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Issues in Motor Control

Issues in Motor Control. Serial Order and Timing Problem Degrees of Freedom Problem Perceptual-Motor Integration Problem Learning Problem. (Rosenbaum, 2002). Earlier Ideas Used Response Chaining: Closed (feedback)-Loop Control:. No, because delays too long between movements

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Issues in Motor Control

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  1. Issues in Motor Control • Serial Order and Timing Problem • Degrees of Freedom Problem • Perceptual-Motor Integration Problem • Learning Problem (Rosenbaum, 2002)

  2. Earlier Ideas Used Response Chaining: Closed (feedback)-Loop Control: • No, because • delays too long between movements • disrupting feedback does not necessarily impeded movement • Systematic mistakes in speech, typing, etc “He hissed all my mystery lessons” rather than “he missed all my history lessons”

  3. Closed-Loop Control: Still Occurs • Can you think of an example? • Muscle spindle (20-30 ms) • Long-loop reflexes

  4. Closed-Loop Control: Still Occurs http://www2.fhs.usyd.edu.au/ess/odwyer/Human%20Motor%20Learning%20and%20Control/Lectures/Week%206/Using_Information_FF_vs_FB_Control.pdf

  5. Need for Closed and Open-Loop Systems http://www2.fhs.usyd.edu.au/ess/odwyer/Human%20Motor%20Learning%20and%20Control/Lectures/Week%206/Using_Information_FF_vs_FB_Control.pdf

  6. Perceptual-Motor Integration: Tasks • Arbitrary or incompatible mappings (see later section on S-R compatibility) • Tracking tasks • Prism spectacles click here

  7. Open-(feedforward) Loop Control • Anticipatory Control • Predictive Control • Prospective Control

  8. Issues in Motor Control • Serial Order and Timing Problem • Degrees of Freedom Problem • Perceptual-Motor Integration Problem • Learning Problem (Rosenbaum, 2002)

  9. Solving the Serial Order Problem: using Open-Loop Control: Plans or Programs • Evidence for planning movements in advance • Reaction Time approach http://www2.fhs.usyd.edu.au/ess/odwyer/Human%20Motor%20Learning%20and%20Control/Lectures/Week%206/Using_Information_FF_vs_FB_Control.pdf

  10. Serial Order and Timing Problem: The Questions • How do we specify ordinal features of movements? • Do we use ratio, interval, or both values for time?

  11. RT: Input-?-Output Movement Initiation GO = Reaction Time

  12. Parallel Processing Cascade Processing

  13. Influences on RT RT is a volatile measure which is sensitive to many factors: • stimulus factors: • modality of presentation (visual, auditory, tactile, kinaesthetic) • intensity (loudness, brightness) • temporal predictability • number of response choices • stimulus-response compatibility • response complexity SRT CRT SRT

  14. stimulus factors impacting SRT: • modality of presentation (visual, auditory, tactile, kinaesthetic) • intensity (loudness, brightness) • temporal predictability

  15. Event Uncertainty and CRT • Number of response choices • Probability Effects • Precues • Sequential Effects

  16. Hick’s Law CRT = a + b (log2 N) # Decisions CRT = SRT + DT (# Decision)

  17. Precues What is being precued? Where is the impact? CRT = SRT + DT (# Decision)

  18. Reducing Event Uncertainty: Probability Effects

  19. Decision Time CRT = SRT + DT (# Decision) Stimulus-Response Compatibility • Degree of correspondence between the stimulus array and the response

  20. CRT = SRT + DT (# Decision)

  21. Motor Programming: What movement parameters must be planned?

  22. Henry and Roger (1960) MT (ms) 0 95 465 208 Keep in mind that the RT for the finger lift is being measured here not MT: What movement parameter(s) were responsible for increase in RT

  23. Using Henry & Rogers data: What are the key movement parameters that need to be planned? • Movement Duration • Number of Elements (sequence length effects) • Changes in Direction • Force/velocity requirements • Directions requirements

  24. Speech Motor Programming Intercept is cost of the word complexity ~180 vs. ~100 ms Slope is cost of programming more items (~12 ms) • Impact of Programming # of • syllables within a word (intercept) • Impact of programming # of • Words (slope)

  25. Can we accomplish this? What does this mean? 0 ms intercept 0 ms DT Event Certainty √ Temporal Certainty √ ANTICIPATION

  26. Programming Timing: Variability Measures Krampe, et al., in press

  27. Krampe, et al., in press

  28. Two Important findings: • greater slope for complex rhythm • slope for complex rhythm is age sensitive

  29. Closed vs. Open Loop Plans or Motor Programs Quantifying the plan: Reaction Time The plan (or RT) involves: Perception-Response Selection-Programming Verifying this model by finding factors impacting Perception-Response Selection-Programming (c)Rt = SRT + DT(# of Decisions)

  30. (C)RT = SRT + DT(# of Decisions) Movement Duration Number of Elements (sequence length effects) Changes in Direction Force/velocity requirements Directions requirements • Modality of presentation • intensity (loudness, brightness) • temporal predictability Perceptual Process Motor Programming • Compatibility of S and R • Practice • Number of Alternative • Precues • Sequential dependencies Decision Making (response selection)

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