Transcript No Slide Title

1- 1
1- 2
2- 2
3- 2
1- 3- 2
2- 3- 2
3- 3- 2
4- 2
1- 4- 2
2- 4- 2
3- 4- 2
4- 4- 2
‫ فرضيه ها و استراتژيهاي حركات‬-‫فصل سوم‬
Centeralism 1-3
Prepheralism 2-3
Motor Program 3-3
Equilibim Hypothesis 4-3
Impedance Control 5-3
‫ حركتهاي متناوب و راه رفتن‬-‫فصل چهارم‬
‫ ويژه گيهاي راه رفتن‬1-4
Cenral Pattern Generator 2-4
‫ ياد گيري حركت و مدلهاي ارائه شده براي حركت‬-‫فصل پنجم‬
Motor Learning 1-5
‫ مدلهاي ارائه شده‬2-5
Internal Model 1-2-5
Smith Predictor 2-2-5
Model Predictive Control 3-2-5
‫ معلوليت و بيماريهاي حركتي‬-‫فصل ششم‬
FES 1-6
Parkinson 2-6
Huntington 3-6
ALS 4-6
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
HUMAN MOTOR CONTROL SYSTEM
Overview
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
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
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...
MOTOR PLANS/PROGRAMS
complex movements & acts produced and
controlled by set of commands to muscles,
established before onset. Feedback on execution
THE CONTROL SYSTEMS VIEW
 Machine design vocabulary: accuracy and speed
criteria
 Closed-loop and Open-loop ctrl mechanisms to
optimize performance
CLOSED-LOOP CTRL MECHANISMS
 continuous feedback from controlled system to
controller (e.g. driving)
 slow, sustained movements (ramp/smooth)
 accuracy & flexibility at speed expense
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)
MOTION ANALYSIS & MEASUREMENT
 photographic, computer graphic techniques
 EMG (electromyography):
recording muscle electrical activity
fine needle electrodes (skin/muscle)
 measure contraction involved in activity
EMG
EMG
THE NEUROBIOLOGICAL VIEW
1 skeletal system & muscles: movements possible
2 spinal cord:
a)ctrl skeletal muscles in response to sensory info
(reflexes)
b) implementation of motor commands
3 brainstem:
integration & relay of motor and sensory info from
brain & spinal cord and in reverse, respectively
4 primary motor cortex (M1):
motor commands initiation
THE NEUROBIOLOGICAL VIEW ctnd
5 premotor cortex:
programs levels of motor cortical processing
6 basal ganglia & cerebellum:
modulate activities of hierarchically organized
motor ctrl systems
Limbic System
Highest
Level
Need
Associative Cortex
Plan
Cerebellum
Motor Cortex
Basal Ganglia
Middle
Level
Motor Program
Spinal Cord
Musculo-Skeletal
System
Movement
Lowest
Level
VOLUNTARY MOVEMENTS vs REFLEXES
VOLUNTARY
REFLEXES
 purposeful tasks
 stereotyped stimulus-response
relationship
 open to experience/learning
Internally generated (potentially)
 dissociated stimulus aspects :
informational content-capacity to
trigger movement (in higher motor
system’s levels)
environmentally triggered
stimulus aspects linked
organized in spinal & brain stem
circuits in response to
somatosensory, vestibular stimuli
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)
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]
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)