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~BN21 subcortical motor control.ppt
 

~BN21 subcortical motor control.ppt

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    ~BN21 subcortical motor control.ppt ~BN21 subcortical motor control.ppt Presentation Transcript

    • Subcortical Motor Systems: Cerebellum & Basal Ganglia Lecture 21
    • Motor Loops
      • Cortex  Subcortex  Cortex  Spinal cord
      • Cerebellum
        • coordination of movement
      • Basal Ganglia
        • selection & initiation of voluntary movements ~
    • Cerebellum
      • Nonmotor functions - memory/language
      • Coordination of complex movements
      • Programs ballistic movements
        • no feedback during execution
        • direction, force, & timing
      • Motor learning
        • shift from conscious  unconscious ~
    • Cerebellum: Anatomy
      • Folia & lobules
        • analogous to sulci & gyri
      • Vermis - along midline
        • output  ventromedial pathway
      • Hemispheres
        • output  lateral pathway
      • Deep cerebellar nuclei
        • analogous to thalamus ~
    • Motor Loop Through Cerebellum
      • Lateral cerebellum
          • simplest circuit
        • 20 million axons
      • Cortex  pons & cerebellum
        • Prefrontal, Motor, PPC
      • Pons & Cerebellum  thalamus
        • VLc - ventrolateral nucleus
      • VLc  M1  lateral pathway ~
    • Pons, Cerebellum VLc Lateral Cerebellar Motor Loop Prefrontal PPC M1 M2 Distal Limbs
    • Cerebellum: Damage
      • Lesions - loss of motor coordination
      • Dysynergia
        • no simultaneous movement of joints
          • serial movement only
      • Dysmetric movements
        • to wrong coordinates
      • Alcohol intoxiction
        • depression of cerebellar circuits ~
    • Basal Ganglia
      • Caudate nucleus Putamen
      • Globus Pallidus
      • Substantia Nigra
        • Tegmentum
      • Control slow movements
        • Using immediate sensory feedback ~
      Striatum
    • Striatum Globus Pallidus Substantia Nigra Thalamus
    • Cross section of Tegmentum Substantia Nigra
    • Basal Ganglia VLo Basal Ganglia Motor Loop Prefrontal PPC M1 M2 Distal Limbs
    • Basal Ganglia Movement Disorders
    • Parkinson’s Disease
      • 1% of population
      • Nigrostriatal pathway
        • Substantia nigra neurons die
        • Progressive loss
      • Hypokinesia
        • Rigidity
        • Bradykinesia
        • Akinesia ~
    • SMA Putamen - Globus Pallidus (GP i ) - Substantia Nigra + VLo Cortex + X Parkinson’s Disease + Subthalamic Nucleus +
    • Parkinson’s Disease: Treatment
      • Basal Ganglia - Cholinergic
      • Substantia Nigra - Dopaminergic
      • Drug Therapy
        • L-DOPA
      • Pallidectomy
      • Tissue transplants ~
    • Huntington’s Disease (Chorea)
      • Rare
        • onset 30-40s
          • early as 20s
      • Degeneration of Striatum
        • Caudate
        • Putamen
      • GABA & ACh neurons ~
    • Symptoms
      • Khoros = dance
      • Uncontrollable, jerky movements
      • Dementia
      • Progressive
      • eventually fatal ~
    • SMA Putamen - - Subthalamic Nucleus + X Huntington’s Disease - + + VLo GP i GP e
    • Huntington’s Disease: Cause
      • Genetic disorder
      • Single dominant gene on chromosome 4
      • HD mutation -
      • unstable trinucleotide repeat - CAG
      • # of repeats correlated w/ age of onset ~
      • HD gene  huntingtin
      • 3 forms
        • mutated form binds to protein
        • involved in energy production
        • neuron starves
      • Excitotoxicity contributes to degeneration
        • glutamate  Nitric oxide (NO)
        • Potential treatment:: Inhibit NO synthase ~
      Huntington’s Disease: Cause
    • Hyperkinesia
      • Excessive movement
      • Ballism
        • violent, flinging movements
      • Lesions in subthalamus
        • less inhibition of VLo
        • excitation of SMA ~
    • SMA Striatum - X Hyperkinesia (e.g. ballism) Globus Pallidus - + VLo Subthalamic Nucleus +