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Chapter 11 - Movement
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- 1Sensory feedbackProprioception - info about body movement & position - guides/refines/coordinates movements
Muscle Receptors - muscle spindle (stretch) & Golgi tendon organ (tension) - 2Stretch reflexDisturbance -> muscle stretched -> activates muscle spindle fibers -> excites motoneurons in agonist & activates interneurons to inhibit antagonist
- 3Functions of spinal cordConvey info between brain & periphery
Can regulate movements unconsciously - reflexes, simple (ext/withdrawal) or complex (walking, scratching) - 4Motor neuronsIn Ventral horn of spinal cord
Project to muscles
Topographically arranged - 5Corticospinal tractPath between motor cortex & brain stem/spinal cord
Ventral CST activates most medial calls, lateral CST activates rest
Spinal tracts contact both motor & interneurons
Most axons in tract originate in pyramidal cells in layer V of M1 (some from premotor & sensory)
Decends into brainstem
Most cross to contralateral = lateral CST
Some stay ipsilateral = ventral CST - 6Researchers in motor cortex organizationFritisch & Hitzig - stimulated dog's brain -> movements on contralateral side
Penfield - mapped brain areas (detailed) including M1, topographically arranged - 7What activates motor cortex cells?When a certain muscle is activated
When a limb moves a certain direction (regardless of what muscles are used) - 8Old understanding of executive control of movementMove -> feedback -> analyze -> adjust -> repeat
- 9Lashley's understanding of executive movement controlSpeed limits in CNS too slow for constant feedback
Complex behaviours are broken into motor sequences - 10Closed vs. open loop controlClosed: uses feedback, maximizes accuracy, usually for slow/smooth sustained movements
Open: too fast for feedback, anticipate error through experience/learning, ballistic movements - 11Frontal lobesPlanning & initiation of movements
Plans, coordinates & executes precise movements
4 main areas: Prefrontal cortex, Supplementary motor cortex, Premotor cortex, Primary motor cortex - 12Prefrontal cortexPlans complex behaviours (not simple movements)
IDs goals for behaviours
Regulates premotor area - 13Supplementary motor areaFor movement initiation
Planning of movement based on memory (implicit, rehearsal)
Receives input from basal ganglia to modulate M1 activity
Lesions -> impairment of movement initiation - 14Premotor areaProduces complex movement sequences - not for details of particular movement
Selects right motor program
Coordinates simultaneous movements
Regulates primary motor cortex
Lesions -> can't coordinate seperate movements - 15Primary motor cortexFor executing skilled movements with fine detail & for complex movements
Larger areas for parts with fine/complex movements - representations can change with training
Damage -> partial paralysis (opposite side) - 16Pincher vs. power graspPincher - requires skill, coordination of digits & dexterity -> can't do with primary motor cortex damage
Power - strong but unskilled & doesn't require dexterity -> persists with primary motor cortex damage - 17Basal gangliaParts: caudate, putamen, global pallidus, substantia nigra
1) Amplitude/force & direction of movement, 2) modulates activity from other cortical regions, 3) guides memory-influenced behaviours
Input from & projects back to: all cortex, limbic system, substantia nigra through thalamus
Contains topographic representation - 18CerebellumFor movement skill - acquiring & maintaining motor skills
Role in timing & coordination - rapid skilled movements & learned motor responses
Regions specialized for different functions
Purkinje cells - only inhibitory - 19Huntington'sDamage to caudate putamen (in basal g)
-> involuntary exaggerated movements
Clumsiness & twitches -> intense jerks
Can also have behavioural changes
Genetic - trinucleotide repeat (number ~ severity & onset)
Hyperkinetic - 20Parkinson'sLoss of dopaminergic cells in substantia nigra (in basal ganglia) -> decreased input to caudate & putamen -> inability to produce normal movements - difficulty initiating
Tremors, rigidity, less voluntary motion
Treatment: L-DOPA, transplants, DBS
Hypokinetic
Can be hereditary - α-synuclein or parkin - 21Regions of cerebellumFlocculus - balance & eye movements
Medial - face & midline; damage -> deficits in balance, eye movements, posture & walking
Lateral - regulates cortical areas for movement of limbs, hands, feet & digits; damage -> decomposition of movements - 22Muscular dystrophyMuscle wasting
Duchenne's - x-linked, early onset
No dystrophin gene - 23Myasthenia gravisAutoimmune - attacks AChRs
Causes muscle weakness - head & face first, then speech & breathing
Treat with immune suppressors - 24Amyloid lateral sclerosis (ALS)Lou Gehrig's disease
Destroys motoneurons in spinal cord & brainstem
Muscles waste away without input
Unknown cause - sometimes aging, toxins, hereditary (10%) , virus, autoimmune, endocrine - 25Spinal damageSevered -> flaccid paralysis - loss of reflexes below transection
Hemisection -> damage on contralateral or ipsilateral side depending on where nerves for that function cross
CNS can't regrow nerves
Treatment: stem cells, glial bridge, neurotrophins, peripheral nerve bridge - 26Views on motor controlBehavioural - basic units of behaviour are reflexes; movement determined by motor plans; limits for complex behaviour
Control Systems - 2 goals: accuracy & speed; closed-loop = feedback for accuracy vs. open-loop = no feedback for speed
NS - hierarchically organized motor control systems - 27Muscle spindlePrimary sensory ending (annulospiral) - middle of fiber, early max discharge then slow - for dynamic length/change
Secondary endings (flower spray) - ends of fiber, slow to stretch - for static length
Gamma MNs - change tension of spindle to control sensitivity
Alpha MNs - fast, control extrafusal muscle fibers - 28Golgi Tendon OrganMonitor force of contractions
Stimulation -> inhibition of active muscle - 29Central pattern generatorNeural circuitry for generating rhythmic patter of behaviour (ex walking)
Spinal cord level - 30Nonprimary motor cortexAnterior to primary
Aids complex behaviours
Supplementary motor area + premotor cortex - 31Extrapyramidal systemIncludes brainstem structures
Reticulospinal tract - originates in reticular formation (brainstem)
Rubrospinal tract - originates in red nucleus (midbrain)
Both synapse spinal interneurons
Most important structures = basal ganglia & cerebellum - 32Divisions of cerebellumSpinocerebellum - muscle tone & coordination - upper
Cerebrocerebellum - motor planning, learning & memory - lower
Vestibulocerebellum - balance, posture, eye movement coordination - 33Strokes & cortex injuriesPlegia - paralysis or Paresis - partial paralysis/weakness
Usually contralateral
Spasticity - increased rigidity (exaggerated stretch reflex) - 34ApraxiaImpairment of ability to start & execute skilled movement without paralysis
Damage in non-motor parts
Ideomotor - can't do simple action in response to verbal command but can spontaneously
Ideational - can't do sequence but can do individual steps - 35Cerebellum damageAtaxia - spinocerebellum damage - impairs direction, extent & rate of movement
Decomposition of movement - cerebrocerebellum damage - gestures broken up into segments, not smooth
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- Fichas sobre Chapter 11 - Movement, creado por Megan Willerth el 30/10/2014.
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- Megan Willerth
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