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Motor cortical areas: the homunculus

Motor cortical areas: the homunculus. The motor system. Major Cortical areas involved in planning and execution of “purposeful” movements. P.D. Directional Tuning of MI Cells. Movement onset. (Georgopoulos et al 1982). Set related responses in Pre-motor Cortex. Prepare LEFT movement.

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Motor cortical areas: the homunculus

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  1. Motor cortical areas: the homunculus The motor system

  2. Major Cortical areas involved in planning and execution of “purposeful” movements

  3. P.D. Directional Tuning of MI Cells Movement onset (Georgopoulos et al 1982)

  4. Set related responses in Pre-motor Cortex Prepare LEFT movement Prepare RIGHT movement

  5. Mirror neurons Rizzolatti et al., 1996

  6. Basic properties of the Mirror Neurons Rizzolatti et al. 1996

  7. A multimodal representation of action

  8. Mirror neurons in the Parietal cortex: Intention understanding?

  9. Mirror neurons show the same specificity when actions are preformed by the experimenter

  10. What is represented by the MN?Actions or goals? unit210 unit199 opening Hand Umlita et al., 2008 closure

  11. The mirror system – abstract representation of movement goals? • Recordings from 37 mirror neurons in F5 in a “hidden action” paradigm • 19/37 mirror neurons responded significantly in the hidden condition. • 7/19 – strong responses (hidden=visual) Full vision Hidden vision (Umilta et al., 2001).

  12. The mirror system in humans

  13. Cortical activation during observation of mouth hand and foot action

  14. Viewed-Hand identity effects in parietal cortex Shmuelof & Zohary 2006

  15. Visual and motor hand areas in the human parietal cortex

  16. Specificity of visually defined “hand areas” to motor actions

  17. Human mirror system fMRI response Dinstein, J. Neuroscience (2008) Executed Observed

  18. Selectivity

  19. Hang loose mirror neuron The finger mirror neuron Hang loose Fist The finger Thumbs up

  20. Monkey mirror neurons Gallese, Brain (1996)

  21. A deeper understanding of “mirror like voxels”

  22. Mirror regions should be active both during viewing action and motor action Mirror neurons should show cross-modal adaptation

  23. Adaptation First presentation Repeated presentation

  24. Movement selective adaptation Repeats Non-repeats

  25. Visual adaptation Repeats Non-repeats Observe Observe Observe Observe

  26. Motor adaptation Repeats Non-repeats Execute Execute Execute Execute

  27. Cross-modal adaptation Repeats Non-repeats Execute Observe Execute Observe

  28. Cross-modal adaptation Repeats Non-repeats Observe Execute Observe Execute

  29. Rock paper scissors Dinstein 2008 Get extra $10 if you win more than you lose!

  30. Game Timeline Observe Time

  31. Game Timeline Observe Execute Time

  32. Game Timeline Observe Execute Time Repeat Non-repeat

  33. Game Timeline Observe Execute Time Repeat Non-repeat

  34. Game Timeline Observe Execute Time Repeat Non-repeat

  35. Game Timeline Observe Execute Time Repeat Non-repeat

  36. Game Timeline Observe Execute Time Repeat Non-repeat

  37. Game Timeline Observe Execute Time Repeat Non-repeat

  38. Visual adaptation Mirror system areas Green: observed non-repeat > repeat

  39. Motor adaptation Mirror system areas Purple: executed non-repeat > repeat

  40. Motor & visual adaptation Mirror system areas Yellow: overlap of motor and visual adaptation

  41. Motor & visual adaptation Mirror system areas Yellow: overlap of motor and visual adaptation No cross modal adaptation

  42. ROI Analysis

  43. Adaptation summary Selectivity for movements in “Mirror system” areas. Adaptation may be taking place in a single population of mirror neurons and/or in two separate populations of visual and motor neurons adapting independently. We now have a way of studying movement selective responses; the critical feature of neural populations involved in movement perception. Dinstein J. Neurophysiology 2007

  44. Classification Typical mirror region = ~ 300 voxels fMRI response Executed Observed

  45. Classification No specificity in the overall fMRI signal (across voxels) fMRI response Executed

  46. Classification Specificity in the fMRI signal (within voxels)

  47. Movement selective patterns Activation level Strong Weak

  48. Are patterns distinct & reproducible? Execute Execute Execute Trial #1 Trial #2 Trial #3 Trial #4 …. …. ….

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