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Making Things Happen Simple Motor Control

How Your Brain Works - Week 6 Dr. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net. Making Things Happen Simple Motor Control. “Efferents and Effectors”. “Efferent” nerves carry impulses “away” from the central nervous system.

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Making Things Happen Simple Motor Control

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  1. How Your Brain Works - Week 6 Dr. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net Making Things HappenSimple Motor Control

  2. “Efferents and Effectors” • “Efferent” nerves carry impulses “away” from the central nervous system. • Eventually they have to end either in muscles or in glands. • Physiologists distinguish 3 types of muscle: “smooth”, “cardiac” and “striate” (or skeletal”)

  3. Skeletal Muscle • There are ca 640 skeletal muscles in a human body

  4. Nervous Control of Skeletal Muscle Motor Cortex Basal Ganglia Cerebellum Spinal Cord Muscle

  5. muscle fibres axons muscle Muscle Fibre Structure

  6. Organisation of Muscle Fibres (actin) (myosin)

  7. Ca++ exposes Myosin Binding Sites

  8. The Myosin Cycle 1 2 • Myosin binds to actin. • Myosin head bends backward, releasing ADP and pulling itself forward. • ATP binds to myosin, causing release from actin. • Myosin uses energy from ATP hydrolysis to stretch itself, ready to undergo new binding and pulling cycle. 4 3

  9. Motor Units

  10. Muscle Spindles

  11. The Stretch Reflex

  12. Muscles tend to be arranged in pairs • Muscles can only contract. • If one muscle bends a limb (the “flexor”) then there must be another muscle to stretch it (the “extensor”). • Muscles are therefore typically arranged in agonist-antagonist pairs.

  13. Spinal Cord Antagonist Circuits Matthews “Neurobiology” Figure 8-3

  14. Postural support through spinal reflexes

  15. Spinal Pattern Generators

  16. Spinal cord pattern generators

  17. Headless Chicken • Warning: some viewers may find the content of this video clip distressing.

  18. Break

  19. Motor Related Areas of Cortex Supplementary Motor Area Frontal Eye Fields Primary Motor Cortex Somatosensory Somatosensory Somatosensory Cortex Cortex Cortex Broca’s Area Premotor Area

  20. Penfield’s Homunculi

  21. The Cortico-spinal Tract

  22. Motion Direction Sensitivity in Monkey Primary Motor Cortex • Georgopoulos et al, Science 1986

  23. Silicon Array Electrodes

  24. Primate moving robot arm

  25. Human Primate Matthew Nagel

  26. What about “Higher Order” Motor Cortex? Supplementary Motor Area Frontal Eye Fields Primary Motor Cortex Somatosensory Somatosensory Somatosensory Cortex Cortex Cortex Broca’s Area Premotor Area

  27. Mirror Neurons

  28. Broca’s Area • Broca’s aphasia is usually associated with lesion to the left frontal cortex. • See here the brain of Broca’s Patient, Mr Leborgne (“TanTan”) features a large lesion in Broca’s area.

  29. Motor Aphasia

  30. Motor Aphasia 2

  31. Wernicke’s Area • Wernicke’s aphasias are often associated with lesions at the boundary of the superior temporal and parietal lobes on the left hemisphere.

  32. A Patient with Wernicke’s Aphasia • From the archives of the University of Wisconsin

  33. The Arcuate Fasciculus Big fibre bundle connecting Broca’s and Wernicke’s Areashttp://www.biocfarm.unibo.it/aunsnc/pictef14.html

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