31 Centeralism

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??? ???- ????? ?? ? ??????????? ????? 3-1
?Centeralism 3-2 Prepheralism 3-3 Motor
Program 3-4 Equilibim Hypothesis 3-5
Impedance Control ??? ?????- ??????? ?????? ?
??? ???? 4-1 ???? ????? ??? ???? 4-2 Cenral
Pattern Generator ??? ????- ??? ???? ???? ?
?????? ????? ??? ???? ???? 5-1 Motor
Learning 5-2 ?????? ????? ??? 5-2-1
Internal Model 5-2-2 Smith Predictor
5-2-3 Model Predictive Control ??? ???- ???????
? ????????? ????? 6-1 FES 6-2 Parkinson
6-3 Huntington 6-4 ALS
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References

• 1-Neurological Control Systems Studies in
  Bioengineering ,Stark L, 1968-
• 2-Muscle Alive, Basmajian JV
• 3- The Neural Basis of Motor Control, Brooks, V.
  B., (1986). Oxford Univ. Press.
• 4-Multiple Muscle Systems, M. Winters and S. L-Y.
  Woo (ed.), Springer-Verlag (1990)
• 5-Motor Control Theory and Practical
  Applications by Anne Shumway-Cook, Marjorie H.
  Woollacott
• 6- Motor Control And Learning A Behavioral
  Emphasis, Fourth Edition by Richard Schmidt, Tim
  Lee
• 7- Motor Learning and Performance by Richard A.
  Schmidt, Craig A. Wrisberg
• 8- The Computational Neurobiology of Reaching and
  Pointing By Reza Shadmehr and Stiven P. Wise, MIT
  Press, 2005

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HUMAN MOTOR CONTROL SYSTEM
Overview
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MOTOR BEHAVIORS CLASSIFIED ON FUNCTIONAL
PROPERTIES
Movements brief,discrete, unitary muscle
activities, limited to single parts
Acts complex, sequential behaviors,
goal-oriented, different body parts included
(action patterns)

• more restricted CNS regions that ctrl movements
  than acts

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QUESTION OF BASIC UNITS OF MOVEMENTS
Reflexes simple, highly stereotyped and
unlearned responses to external stimuli. Their
magnitude related to stimulus intensity.
Spinal cord roots dorsal contain sensory fibers,
ventral contain motor fibers
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Some reflexes short pathways in spinal cord
linking dorsal ventral roots, others longer
loops (spinal cord interconnections or to the
brain)
Reflexes as basic units of movement (Sherrington,
early 20th century)
BUT Speech as ordered stimulus-response units
problematic So...
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MOTOR PLANS/PROGRAMS
complex movements acts produced and controlled
by set of commands to muscles, established before
onset. Feedback on execution
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THE CONTROL SYSTEMS VIEW

• Machine design vocabulary accuracy and speed
  criteria

• Closed-loop and Open-loop ctrl mechanisms to
  optimize performance

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• CLOSED-LOOP CTRL MECHANISMS

• continuous feedback from controlled system to
  controller (e.g. driving)
• slow, sustained movements (ramp/smooth)
• accuracy flexibility at speed expense

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OPEN-LOOP CTRL MECHANISMS

• activity preprogrammed
• sensor measured output(no external form of
  feedback
• rapid responses -ballistic movements (e.g.
  throwing a fastball)
• no feedback/ error reduction anticipation
  (prior learning)

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MOTION ANALYSIS MEASUREMENT

• photographic, computer graphic techniques
• EMG (electromyography)
• recording muscle electrical activity
• fine needle electrodes (skin/muscle)
• measure contraction involved in activity

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EMG
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EMG
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THE NEUROBIOLOGICAL VIEW

• skeletal system muscles movements possible
• spinal cord
• a)ctrl skeletal muscles in response to sensory
  info (reflexes)
• b) implementation of motor commands
• brainstem
• integration relay of motor and sensory info
  from brain spinal cord and in reverse,
  respectively
• primary motor cortex (M1)
• motor commands initiation

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THE NEUROBIOLOGICAL VIEW ctnd

• premotor cortex
• programs levels of motor cortical processing
• basal ganglia cerebellum
• modulate activities of hierarchically organized
  motor ctrl systems

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Limbic System
Highest Level
Need
Associative Cortex
Plan
Middle Level
Cerebellum
Motor Cortex
Basal Ganglia
Motor Program
Spinal Cord
Lowest Level
Musculo-Skeletal System
Movement
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VOLUNTARY MOVEMENTS vs REFLEXES

• VOLUNTARY
• purposeful tasks
• open to experience/learning
• Internally generated (potentially)
• dissociated stimulus aspects informational
  content-capacity to trigger movement (in higher
  motor systems levels)

• REFLEXES
• stereotyped stimulus-response relationship
• environmentally triggered
• stimulus aspects linked
• organized in spinal brain stem circuits in
  response to somatosensory, vestibular stimuli

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MUSCULAR CTRL OF ACTION OF SKELETAL SYSTEM

• muscles generate force by contraction
• springlike properties influence timing forces
  generated
• Connected to bones by tendons/ attachment
  indicative of mediated movement
• reciprocal arrangements around joints
  (flexion/extension) (e.g. arm biceps/triceps)-
  antagonists synergists (act together)
• coordinated action around joint might require
  set of motoneurons excited the antagonistic set
  inhibited
• Limb locked in position by contraction of opposed
  muscles
• body posture maintenance, movement around joint,
  other muscles not act on skeleton (abdomen
  contraction)

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• MUSCLE TYPES
• smooth (stomach) contractions regulated by
  autonomic system
• Skeletal under voluntary control

Muscle fibers overlapping filaments(made of
actin myosin) give the striped
appearance M.fibers single large cells with
many nuclei (thousands compose a
muscle) Contraction increases overlap(myosin
binds to actin, filaments slide past one
another)-length shortens
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MUSCLE FIBERS TYPES 1) fast for quick,
accurate not maintained movement (e.g.
extraocular muscles composed of those) 2) slow
resiliency to fatigue (posture maintenance)