontrolofmovement當前74頁，總共112頁。74基底神經(jīng)節(jié)(basalganglia)是從端腦衍生的一些皮層下神經(jīng)核團的總稱，位于大腦兩半球的深部。基底神經(jīng)節(jié)中與運動功能有關(guān)的主要是紋狀體(striatum)尾核與殼核是基底神經(jīng)節(jié)的主要輸入核(inputnuclei)，蒼白球的內(nèi)側(cè)部、腳內(nèi)核和黑質(zhì)網(wǎng)狀部是基底神經(jīng)節(jié)的主要輸出核(outputnuclei)，后兩者的結(jié)構(gòu)和機能也很相似當前75頁，總共112頁。75Asummaryoftheloopfromthecortextothebasalganlgliatothethalamusandbacktoarea6Cerebralcortex(SMA)CaudatenucleusPutamenNewStriatumGlobuspallidus(OldStriadum)StriadumThalamus(theventrallateralnucleus,VLo)Frontalcortexneuron(Input)(Output)紋狀體的主要傳入沖動來自大腦皮層廣泛的區(qū)域(運動區(qū)、體感區(qū)、聯(lián)合區(qū)、邊緣區(qū)甚至頂葉)傳出沖動經(jīng)過丘腦返回皮層，主要是輔助運動區(qū)(supplementarymotorarea)和運動前皮層(premotorcortex)，而與脊髓沒有直接的聯(lián)系當前76頁，總共112頁。76基底神經(jīng)節(jié)與大腦皮層的纖維聯(lián)系，與運動有關(guān)的主要為三條回路皮層新紋狀體(尾、殼核)蒼白球(內(nèi)側(cè)部)丘腦皮層皮層新紋狀體(尾、殼核)蒼白球(外)丘腦底核蒼白球(內(nèi))丘腦皮層皮層新紋狀體(尾、殼核)黑質(zhì)丘腦皮層基底神經(jīng)節(jié)與與大腦皮層之間主要的回路聯(lián)系當前77頁，總共112頁。771.皮層新紋狀體蒼白球(內(nèi)側(cè))丘腦皮層回路大腦皮層(包括運動區(qū)、體感區(qū)、聯(lián)合區(qū)、邊緣區(qū)甚至頂葉)

新紋狀體(包括尾核和殼核，即紋狀體的輸入核)

蒼白球的內(nèi)側(cè)部

丘腦(包括腹前核、腹外側(cè)核、內(nèi)側(cè)背核和中央中核)

大腦皮層(主要是運動區(qū)和輔助運動區(qū)皮層)當前78頁，總共112頁。782.皮層新紋狀體蒼白球(外)丘腦底核蒼白球(內(nèi))丘腦皮層回路大腦皮層相當廣泛的區(qū)域

新紋狀體

蒼白球的外側(cè)部

丘腦底核蒼白球的內(nèi)側(cè)部

丘腦

皮層運動區(qū)和運動前區(qū)當前79頁，總共112頁。793.皮層新紋狀體黑質(zhì)丘腦皮層回路大腦皮層相當廣泛的區(qū)域(包括運動區(qū)、體感區(qū)、聯(lián)合區(qū)、邊緣區(qū)甚至頂葉)

新紋狀體

黑質(zhì)網(wǎng)狀部

丘腦的腹前核和腹外側(cè)核

大腦皮層(運動區(qū)和輔助運動區(qū))紋狀體(尾殼核)黑質(zhì)間存在具有局部定位特征的往返纖維聯(lián)系從黑質(zhì)的致密部有纖維投向新紋狀體，它組成多巴胺能神經(jīng)元系統(tǒng)；但黑質(zhì)除有纖維至上丘和腳橋被蓋核外，沒有其他向下投射的纖維 所以，基底神經(jīng)節(jié)的運動功能是通過大腦皮層中與運動控制有關(guān)的區(qū)域而間接實現(xiàn)的當前80頁，總共112頁。80直接通路易化運動直接通路包括通路1和3從皮層到新紋狀體(輸入核)的遞質(zhì)是谷氨酸，是興奮性的；從新紋狀體到蒼白球內(nèi)側(cè)部及黑質(zhì)網(wǎng)狀部(輸出核)的遞質(zhì)是GABA和P物質(zhì)，是抑制性的；從這些輸出核到丘腦的遞質(zhì)也是GABA，也是抑制性的；再由丘腦返回到皮層的輔助運動區(qū)，則是興奮性的。當皮層有興奮沖動下行到紋狀體的輸入核使它興奮時，就會使輸出核中的抑制細胞抑制，從而激活(去抑制)了丘腦的神經(jīng)元，再通過輔助運動區(qū)和運動前區(qū)激活運動皮層和向腦干及脊髓的投射神經(jīng)元，從而起易化運動的效果當前81頁，總共112頁。81間接通路抑制運動間接通路包括通路2從皮層到新紋狀體(輸入核)的遞質(zhì)是谷氨酸，是興奮性的；從紋狀體輸入核到蒼白球外側(cè)部的遞質(zhì)是GABA和腦啡肽，是抑制性的；從蒼白球外側(cè)部到丘腦底核的遞質(zhì)是GABA，也是抑制性的；從丘腦底核到蒼白球內(nèi)側(cè)部(輸出核)的遞質(zhì)是谷氨酸，是興奮性的；從蒼白球內(nèi)側(cè)部到丘腦的遞質(zhì)是GABA，抑制性的；再由丘腦返回到皮層的輔助運動區(qū)，則是興奮性的當皮層與紋狀體輸入核興奮而使蒼白球外側(cè)部抑制時，轉(zhuǎn)而使丘腦底核產(chǎn)生興奮(去抑制)，也就興奮了紋狀體的輸出核，抑制了丘腦，從而降低了輔助運動區(qū)的興奮性，產(chǎn)生抑制運動的效果當前82頁，總共112頁。82黑質(zhì)－紋狀體多巴胺能投射易化運動從黑質(zhì)中的多巴胺能神經(jīng)元發(fā)出纖維到新紋狀體，易化運動興奮直接通路而易化運動，也就是使新紋狀體通過GABA與P物質(zhì)等抑制紋狀體的輸出核，興奮丘腦，最后起易化運動的作用。抑制間接通路而易化運動，就是使新紋狀體抑制，致使GABA與腦啡肽的抑制作用降低，因而興奮了蒼白球的外側(cè)部，抑制丘腦底核，從而抑制紋狀體輸出核，興奮了丘腦，最后也起易化運動的作用。所以，多巴胺能投射通過直接通路或間接通路，最后對運動都起易化作用當前83頁，總共112頁。83+-Parkinson’sdiseaseHuntington’sdisease-當前84頁，總共112頁。84Thecerebellum

controlofmovement當前85頁，總共112頁。85Overview小腦(cerebellum)是中樞神經(jīng)系統(tǒng)中最大的運動結(jié)構(gòu)主要作用是維持軀體平衡、調(diào)節(jié)肌肉張力和協(xié)調(diào)隨意運動小腦并不直接發(fā)起運動和指揮肌肉的活動，而是作為一個皮層下的運動調(diào)節(jié)中樞配合皮層完成這些運動機能切除全部小腦并不妨礙運動的發(fā)起和執(zhí)行，但運動是以緩慢、笨拙和不協(xié)調(diào)的方式進行的另