Dynamics of Bernstein’s Level of Synergies

1. Dynamics of Bernstein’s Level of Synergies Presentation by Susan & Joaquin

2. Readiness • Take out a piece of paper • Draw a picture depicting one of the five challenges to the level of synergies • Underneath your picture, define the level of synergies and explain how your picture depicts a challenge to the level of synergies

3. Class Objectives • Explain the benefits and drawbacks of the level of synergies • Identify all five challenges for the level of synergies, and provide specific examples for at least three of them • Explain the importance of rhythm to the level of synergies

4. What is the Level of Synergies? • Level B, known as the level of muscular-articular links • Why important? • No other level able to control large-scale movements (running/jumping/swimming) • Able to produce rhythmic movements, leading to cycles and automation (minted coins) • Downsides? • Needs help from other levels C and D to function in environment

5. Review of Levels

6. Five Challenges For The Level of Synergies

7. Challenge 1 • How to select the pattern of agonist and antagonist muscles that will produce a given movement trajectory • Movement of any limb requires the use of 2 muscles from that region • Work as agonists or antagonists depending on angle • Agonist = together • Antagonist = away • Example: arm wrestling

8. Challenge 2 • How to bring about muscular synchronization in which different muscles must contract by different amounts in equal time • Reaching for something • requires a linear angle, the • hand moves in a straight line • Straight-line movements • decrease directional changes • which may cause a loss of balance

9. Force must be applied to move an object from one specific point to another. This is done simpler if paths are straight lines because they will create smoother movements. • 2 different techniques:

10. Challenge 3 • How to bring about segmental synchronization, so that limbs and limb segments with different frequency preferences move at the same frequency • There is a competition between limbs • Arms and legs have different weights, and if detached would swing at different speeds • A compromise must • be made for success

11. Challenge 4 • How to separate timing from power, pattern from energy • Mvmt demands will determine level of synergies • 4 legged animals (cats, dogs, horses) have ability to walk, trot, or gallop either at low/high speeds

12. For each movement, the 4 limbs must pass through their respective cycles in sequential time. • The movements of the limbs and limb parts cannot move all at once and therefore need to be told by the brain centers when and how to move a particular limb

13. Challenge 5 • How to make the component degrees of freedom correct themselves to ensure pattern retention • Synergy must be self-organizing system • Must have a mutual understanding of how to take care of its own degrees of freedom • Must be able to correct itself when its pattern is interrupted

14. Nearly Decomposable Systems • The exchange of actions within a subsystem are usually heavy, but the exchange of actions between subsystems tend to be light. • Subsystems tend to work independently of each other • Primarily, the high-frequency behavior of a subsystem is independent of the high-frequency behavior of other subsystems • Secondly, the behavior of a certain subsystem relies on the actions of other subsystems with which it comes in contact with.

15. Rhythm • Successful cycles of a repeated act are like “minted coins” • Bernstein gives 5 reasons rhythm is compelling • Are ubiquitous in living systems • Explains how the nervous system organized movements and resolves efficiency of motion • Obeys simple rules, yet parts involved are complex • Evolve with different levels of variation • Oscillations (fluctuations) are dynamic

16. Von Holst’s Fish • Fish swim by fin movements, body is still • Absolute coordination: fins move @ same frequency • No coordination: Each fin moves @ own frequency -Relative coordination: Fins constant, then wander, then return to mutual attraction and frequency

17. Fish Experiment • Von Holst surgically cuts fish to control the nervous system He discovers the components of a synergy : (A) Compete (the maintenance tendency) (B) Combine (superimposition) (C) Cooperate (the magnet effect)

18. (A) In absolute coordination, the maintenance tendency states that if one fin were to be interrupted, the other fin would continue with it’s normal cycle. • Therefore, the fins of a fish are always competing with each other. • (B) In relative coordination, superimposition is present when numerous rhythmic synergies are active which causes the behavior of a synergy to be dependent of others • automatic adjustments are made among other subsystems comprised of any large-scale synergy • produce more detailed rhythmic synergies by combining simple rhythmic synergies

19. (C)The magnet effect determines and maintains the frequency and phase relations among components. • As two fins beating with different frequencies and with different amplitudes, frequencies united, but amplitudes remained unchanged

20. Contribution to Dexterity • Bernstein says dexterity requires minimum of two levels of the movement hierarchy • Leading level: switches among patterns and adjusts as needed • Background level: contributes harmony, precision and obedience • Example: Rider (leader): quick-witted Horse (background): obedient

21. Skills involve the level of actions (D) as the leading role, and the level of synergies (B) as the background role • Rider: has definite goals in mind and clearly identified paths to travel • Horse:has other constraints that must be satisfied • Success = satisfying constraints for the horse

22. End of Presentation

23. 5 Challenges • How to select the pattern of agonist and antagonist muscles that will produce a given movement trajectory • How to bring about muscular synchronization in which different muscles must contract by different amounts in equal time • How to bring about segmental synchronization, so that limbs and limb segments with different frequency preferences move at the same frequency • How to separate timing from power, pattern from energy • How to make the component degrees of freedom correct themselves to ensure pattern retention

24. Review of Objectives • Explain the benefits and drawbacks of the level of synergies • Identify all five challenges for the level of synergies, and provide specific examples for at least three of them • Explain the importance of rhythm to the level of synergies