Trends in Motor Control

1. Spring 2010 Trends in Motor Control

2. S-R approaches (Black Box) Hierarchical models (Active Processor) Dynamic systems (Dynamic interplay among systems) Study of Motor Behavior in the 20th Century

3. Prior to the 1900’s – introspection and self report measures • Turn of the century – observable only • S-R tradition • Bernstein’s work • Interactions of brain, body, and movement • World War II – Profound effects of motor control work

4. After World War II • Emphasis shifted to teaching, transfer, and retention • Late 40’s • Craik – Information Processing • Brain – computer relationship • Welford • Single Channel Processing • Psychological Refractoriness

5. Poulton’s work on anticipation and prediction in the 1950’s • Effector • Receptor • Perceptual • Fitts’ Law • Speed Accuracy Tradeoff (Length and width • Movement time • Movement extent • Movement accuracy

6. In stimulus response models the stimulus triggers a chain of individual reflex circuits that create a response. In this view is a passive recipients responding to the stimuli present in the environment and to which he or she is confronted Goal directed???? S-R Theory

7. Motor programs began with the definition of a fixed set of commands that could be structured prior to movement initiation. Schmidt (1975, 1991) provided the concept of a generalized motor program (GMP). “…existence of parameters, some variant, some invariant, that are applied to the GMP in order to specify how a particular movement pattern is to be expressed. These parameters specify overall duration of a movement, the overall force need to accomplish the movement, the temporal phasing of the movement pattern and, the spatial and temporal order in which the components of the movement are to be executed” (Schmdt, p. 5) Hierarchical models

8. Henry Adams Schmidt Bernstein Turvey Kelso Thelen Hierarchical control mechanisms Dynamic control mechanisms

9. A fixed program that can be run off uninterrupted by peripheral feedback. “The little man inside the head” How is the motor program defined?

10. Memory drum theory • “This is because a more comprehensive program i.e., a larger amount of stored information, will be needed, and thus the neural impulses will require more time for coordination and diretion into the eventual motor neurons and muscles” (Henry & Rogers, 1960, p. 450). • Henry and Rogers (1960) would have argued that a more complicated movement is dependent on the complex search and ordering of the subroutines thereby affecting the reaction time to a stimulus. Henry and Rogers (1960)

11. Chaos Theory Complexity Theory Coordinative Structure Theory Dynamic Pattern Theory

12. Perception/action model Invariant motor behavior Coordinative structures and dissipative structures Ecological approach Perturbation Attractor state Affordances Dynamic Systems Approach

13. Dynamic systems focus on the interaction between the performer and the environment. Dynamic systems differ from information processing systems by the way the action is produced. The dynamics result from the interaction of neurological, biological, musculoskeletal systems. These constantly change. Dynamic systems are emergent. Dynamic Systems

14. In a self-organizing system no subsystem has higher order control. The model is not a hierarchical one. A Dynamic System is Self-organizing

15. “… The process by which an individual constrains or, condenses his or her available degrees of freedom into the smallest number possible to achieve the goal… (Rose, 1996; P11). Coordination

16. Synergies result from organizational structures that coordinate the degrees of freedom for a particular movement. Some are ready-built and available at birth but the majority are developed throughout the lifespan and learned. Muscles are not controlled individually but are functionally linked with other muscles so as to form autonomous systems. Coordinative Structures or Synergies

17. Movements Emerge from Constraints Organism Environment Task

18. Anatomical • E.g., pectoralis major adducts the arm except when the angle of the arm is above the shoulder then contraction of the pectoralis major abducts the arm • Mechanical • Relationship between the state of the muscle and the movement sequence • Gravity • Inertia • Physiological • The motoneuron responds to signals from the brain and the spinal cord (which work together). Context specific variables (Bernstein)

19. Experts have less oscillation that novices.

20. http://www.pbs.org/wnet/nature/episodes/moment-of-impact/video-full-episode-part-2-jungle/5640/http://www.pbs.org/wnet/nature/episodes/moment-of-impact/video-full-episode-part-2-jungle/5640/

21. dynamics