北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座

CentralNervousSystemControlofMovementXING,GUOGANG(邢國(guó)剛),MD.Ph.D.北京大學(xué)神經(jīng)科學(xué)研究所NeuroscienceResearchInstitute,PekingUniversityEmailaddress:ggxing@1北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第1頁(yè)Introduction生命在于運(yùn)動(dòng)……運(yùn)動(dòng)是動(dòng)物維系個(gè)體生存和種族繁衍基本功效之一2北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第2頁(yè)Howdoesacoordinatedmovementachieved?3北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第3頁(yè)Thementalbodyimageseemstobegeneratedbysomatosensory,proprioceptive,andvisualinputstotheposteriorparietalcortex(area5,area7)Abaseballpitcherplanningapitch…4北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第4頁(yè)Thehighestlevel－

strategyRepresentedbytheassociationareasofneocortexandbasalgangliaoftheforebrainIsconcernedwithstrategy:ThegoalofthemovementandthemovementstrategythatbestachievesthegoalThemotorcontrolhierarchyhavethreelevels5北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第5頁(yè)Themiddlelevel－tacticsRepresentedbythemotorcortexandcerebellumIsconcernedwithtacticsThesequencesofmusclecontractionsArrangedinspaceandtimeRequiredtosmoothlyandaccuratelyachievethestrategicgoalThemotorcontrolhierarchyhavethreelevels6北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第6頁(yè)Thelowestlevel－

execution

RepresentedbythebrainstemandspinalcordIsconcernedwithexecutionActionofthemotorneuronandinterneuronpoolsthatgeneratethegoal-directedmovementandmakeanynecessaryadjustmentsofpostureThemotorcontrolhierarchyhavethreelevels7北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第7頁(yè)Overview脊髓內(nèi)“下運(yùn)動(dòng)神經(jīng)元(Lowerneurons)”，除了受到脊髓內(nèi)局部環(huán)路影響外，還受到大腦皮層運(yùn)動(dòng)區(qū)及腦干中許多“上運(yùn)動(dòng)神經(jīng)元(Upperneurons)”支配和協(xié)調(diào)基底神經(jīng)節(jié)和小腦則向那些上運(yùn)動(dòng)神經(jīng)元提供某種感覺(jué)、認(rèn)知或感性信息，使運(yùn)動(dòng)愈加準(zhǔn)確和協(xié)調(diào)8北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第8頁(yè)9北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第9頁(yè)SensorimotorcortexBasalgangliaCerebellumBrainstemSpinalcordInterneuron-MotorneuronMotorunit(finalcommonpathway)Receptorsmuscle,skin,joint12345Theseprogramsareaccessed,executed,andmodifiedbydescendingcommandsfromthebrainThebrain’scommandandcontrolofthemotorprogramsinthespinalcordThemotorsystemconsistsofallourmusclesandtheneuronsthatcommandthemThespinalcordcontainscertainmotorprogramsforthegenerationofcoordinatedmovementsThemotorcontrolcanbedividedintotwoparts:Thespinalcord’scommandandcontrolofcoordinatedmusclecontraction10北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第10頁(yè)P(yáng)art1

SpinalControlofMovement11北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第11頁(yè)Introduction“runningaroundlikeachickenwithitsheadcutoff”

Therhythmicmovementscouldbeelicitedinthehindlegsofcatsanddogslongaftertheirspinalcordshadbeenseveredfromtherestofthecentralnervoussystem–CharlesSherington&GrahamBrown(English)Theimportanceofcircuitrywithinthespinalcordforthecoordinatedcontrolofmovements12北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第12頁(yè)Spinalcircuitry

controlofmovement13北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第13頁(yè)Spinalmotorneurons

Alphamotorneurons

Innervateskeletalmuscle(extrafusalmuscle)

Function:directlycommandmusclecontractGammamotorneurons

Innervatemusclespindle(intrafusalmuscle)

Function:regulatingthemusclespindleInterneurons

AllowscoordinatedmotorprogramstobegeneratedFinalcommonpathway(directlycommandmusclecontract)Compare:

UppermotorneuronsLowermotorneurons14北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第14頁(yè)TheLowerMotorNeurons

－AlphamotorneuronsAlphamotorneuronsaredirectlyresponsibleforthegenerationofforcebymuscleMotorunit:onealphamotor

neuronandallofthemusclefibersitinnervatescollectivelymakeupmotorunit,theelementarycomponentofmotorcontrolMotorneuronpool:Thecollectionofalphamotorneuronsthatinnervatesasinglemuscle15北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第15頁(yè)ThemotorunitisanalphamotorneuronandallofthemuscleAmotorunitandmotorneuronpoolThemotorneuronpoolisallofthealphamotorneuronsthatinnervateonemuscle16北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第16頁(yè)Muscleinnervationbylowermotorneurons30mixedspinalnervescervical1-8thoracic1-12lumbar1-5sacral1-5TheventralhornofthespinalcordcontainsmotorneuronsthatinnervateskeletalmusclefibersVentralroots+Dorsalroot=Spinalnerve17北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第17頁(yè)Thecervicalenlargementofthespinalcordcontainsthemotorneuronsthatinnervatethearmmuscles

Thelumbarenlargementcontainsneuronsthatinnervatethemusclesoftheleg

支配上肢神經(jīng)元集群位于頸膨大處，支配下肢則在腰膨大處ThedistributionofmotorneuronsinthespinalcordThemotorneuronsthatinnervatedistalandproximalmusculaturearefoundmainlyinthecervicalandlumbar-sacralsegmentsofthespinalcordWhereasthoseinnervatingaxialmusculaturearefoundatalllevelsSegmentsC3-T1haveaswollenventralhornthatinnervateskeletalmusculatureinarmsSegmentsL1-S3haveaswollenventralhornthatinnervateskeletalmusculatureinlegs18北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第18頁(yè)Motorneuronscontrollingflexorsliedorsaltothosecontrollingextensors

Motorneuronscontrollingaxialmusclesliemedialtothosecontrollingdistalmuscles支配軀干部肌肉神經(jīng)元位于脊髓前角灰質(zhì)最內(nèi)側(cè)，由此向外排列神經(jīng)元?jiǎng)t支配肢體由近及遠(yuǎn)分布肌肉Thedistributionoflowermotorneuronsintheventralhorn19北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第19頁(yè)Muscleweaknessandparalysis－所支配骨骼肌癱瘓、肌張力下降、腱反射消失(軟癱)肌萎縮、纖維顫動(dòng)或肌束顫動(dòng)見(jiàn)于如肌萎縮側(cè)索硬化癥(amyotrophiclateralsclerosis,

ALS)：Selectivedamagetoalphamotorneurons(degeneration)－脊髓-運(yùn)動(dòng)神經(jīng)元進(jìn)行性潰變?yōu)橹飨逻\(yùn)動(dòng)神經(jīng)元損傷表現(xiàn)20北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第20頁(yè)LouGehrigFarewellSpeech:"Fans,forthepasttwoweeksyouhavebeenreadingaboutthebadbreakIgot.YettodayIconsidermyselftheluckiestmanonthefaceofthisearth.……SoIcloseinsayingthatImayhavehadatoughbreak,butIhaveanawfullottolivefor."LouGehring,astarbaseballplayerwithNewYorkYankees,whodiedofALS(amyotrophiclateralsclerosis)in193621北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第21頁(yè)InputstoalphamotorneuronsThisinputisimportantfortheinitiationandcontrolofvoluntarymovementThisinputmaybeexcitatoryorinhibitoryandispartofthecircuitrythatgeneratesthespinalmotorprogramsThisinputprovidesfeedbackaboutmusclelength22北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第22頁(yè)SPINALCONTROLOFMOTORUNITSHowtheactivityofthemotorneuronisitselfcontrolled?23北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第23頁(yè)ReflexReceptorEffectorSpinalMotorNeuron(center)SkinMuscleJointMusclecontractionHigherCenterVoluntarymovementsNociceptivestimulusStretchmusclesPosturemaintenance24北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第24頁(yè)Themyotaticreflex(stretchreflex)Twotypesofmyotaticreflex

－TendonreflexandmuscletonusA.Tendonreflex

—快速牽拉肌腱而發(fā)生牽張反射Clinicapplication：了解脊髓不一樣節(jié)段功效狀態(tài)

reflexmothedCentralsiteeffect肘反射扣擊肱二頭肌肌腱頸5-7肘部屈曲膝反射扣擊股四頭肌肌腱腰2-4小腿伸直跟腱反射扣擊跟腱腰5-骶2腳向足底方向屈曲單突觸反射潛伏期很短，約0.7s只夠一次突觸傳遞時(shí)間延擱25北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第25頁(yè)+26北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第26頁(yè)B.Muscletonus

肌肉受到遲緩而連續(xù)牽拉而發(fā)生收縮－使骨骼肌能保持一定肌肉張力意義:維持身體姿勢(shì)(posture)，而不表現(xiàn)顯著動(dòng)作表現(xiàn)：extensor(伸肌)和flexor(屈肌)都發(fā)生肌擔(dān)心直立時(shí)，以伸肌擔(dān)心為主，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，引發(fā)肌擔(dān)心反射，肌擔(dān)心度增加以反抗關(guān)節(jié)屈曲因重力連續(xù)作用于關(guān)節(jié)，肌擔(dān)心也就連續(xù)發(fā)生。使直立姿勢(shì)得以維持多突觸反射潛伏期較長(zhǎng)，經(jīng)過(guò)多個(gè)突觸傳遞27北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第27頁(yè)

Musclespindles:ConsistsofspecializedskeletalmusclefibersInthismiddleregion,groupIa

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

是一個(gè)可感受肌肉長(zhǎng)度改變或感受牽拉刺激本體感受器梭內(nèi)肌感受部裝置位于中間,收縮成份位于兩端,梭內(nèi)肌收縮時(shí)或牽拉梭外肌時(shí),感受裝置對(duì)牽拉敏感性增高

28北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第28頁(yè)+29北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第29頁(yè)GammamotorneuronsExtrafusalfibersareinnervatedbyalphamotorneuronsIntrafusalfibersreceivetheirmotorinnervationbyanothertypeoflowermotorneuroncalledagammamotorneuronGammamotorneuronsinnervatetheintrafusalmusclefiberatthetwoendsofthemusclespindleActivationofthesefiberscausesacontractionofthetwopolesofthemusclespindle,therebypullingonthenon-contractileequatorialregionandkeepingtheIaafferentsactive30北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第30頁(yè)ThefunctionofgammamotorneuronsActivationofalphamotorneuronsshortenstheextrafusalmusclefibers.Ifthemusclespindlebecomesslack,itgoes“offtheair”andnolongerreportsthelengthofthemuscleActivationofgammamotorneuronscontractsthepolesofthespindle,keepingit“ontheair”31北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第31頁(yè)TheGammaloopChangingtheactivityofthegammamotorneuronschangesthesetpointofthemyotaticfeedbackloopTheGammaloopGammamotorneuronintrafusalmusclefiberIaafferentalphamotorneuronextrafusalmusclefibersAlphaandgammamotorneuronsaresimultaneouslyactivatedbydescendingcommandsfromthebrain32北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第32頁(yè)P(yáng)roprioceptionfromGolgitendonorgansGolgitendonorganActslikeastraingauge,itmonitorsmuscletension,ortheforceofcontractionLocatedatthejunctionofthemuscleandthetendonandareinnervatedbygroupIbsensoryaxonsthatareslightlysmallerthantheIaaxonsinnervatingthemusclespindles33北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第33頁(yè)GolgitendonorgansrespondtoincreasedtensiononthemuscleandtransmitthisinformationtothespinalcordviatypeIbsensoryafferents.Becausetheactivatedmuscledoesnotchangelength,theIaafferentsremainsilentinthisexample當(dāng)肌肉等長(zhǎng)收縮時(shí),腱器官傳入沖動(dòng)頻率,肌梭傳入沖動(dòng)頻率不變;當(dāng)肌肉等張收縮時(shí),腱器官傳入沖動(dòng)頻率不變,肌梭傳入沖動(dòng)頻率Golgitendon

organslieinseriesbetweenthemusclefibersandtheirpointsofattachmentMusclespindlesarearrangedparalleltotheextrafusalfibers34北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第34頁(yè)TheIbafferentsenterthespinalcord,branchrepeatedly,andsynapseoninterneuronsintheventralhornSomeoftheseinterneuronsforminhibitoryconnectionswiththealphamotorneuronsinnervatingthesamemuscle.ThisisthebasisforthereversemyotaticreflexCircuitryofthereversemyotaticreflex＋-Musclespindlesituatedinparallelwiththemusclefibers,GolgitendonorgansaresituatedinseriesIaactivityfromthespindleencodesmusclelengthinformationWhileIbactivityfromtheGolgitendonorganencodesmuscletensioninformation腱器官是張力感受器,其傳入沖動(dòng)對(duì)同一肌肉運(yùn)動(dòng)神經(jīng)元起抑制作用肌梭是長(zhǎng)度感受器,其傳入沖動(dòng)對(duì)同一肌肉運(yùn)動(dòng)神經(jīng)元起興奮作用當(dāng)肌肉被動(dòng)牽拉時(shí),二者傳入沖動(dòng)頻率均：首先興奮肌梭發(fā)動(dòng)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特點(diǎn)：反射弧簡(jiǎn)單，感受器和效應(yīng)器在同一塊肌肉35北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第35頁(yè)SignificanceofthereversemyotaticreflexInextremecircumstances,thisreflexarcprotectsthemusclefromoverloadThenormalfunctionistoregulatemuscletensionwithinanoptimalrangeAsmuscletension

increases,theinhibitionofthealphamotorneuronslowsmusclecontractionAsmuscletensionfalls,theinhibitionofthealphamotorneuronisreduced,andmusclecontractionincreasesThistypeofproprioceptivefeedbackisthoughttobeparticularlyimportantfortheproperexecutionoffinemotoracts,suchasthemanipulationoffragileobjectswiththehands,whichrequireasteadybutnottoopowerfulgrip36北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第36頁(yè)SpinalinterneuronsMostoftheinputtothealphamotorneuronscomesfrominterneuronsofthespinalcordInterneuronsreceivesynapticinputfromprimarysensoryaxons,descendingaxonsfromthebrain,andcollateralsoflowermotorneuronaxonsTheinterneuronsarethemselvesnetworkedtogetherinawaythatallowscoordinatedmotorprogramstobegeneratedinresponsetotheirmanyinputs37北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第37頁(yè)Reciprocalinhibitionofflexorsandextensorsofthesamejoint+++-InhibitoryinputContractionofonesetofmusclesaccompaniedbytherelaxationoftheantagonistmusclesiscalled

reciprocalinhibitionReciprocalinhibitionisalsousedbydescendingpathwaystoovercomethepowerfulmyotaticreflex38北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第38頁(yè)(A

&Cfibers)ExcitatoryinputFlexorreflex:usedtowithdrawalimbfromanaversivestimulus,suchasthewithdrawalofyourfootfromthethumbtackThepainfibersenteringthespinalcordbranchprofusedlyandactivateinterneuronsinseveralspinalsegments.Thesecellseventuallyexcite

thealphamotorneuronsthatcontrolalloftheflexormusclesoftheaffectedlimb(andinhibitoryinterneuronsarealsorecruitedtoinhibitthealphasthatcontroltheextensors)++++Circuitryofthepolysynapticflexorreflex39北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第39頁(yè)Circuitryofthecrossed-extensorreflexSpinalcordIpsilateralextensorsinhibitedContralateralextensorsactivated(contract)Ipsilateralflexorsactivated(contract)ContralateralflexorsinhibitedIpsilateralkneejointclosesuptoremovefootfromtackContralateralkneejointopensuptosupportgreaterweight40北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第40頁(yè)ThegenerationofspinalmotorprogramsforwalkingHeadlesschickens;behaviorAcompletetransectionofacat’sspinalcordatthemid-thoraciclevelleavesthehindlimbscapableofgeneratingcoordinatedwalkingmovementsWhenyouwalk,youalternatelywithdrawandextendyourtwolegs

Whatisthemechanismtocoordinatethetiming?Thiscouldbedescendingcommandsfromuppermotorneurons?No!Thiscontrolisexertedfromwithinthespinalcord?Yes!41北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第41頁(yè)42北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第42頁(yè)CentralpatterngeneratorswithinthespinalcordThecircuitforthecoordinatedcontrolofwalkingmustresidewithinthespinalcordIngeneral,circuitsthatgiverisetorhythmicmotoractivityarecalledcentralpatterngenerators

Howdoneuralcircuitsgeneraterhythmicpatternsofactivity?Thesimplestpatterngenerators,aresingleneuronswhosemembranepropertiesendowthemwithpacemakerproperties(pacemakerneurons)43北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第43頁(yè)Rhythmicactivityinaspinalinterneuron(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,resettingthemembraneforanotheroscillation44北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第44頁(yè)Apossiblecircuitforrhythmicalternatingactivity(walking)Walkingisinitiatedwhenasteadyinputexcitestwointerneuronsthatconnecttothemotorneuronscontrollingtheflexorsandextensors,respectively.Theinterneuronsrespondtoacontinuousinputbygeneratingburstsofoutputs.Theactivitiesofthetwointerneuronsalternatebecausetheyinhibiteachotherviaother(inhibitory)interneurons.Thus,aburstofactivityinoneinterneuronstronglyinhibitstheother(Pacemakerneuron)(Pacemakerneuron)45北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第45頁(yè)P(yáng)art2

BrainControlofMovement46北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第46頁(yè)Howdoesthebraincommunicatewiththemotorneuronsofthespinalcord?47北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第47頁(yè)Overview來(lái)自高級(jí)中樞下行投射對(duì)腦干和脊髓環(huán)路運(yùn)動(dòng)控制主要影響隨意運(yùn)動(dòng)和朝向目標(biāo)運(yùn)動(dòng)發(fā)出下行投射中樞位于腦干一些部位以及大腦皮質(zhì)運(yùn)動(dòng)區(qū)域腦干內(nèi)兩個(gè)主要結(jié)構(gòu)－前庭核和網(wǎng)狀結(jié)構(gòu)對(duì)維持姿勢(shì)很主要皮質(zhì)主要運(yùn)動(dòng)區(qū)和次要運(yùn)動(dòng)區(qū)(運(yùn)動(dòng)前區(qū))主要對(duì)運(yùn)動(dòng)進(jìn)行計(jì)劃并使運(yùn)動(dòng)高效率執(zhí)行，皮質(zhì)這種作用是經(jīng)過(guò)對(duì)腦干內(nèi)一些高級(jí)中樞以及腦干、脊髓中運(yùn)動(dòng)神經(jīng)元和環(huán)路中間神經(jīng)元控制來(lái)完成48北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第48頁(yè)Thedescendingspinaltractscontrolofmovement49北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第49頁(yè)ThedescendingspinaltractsControlpostureandunderbrainstemcontrolContolvoluntary

movementsofthedistalmusculatureandunderdirectcorticalcontrol50北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第50頁(yè)(Pyramidaltract)ControlfinemovementsofthearmsandfingersTheeffectsoflateralpathwaylesions(inmonkeys)－byDonaldLawrence&HansKuypers(inthelate1960s)TheLateralPathwaysXJoinincorticospinaltractinthelateralcolumnofthespinalcordTerminateinthedorsolateralregionoftheventralhornsandintermedialgraymatterWheremotorneuronsandinterneuronscontrolthedistalmuscles,particularlyflexorsInputfromfrontalcortexX51北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第51頁(yè)TheVentromedialPathwaysContainfourdescendingtracts

thevestibulospinaltractthetectospinaltractthepontinereticulospinaltractthemedullaryreticulospinaltract

Oringinateinthebrainstem

TerminateamongthespinalinterneuronsControllingproximalandaxialmusclesUsesensoryinformationaboutbalance,bodyposition,andthevisualenviromenttoreflexivelymaintainbalanceandbodyposture52北大神經(jīng)生物學(xué)神經(jīng)系統(tǒng)對(duì)運(yùn)動(dòng)的調(diào)節(jié)專(zhuān)家講座第52頁(yè)Thevestibulospinalandtectospinaltractskeeptheheadbalanceontheshouldersasthebodymovesthroughspace,andtheyturntheheadinresponsetonewsensorystimuli(midbrain)RecivedirectinputfromretinaReciveprojectionsfromvisualcor