Motor Control – Rapid Review

Sensory Components of Motor Control

  • Touch: mechanoreceptors supply pain, temp, movement cues ➔ support movement accuracy, consistency, timing, force, distance\text{accuracy, consistency, timing, force, distance}
  • Proprioception: CNS afferents from
    • Muscle spindles – detect length change
    • Golgi-tendon organs – detect tension/force
    • Joint receptors – extremes of joint angle
      Roles: movement accuracy, command onset, coordination
  • Vision
    • Eye optics: cornea, pupil/iris, lens
    • Neural: retina (rods – low light/periphery; cones – colour/acuity), optic nerve/chiasm
    • Processing: monocular vs binocular; central vs peripheral fields

Movement Performance Principles

  • Speed-Accuracy Trade-off: faster → less accurate; modelled by Fitts’ law
    MT=a+blog⁡2(2DW)MT = a + b \log_2\left(\frac{2D}{W}\right)
  • Manual aiming phases
    1. Preparation – visual analysis of target
    2. Initial flight – rapid transport (~95%95\% MT)
    3. Termination – vision-guided corrections
  • Prehension: transport + grasp + manipulation; temporal coupling; adapts to object change
  • Bimanual coordination: symmetric easier; asymmetric requires practice & feedback

Locomotion & Rhythmic Coordination

  • Central Pattern Generators produce alternating limb rhythm
  • Gait transition speed triggers walk→run strategy shift
  • Vision + proprioception set foot placement; head stability preserves visual reference

Action Preparation & Reaction Time

  • Reaction Time (RT) = interval stimulus→movement start; reflects preparation
  • Influences
    • Choices: Hick’s law RT=a+blog⁡2(N)RT = a + b \log_2(N)
    • Complexity, S-R compatibility, predictability, foreperiod regularity, repetition
  • Donders: stages—detect, discriminate, select, initiate

Attention

  • Limited capacity (Kahneman central pool; multiple resources – modality, stage, code)
  • Allocation rules: ensure primary task, enduring dispositions (novel/meaningful), momentary intentions
  • Visual selective attention: eye shifts follow attentional shifts; rely on relative motion cues (feature-integration theory)

Memory Essentials

  • Working memory: ≈20s,7±2\approx20\text{s}, 7\pm2 items; subsystems—phonological loop, visuospatial sketchpad, central executive; use chunking
  • Long-term memory:
    • Procedural (motor), Semantic (facts), Episodic (events)
  • Forgetting: trace decay, proactive & retroactive interference
  • Improvement strategies: meaningfulness, intention, subjective organization

Motor Skill Learning

  • Performance vs Learning: learning inferred from persistent improvement, consistency, stability, adaptability, ↓attention
  • Fitts & Posner stages
    • Cognitive → Associative → Autonomous
  • Gentile: Initial (movement pattern + regulatory cue discrimination) → Later (fixation for closed / diversification for open skills)
  • Bernstein: freeze DOF → release → exploit dynamics; final standardization & stabilization

Transfer of Learning

  • Positive, Negative, Zero
  • Causes: identical elements (Thorndike), automatisms (Bernstein), transfer-appropriate processing (similar cognitive demands)
  • Negative transfer common with spatial reversal or timing change

Demonstration & Verbal Instruction

  • Observational learning uses relative motion; mirror-neuron system supports rehab
  • Effective demos focus learner on movement outcome not individual joints

Augmented Feedback

  • Intrinsic vs Augmented
    • KR: outcome; KP: movement pattern (descriptive vs prescriptive)
  • Roles
    • Essential when intrinsic cues absent/unusable
    • Enhances if adds actionable info
    • Hinders if over-reliance (concurrent feedback dependency)
  • Timing: concurrent (risk dependency) vs terminal (reflection)

Practice Conditions

  • Variability: varying movement & context improves test performance; implement via closed-skill parameter shifts / open-skill env change
  • Schedules
    • Blocked (low CI) ➔ good practice, poor retention
    • Random (high CI) ➔ slower practice, better retention/transfer
  • Overlearning: extra practice past criterion strengthens retention but may hurt problem-solving tasks
  • Distribution
    • Massed = short rest; Distributed = long rest ➔ better long-term retention
  • Whole vs Part
    • Use whole for low-complexity/high-organization skills
    • Use part (fractionization, segmentation, simplification) for high-complexity/low-organization
  • Attention-focus part practice: execute whole while focusing on one component
  • Mental Practice: imagery rehearsal (visual + kinesthetic) enhances cognitive planning; most effective combined with physical practice; supported by neuromuscular & brain-activity evidence