* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 10 Control of Movement
Cognitive neuroscience of music wikipedia , lookup
Neuroscience in space wikipedia , lookup
Sensory substitution wikipedia , lookup
Neuroanatomy wikipedia , lookup
Development of the nervous system wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Nervous system network models wikipedia , lookup
Molecular neuroscience wikipedia , lookup
End-plate potential wikipedia , lookup
Electromyography wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Embodied language processing wikipedia , lookup
Evoked potential wikipedia , lookup
Synaptic gating wikipedia , lookup
Microneurography wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Synaptogenesis wikipedia , lookup
Proprioception wikipedia , lookup
Muscle memory wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Central pattern generator wikipedia , lookup
Physiology Unit2 CONTROLOFMOVEMENT InPhysiologyToday MotorProgram • Patternofneuralactivityrequiredtoproperlyperformthedesired movement • Highestlevel – Motorcortex – Decidewhatmovementwilloccur • Middlelevel – Cerebellum,basalganglia,thalamus,brainstem,spinalcord, – Posturesandmovementsneededtocarryouttheaction – Receivessensoryinputfromlocallevel • Locallevel – Brainstem,Spinalcord – Afferentneurons,Motorneurons,Interneurons – Monitorsmusclelengthandtensionconstantlyadjustingmuscle contraction ControlofBodyMovement Motor Control Hierarchy LocalControlofMotorNeurons • Localcontrollevelsarerelaypointsfor instructionscomingfromhigherlevelsinthe motorprogram • Adjustingmotorunitactivitytolocalconditions (obstaclestomovement,pain) • Localcontrolsystemsusesensoryinformation fromsensoryreceptors – – – – Muscles Tendons Joints Overlyingskin SomaticNervousSystem Interneurons • • • Mostofthesynapticinputfrom descendingpathwaystomotor neuronsarefrominterneurons 90%ofspinalcordneurons Integrateinputs – Highercenters – Peripheralreceptors – Otherinterneurons • Determinewhichmusclesare activatedandwhen – Coordinatesrepetitive,rhythmic activities • Walking,running • Canturnmovementsonoroff – Grabbingahotplate ReflexArc • Thebasicanatomical/functionalunitofthe nervoussystem • Components: 1. 2. 3. 4. 5. Sensoryreceptor 1st ordersensoryneuron Integratingcenter(brain/spinalcord) Motorneuron Effectororgan(skeletalmuscle,cardiacmuscle,smooth muscle,glands) ReflexArcComponents 1. Sensoryreceptor Constantlysamplesitsenvironment – • • Phasicreceptors Tonicreceptors 2. 1st ordersensoryneuron Afferent,peripheral;leadingtotheCNS – 3. Integrating/coordinatingcenter Centralnervoussystem – • • • Processesallincomingsensoryinformation Integratessensoryinformation Coordinatesmotorcommands ReflexArcComponents 4. Motorneuron – Efferent,peripheral;leadingfromtheCNS • Somaticmotorneuron • Autonomicmotorneuron • Sympatheticdivision • Parasympatheticdivision 5. Effectororgan – – – Amuscleoraglandthatresponds Skeletalmuscle(somatic) Smoothmuscle,cardiacmuscle,glands(autonomic) TheSpinalCord:ReflexArc • Controlsreflexactivity LocalAfferentInput • Afferentfibersbringinformationfromsensory receptorsfrom – Skeletalmuscles(primemovers) – Nearbymuscles(synergists,antagonists,fixators) – Tendons,jointsandskinaffectedbythemovement • Sensoryreceptorsforlocalskeletalmuscle controlmonitor – Lengthandtension – Jointmovement AscendingTracts LengthMonitoringSystem • Musclespindlestretch receptors – Stretchreceptorsembedded inmuscle • Monitormusclelength • Themoreorthefasterthe muscleisstretched the greatertherateofreceptor firing • Contraction ofthe extrafusalfibersshortens themuscleandslowsdown therateoffiring Alpha-GammaCo-Activation • Preventslossofsensory informationwhenthe muscleiscontracting • Alphamotorneurons – Extrafusal fibers • Gammamotorneurons – Gammamotorneurons stimulatethetwoendsof theintrafusal fibersto contract – Maintainstensioninthe spindleapparatus TensionMonitoringSystems • Tensiondependson – Musclelength – Loadonmuscle – Degreeofmusclefatigue • Sensoryinformationon tension – Vision – Somatosensoryinput – Golgitendonorgans • Inhibitorysynapses preventexcessive contractionorpassive stretching MonosynapticReflex – Reflexresponsethat involvesONLY one synapse – Sensoryneuronfromthe extensormuscle synapseswiththemotor neuronforthatextensor muscle – Onlyfoundinthestretch reflex PolysynapticReflex • Reflexresponsethat involvesMORETHANone synapse – Interneurons • Ipsilateral’sflexormuscle’s motorneuronstimulated – Withdrawalreflex • Oppsositelimb (contralateral)extendedto supportthebodiesweight – Crossedextensorreflex ControlbytheCerebralCortex • Planningandcontrolling ongoingmovement • Motorcortex,premotor area – Givesrisetomostnerve fiberstodescending pathwaysformotorcontrol • Corticalneuronsforma neuralnetwork – Manyneuronsparticipatein eachsinglemovement – Coordinationofmanypartsto produceasmooth, purposefulmovement SubcorticalandBrainstemNuclei • Planningandmonitoringmovement • Establishtheprogramthatdeterminesthe specificsequenceofmovementsneededto accomplishadesiredaction • Basalganglia – Subcorticalnuclei – Linkcircuits • Somefacilitatemovements • Somesuppressmovements Cerebellum 1. Influencesbalanceandposture – Inputtobrainstemnuclei 2. Providestimingsignalstothecortexandspinal cord – Forpreciseexecutionofdifferentphasesofthemotor program – Agonist/antagonisttiming 3. Coordinatesmovementinvolvingmultiplejoints 4. Storesmemoriesofmovements - Easiertoaccomplishthenexttime TypesofDescendingPathways • PyramidalTract(corticospinalpathway) – Planningtracts – Frommotorcortex – Excitatory • ExtrapyramidalTract(brainstempathway) – Coordinatingtracts • Excitatory/Inhibitory – Frombrainstem – Coordinatethe“plan” fromthemotorcortex – Maintainpostureduringmovement DescendingPathways CorticospinalPathway • Pyramidaltract • Nervesfrommotorcortex terminateinthespinal cord • Decussation ofthe pyramidsinmedulla • Convergence/divergence • Controlmusculature involvedinfineisolated movements – Hands,fingers DescendingPathways BrainstemPathway • Extrapyramidaltract • Nervesinthebrainstem terminateinthespinal cord • Mostlyipsilateral • Controllargemuscle groups – Posture – Locomotion – Head,bodymovements turningtowardsa stimulus MuscleTone • MuscleTone – Resistancetostretch – Tension – Elasticpropertiesofmuscle,tendons • Slightlycontractedstateofmusclesevenatrest • Maintainedbystretchreflexes • Function – Helpsstabilizejoints – Improvesposture – Createsoptimallengthformusclecontraction • Requiresconstantsensoryfeedbacktocontrolmuscle activity