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Cogsci/Psychology 127: Lecture 11 Motor Pathways and Disorders

Cogsci/Psychology 127: Lecture 11 Motor Pathways and Disorders. Anatomy of Motor Pathways: Primary Motor Area. Motor Cortex. Pyramidal Tract (corticospinal) 90% Crossed; 10% Uncrossed Direct control of individual muscles. Internal capsule. Pyramidal Tract (corticospinal)

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Cogsci/Psychology 127: Lecture 11 Motor Pathways and Disorders

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  1. Cogsci/Psychology 127: Lecture 11Motor Pathways and Disorders

  2. Anatomy of Motor Pathways: Primary Motor Area Motor Cortex

  3. Pyramidal Tract (corticospinal) 90% Crossed; 10% Uncrossed Direct control of individual muscles Internal capsule

  4. Pyramidal Tract (corticospinal) 90% Crossed; 10% Uncrossed Direct control of individual muscles 4th finger problem Internal capsule

  5. Anatomy of Motor Pathways: Secondary Areas Supplementary Motor Area (SMA) Premotor Cortex

  6. Anatomy of Motor Pathways: Association Areas Pre-SMA

  7. Anatomy of Motor Pathways: Subcortical Areas

  8. Pyramidal Extrapyramidal (origin in motor cortex, premotor, parietal origin)

  9. Anatomy of Motor Pathways: Spinal Cord

  10. Disorders of the Motor System Motor Cortex (and pyramidal tract) Hemiplegia: Paralysis of contralateral limb(s)

  11. Disorders of the Motor System Motor Cortex (and pyramidal tract) Hemiplegia: Paralysis of contralateral limb(s) Hemiparesis: Weakness, impaired control of contralateral limb(s)

  12. Disorders of the Motor System Motor Cortex Hemiplegia Hemiparesis Secondary/Association Motor Areas Apraxia: Loss of ability to generate coordinated actions NOT due to loss of muscle control Problems in making coordinated gestures e.g., whistling, saluting, blowing out match Especially apparent when miming actions

  13. Disorders of the Motor System Motor Cortex Hemiplegia Hemiparesis Secondary Motor Areas Apraxia: Ideomotor Difficulty in carrying out commands, producing coherent actions, esp. with complex sequential actions. CN Tape: 2:23:30 – 2:26:25 (21.2) (also Apraxia Tape: 32:45 – 35:30) Apraxia Tape: 00:15 – 3:00

  14. Disorders of the Motor System Motor Cortex Hemiplegia Hemiparesis Secondary Motor Areas Apraxia:Ideomotor Ideational Loss of knowledge about actions and how they are used to manipulate objects. Video Clips Apraxia Tape: 10:20 - 11:45, 12:00 – 12:55, 13:00 – 15:38

  15. Disorders of the Motor System Motor Cortex Hemiplegia Hemiparesis Secondary Motor Areas Apraxia:Ideomotor Ideational Anatomy: Observed with premotor, prefrontal, or parietal lesions. Usually Left Hemisphere.

  16. Motor Test of Apraxia Perception test of action comprehension: Which picture shows how to hold hand to open a door with a key?

  17. Traditional Model of Action Representation "Left hemisphere contains movement formulas that bilaterally program the selection, timing, and spatial relationships of skilled movements." -- Liepmann and Maas 1907

  18. Left hemisphere and praxis. • Relationship to aphasia? • Do apraxic patients have problem specific to coordination (apraxia) or is this secondary to problem with comprehension (aphasia) • Video Clip: Apraxia Tape: 15:56 – 19:20 • End when patient succeeds on Stop Command

  19. Left Hemisphere Specialization for Praxis (movement) Is apraxia an epiphenomenon, secondary to aphasia? Severity of apraxia is highly related to severity of aphasia (but not the reverse)

  20. Handedness and praxis in normal individuals Index Finger Tapping: LH and RH DEMO

  21. Handedness and praxis in normal individuals Sequential Movements: LH and RH DEMO

  22. Left Hand Left Hand Right Hand Right Hand Taps Per Second Left Right Handers Handers Handedness and praxis in normal individuals As movements become more complex, role of left hemisphere becomes more apparent. Index Finger Tapping Sequential Movements Taps Per Second Left Right Handers Handers

  23. Handedness and praxis in normal individuals fMRI: Sequential Movements versus Rest Right Hand Left sensorimotor Left posterior parietal SMA Bilateral prefrontal Bilateral premotor

  24. Handedness and praxis in normal individuals fMRI: Sequential Movements versus Rest Right Hand Left Hand Left sensorimotor Left posterior parietal SMA Bilateral prefrontal Bilateral premotor Right sensorimotor Left posterior parietal ** Left precentral gyrus ** SMA Bilateral prefrontal and PM

  25. Handedness and praxis in normal individuals fMRI: Sequential Movements versus Rest Right Hand Left Hand Left handers show same pattern as right handers. Asymmetry in ipsilateral activation is associated with hemispheric specialization rather than hand dominance.

  26. Computations required for skilled actions that might draw on left hemisphere specializations. Sequential representations.

  27. Computations required for skilled actions that might draw on left hemisphere specializations. Sequential representations. Tool use fMRI activation during planned tool use Right Hand Movement Left Hand Movement

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