1. Motor system basics

2. Motor Development

3. Motor neurons & Muscle fibers

4. Local motor control
Muscle spindles enforce the “stretch reflex”: feedback about muscle length.
Golgi tendon provide feedback about level of force.

5. Spinal chord

6. Central pattern generators
Taking care of the basic simple functions...

7. Central pattern generators

8. Central pattern generators
De-cerebrate walking cat

9. Postural control
Vestibular and Reticular nuclei (medial motor system).
Adaptation and Anticipation – Sailor “sea legs”

10. Voluntary control
Cortico-spinal and Rubro-spinal pathways (lateral motor system).
Fine motor control.
~ 1 Million fibers originating in:
Primary motor cortex (one third)
Premotor cortex (one third)
Somatosensory cortex (one third)

11. Somatotopic organization of M1

12. Motor system hierarchy

13. Motor system hierarchy
Performing actions is complicated…
Incorporate:
Visual information
Auditory information
Somatosensory information
Make a decision
Make a motor plan (timing, forces, balance, etc…)
Execute

14. Encoding of M1 neurons: Force

15. Encoding of M1 neurons: Direction
Textbook stories describe M1 neurons as responsible for the final motor execution step…

16. Higher motor levels Visual – movement performed according to cue.
Internal – movement performed as part of a memorized sequence.

17. Anterior parietal & Premotor cortex
Visuomotor coordination
Object manipulation
Grasping

18. Areas F5 and AIP/PF Canonical neurons – object specific actions
Regardless of where objects are located
Murata (1997, 2000)

19. Microstimulations Story is a bit more complex.
Long microstimulations in premotor, anterior parietal, and primary motor cortex generate complicated multi-effector movements.
Like grasp to eat…
Idea of motor primitives

20. Supplementary motor cortex
Neurons that respond to a specific movement only when it is part of a sequence (a) or to any movement, but only according to its location in the sequence (b).

21. Functional specialization
Damage in M1 creates weakness in the relevant part of the body.
Damage in parietal and premotor cortex creates problems with movement planning and coordination.
Damage in SMA creates problems with learning new movement sequences

22. Motor control So far we have talked about physiology.
What is the purpose of the motor system?

23. Encoding space
Head centered?
Hand centered?
Eye centered?

24. You need to translate external space to internal space…
Inverse model
You need to translate external space to internal space…

25. Inverse model
Eventhough you use different joints and muscles for different movements:
Movements remain straight, smooth, with symmetric velocity profile.
Your motor system cares about making smooth efficient movements in external space…
(Morasso 1981)

26. Motor primitives
Invariance to scale…

27. Motor primitives Invariance to effector…
Raibert 1977
Invariance to effector…
Similar brain solution to very different movements

28. Inverse model is flexible…
(Brashers-Krug, Shadmehr, and Bizzi 1996)

29. Inverse model is flexible…

30. Motor memory

31. Where does motor learning happen?

32. How do we study neurophysiology?

33. Dendrites Cell body Axon
חומר אפור ולבן, תאים וקישורים בין תאים - מיילין.
Axon

34. Neural activity

35. In vitro electrophysiology
Control > ASD

36. In vivo electrophysiology
Control > ASD

37. In vivo electrophysiology
Control > ASD
Anesthetized or awake

38. Electrode location
Control > ASD

39. Magnetic resonance imaging (MRI)

41. Anatomy - Separating tissues

42. Anatomy – Cortical thickness

43. Anatomy – Cortical folding

44. Anatomy – white matter
Tractography
Fiber volume
Fiber length

45. Brain function
Neurovascular coupling

46. Vasculature

47. Changes in oxygenated blood
זמן
Heeger et. al. 2002

48. fMRI experiment

50. In fMRI we always compare measures over time
Experimental results
In fMRI we always compare measures over time

51. Converging evidence
Good science is achieved by generating hypotheses that can be tested with different types of experiments in order to generate converging evidence.