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فصل سوم- فرضيه ها و استراتژيهاي حركات 3-1 Centeralism 3-2 Prepheralism 3-3 Motor Program 3-4 Equilibim Hypothesis 3-5 Impedance Control

فصل چهارم- حركتهاي متناوب و راه رفتنگيهاي راه رفتن ويژه 4-1 4-2 Cenral Pattern Generator

فصل پنجم- ياد گيري حركت و مدلهاي ارائه شده براي حركت 5-1 Motor Learning مدلهاي ارائه شده5-2

5-2-1 Internal Model 5-2-2 Smith Predictor 5-2-3 Model Predictive Control

فصل ششم- معلوليت و بيماريهاي حركتي 6-1 FES 6-2 Parkinson 6-3 Huntington 6-4 ALS

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 problematicSo...

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 activityfine needle electrodes (skin/muscle)

measure contraction involved in activity

EMG

EMG

THE NEUROBIOLOGICAL VIEW

1 skeletal system & muscles: movements possible2 spinal cord:

a)ctrl skeletal muscles in response to sensory info (reflexes)

b) implementation of motor commands3 brainstem:

integration & relay of motor and sensory info from brain & spinal cord and in reverse, respectively4 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

Associative Cortex

Cerebellum Motor Cortex Basal Ganglia

Spinal Cord

Musculo-Skeletal System

Movement

Motor Program

Need

Plan

Highest Level

Lowest Level

MiddleLevel

VOLUNTARY MOVEMENTS vs REFLEXES

VOLUNTARY purposeful tasks open to experience/learningInternally generated (potentially) dissociated stimulus aspects : informational content-capacity to trigger movement (in higher motor system’s levels)

REFLEXES stereotyped stimulus-response relationshipenvironmentally triggeredstimulus aspects linkedorganized 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 generatedConnected 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 inhibitedLimb 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 appearanceM.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)