7112195 motor control theories
TRANSCRIPT
Movement
Movement is a critical aspect of life.Life would not be possible without the
capacity to move. WHAT IS MOVEMENT ??
Motor Control
Types of Movements
Inherited or Self-Differentiated
Genetically definedEg: One’s control over their limbs
Movements
Learned
Not inherited and mastering them requires long periods and experience.Eg: Operating a typewriter
Motor Control
SKILLS
Learned Movements are termed as Skill Movements.
Guthrie: “Skill consists in the ability to bring about some end result with maximum certainty and minimum outlay of energy, or time and energy.”
Classification of Skill:– Depending on size of musculature required– Depending on specificity of where actions begin & end– Depending on stability of the environment context
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Fine Motor Skills
Size of primary Musculature Required
Gross Motor SkillsPrimary Musculature required = Large & Small
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1
Continuous Motor Skills
2
Serial Motor Skills
Specificity of where actions begin & end
3
Discrete Motor Skills
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Stability
Factors Constraining Movement
Mobility
Man
ipul
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n
T
I E
Regulatory
NonRegulatory
Cognition
Perception A
ctio
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Motor Control
Evolution of Motor Control
Emerged from two isolated bodies of knowledge:
• Branch of Neurophysiology (neural processes associated with Movements but not movements itself)
• Branch of Psychology & related fields (Concerned with high level skills with little reference to neurological mechanisms)
Motor Control
Evolution of Motor Control
Around 1820: Bessel (Astronomer)• Process underlying differences among his
colleagues in recording the transit times of the movements of stars.
1882: Bowditch & Southard• Studying hand movements in localizing targets
1892: Fullerton & Cattell• Examined force reproducibility
1899: Woodworth• Fundamental principles of rapid arm & hand
movements
Motor Control
Evolution of Motor Control
During middle and late 1800s:• Memory for movements• Speed-Accuracy Trade-Offs• Phase Transitions in Bimanual Movements
1914: Thorndike• Processes underlying learning skills & other
behaviors• Law of Effect (Responses followed by reward tend
to repeat)• Differences among individuals over practice
Motor Control
Evolution of Motor Control 1935 - 1940: Bayley, McGraw & others
• Started studying the area now known as Motor Development
1892 – 1895: Blix and Weber• Identified Characteristics & Contractile properties
of muscle tissue
1870s: Jackson• Investigations of neural control of movement
These contributions lead to evolution of Physiological or Neural bases of Movement
Motor Control
Evolution of Motor Control
1870: Fritsch & Hitzig
• Brain is electrically excitable and lead to development of electrophysiological techniques
1888: Ferrier• Investigated responses in the cortex to artificial
movements
1887, 1890: Beevor & Horsely• Sensory & Motor areas of Brain
Motor Control
Evolution of Motor Control Contribution by Sherrington
• Studied & classified major responses to stimuli presented to extremities
– Voluntary movements resulted from these fundamental reflexes
• Reciprocal Innervation: When flexors of a joint are activated, the extensors tend to be automatically deactivated, and vice versa.
– Golgi Tendon Organ: Signal changes in muscle tension– Muscle Spindle: Perception of muscle length & hence
joint position
• Proprioception: Sense of body position & orientation thought to be signaled by various muscle & joint receptors together with receptors located in the inner ear.
Motor Control
Evolution of Motor Control 1943: Hull
• Theories of Learning• How fatigue and recovery processes combined to
determine learning of motor skills
1948: Craik• Brain works as a computer (Information is
received, processed and then output to environment in the form of actions of limbs)
• Central Tendency: Humans responds in discrete bursts rather than continuous
1949: Wiener• Information Processing Theory
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Evolution of Motor Control
1954: Fitts• Fitts’s Law: Model of human movement which
predicts the time required to rapidly move to a target area, as a function of the distance to the target and the size of the target
1970s:• North American Society for the Psychology of
Sport & Physical Activity (NASPSPA)• Canadian Society for Psycho-Motor Learning &
Sport Psychology
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Motor Control Today
1967: Neisser• Stimulus-Response Theory:
1970 – 1989: Pew, Schmidt• Transition from Task Orientation to Process
Orientation– Task orientation focuses primarily on the effects of
variables on the performance of certain motor task– Process orientation focuses on the underlying mental or
neural events that support or produce movements
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Motor Control Today 1966: Adams & Dijkstra, Posner & Konick
• Short-term Memory which explained processes underlying memory loss in simple movements over short period of time.
1971: Adams• Feedback-based theory for motor learning
1974: Pew• Movement Schema: Abstract hypothetical
structures responsible for movement control & evaluation
1975: Schmidt• Presented the Schema Theory for learning simple
motor skills
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Motor Control Today After 1970s:
• Merger between Neural Control & Motor Behavior• Neural Mechanisms studies by experiments on
animals• Association between movement behaviors and
neurological processes which provided more complete understanding of how movements where controlled
• Development of advanced techniques– Electrophysiological recordings– Cinematographic & 3-D analysis– Measurements of kinematics of movement– Advanced methods examining involvement of brain
structures in learning
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Motor Control Today
Understanding of Degrees of Freedom Problem
• How system with many independent parts could be controlled without need for an executive decision marker
• Laws and principles for coordination and degrees of freedom
1995: Kelso• Dynamic Pattern Perspective suggested that
coordinated movements evolves over time as a function of interaction between body parts, and between the body parts and physical world.
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Motor Control TodayMotor Control
INPUTS FROM DR. CAURAUGHINPUTS FROM
DR. CAURAUGH
CURRENT INSIGHTSCURRENT INSIGHTS
Theories of Motor Control
Theory: Is a set of concepts, propositions, or definitions that are interrelated in some ways.
They are used to specify relationship among different variables so that we can obtain a systematic view of specific types of phenomena.
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Motor Control Theories
Most of the Motor Control Theories incorporate two basic systems of control.
Open-Loop Control System Closed- Loop Control System
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Open-Loop Motor Control System A set of muscle commands that are structured
before a movement begins that specifies a sequence to be carried out that is uninfluenced by peripheral feedback.
Advantages: The production of very fast movements in absence of
feedback Feedback does not have to be processed during
movements
Disadvantages: Not effective when environmental situations are
constantly changing Not good for very precise movements
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Closed-Loop Motor Control SystemMotor Control
INPUT
INPUT
SENSORY FEEDBACK
Movement Commands
Updated Movement Commands
Closed-Loop Motor Control System
Feedback can be used not only to plan and initiate movements but also to adjust progress in an ongoing movement.
Advantages: Allows for a great deal of movement flexibility Can be used to produce very accurate movements
Disadvantages: Execution of corrections tends to be attention
demanding Very time demanding so not applicable to open,
reactive sport situations.
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Motor Control Theories
Reflex Theory Ecological Theory Hierarchical Theory Motor Programming Theories System Theory Dynamical Action Theory
Motor Control
Reflex Theory
Charles Sherrington (Neurophysiologist) Reflexes are the building blocks
(fundamental units) of Motor Control. Reflexes worked together or in sequence
to achieve a common purpose. Physical events occurring in the
environment served as the STIMULUS for action, triggering chain of individual reflex circuits that were responsible for producing a movement RESPONSE.
Motor Control
Reflex Theory Reflex requires three basic structures:
Receptor• Sensory receptors in skin, muscles & joints and other
sensory systems
Conducting nervous pathway Afferent Nervous Pathway
• Carries impulses from receptors towards the CNS
Efferent Nervous Pathway• Carries impulses away from CNS to effector organs
Effector Organs Muscles
Motor Control
Reflex Theory
Sherrington concluded that with the whole nervous system intact, the reaction of the various parts of that system, the simple reflexes, are combined into greater actions that constitute the behavior of the individual as a whole.
Reflex Chaining:• A stimulus leads to a response, which becomes the
stimulus for the next response, which becomes the stimulus for the next response.
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Stimulus Response Response
Clinical Implications of Reflex Theory
If chained or compounded reflexes are the basis for the functional movement, clinical strategies designed to test reflexes should allow therapists to predict function.
Patient’s movement behaviors would be interpreted in terms of presence or absence of controlling reflexes.
Retraining motor control for functional skills would focus on enhancing or reducing the effect of various reflexes during motor tasks.
Motor Control
Limitations of Reflex Theory
Reflex must be activated by an outside agent, theory cannot explain voluntary or spontaneous movement.
Cannot explain movement that occurs in the absence of a sensory stimulus.
Cannot explain movements that occur too rapidly. Fails to explain that a single stimulus can result in
varying responses depending on context and descending commands.
Does not explain the ability to produce novel movements.
Motor Control
Ecological Theory
James Gibson (1966 - Psychologist) How motor systems allow us to interact
most effectively with the environment to perform goal-directed behavior
Motor Control evolved so that animals could cope with the environment around them, moving in it effectively to find food, run away from predators, build shelter, and even play.
Motor Control
Ecological Theory
Actions require perceptual information that is specific to desired goal-directed action performed within a specific environment.
The organization of action is specific to the task and the environment in which the task is being performed.
Motor Control
Ecological Theory
Perception focuses on detecting information in the environment that will support the actions necessary to achieve the goal.
From ecological perspective, it is important to determine how an organism detects information in the environment that is relevant to action, what form this information takes, and how this information is used to modify and control movement.
Motor Control
Clinical Implications Ecological Theory
Describes individual as an active explorer of the environment which allows individual to develop multiple ways to accomplish a task.
This may help patients to explore more and find different options to execute particular task and then analyze the most suitable and efficient way.
Motor Control
Limitations of Ecological Theory
Inability of the theory to explain the organization and function of the nervous system, which led to this interaction between the individual and the environment.
Motor Control
Hierarchical Theory
Hughlings Jackson (Physician)
• Organizational control which is TOP DOWN
• The Nervous System is controlled so that the higher centers control and influence lower centers on a strictly hierarchical basis.
Motor Control
Hierarchical Theory
Rudolf Magnus• Reflexes are part of hierarchy of motor control, in
which higher centers inhibit these lower reflex centers.
Georg Schaltenbrand• Described development of mobility in terms of
appearance and disappearance of a progression of hierarchically organized reflexes.
• Pathology of brain may result in persistence of primitive lower level reflexes.
• Understanding of reflexes would allow, determination of neural age of a child or a patient with motor control dysfunction.
Motor Control
Hierarchical Theory
Stephan Weisz Hierarchically organized reflex reactions
(basis for equilibrium in humans) Explained the relationship between the
maturation of equilibrium reflexes and the child’s ability to sit, stand and walk.
Motor Control
Hierarchical Theory
Arnold Gesell & Myrtle McGraw Neuromaturational Theory
Attributes normal motor development to increasing corticalization of the CNS
Assumes that CNS maturation is the primary agent for the change in development.
Motor Control
Hierarchical Theory
Example: Reaching The component parts of the stored movement
program in the brain are activated; These exert either a facilitatory or inhibitory
influence on spinal neurons & interneuron's via corticospinal pathways
Neuromuscular activity is initiated to complete the task
Once the movement has been learnt it can be performed without the need for peripheral feedback.
Motor Control
Clinical Implication of Hierarchical Theory
Reflex assessment profiles are used to estimate the level of neural maturation and predict functional ability.
• When influence of higher centres is temporarily or permanently interfered with, normal reflexes become exaggerated and so called pathological reflexes appear. (Brunnstrom)
• Release of motor responses integrated at lower levels from restraining influences of higher centres, especially that of the cortex, leads to abnormal postural reflex activity. (Bobath)
Motor Control
Limitation of Hierarchical Theory
Cannot explain dominance of reflex behavior in certain situations in adults. Eg: Stepping on pins results in immediate
withdrawal of the leg. Reflex within the lowest level of the hierarchy
dominating motor function. (BOTTOM UP CONTROL)
All low-level behaviors are primitive, immature and non-adaptive.
Higher level (cortical) behaviors are mature, adaptive and appropriate.
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Motor Programming Theories
Wilson, Grillner, Taub Can have patterned motor response with
or without sensory stimulus Explanation based on Physiology of
Actions rather than Physiology of Reactions
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Motor Programming Theories
Experimental Evidences in support for these theories Grasshopper or Locust experiment
• Wing beat in flight depended on rhythmic pattern generator
• Absence of sensory nerves – nervous system by itself generated the movements but were slowed
• Hence, sensory inputs are not essential in driving the movements but has important function in modulating the actions.
Motor Control
Motor Programming Theories
Experimental Evidences in support for these theories Locomotion in cats experiment
• Without sensory inputs or descending patterns from brain also rhythmic locomotor actions can be produced by the spinal neural networks
• Reflexes do not drive the action, but the central pattern generators (spinally mediated motor programs) by themselves can generate complex movements.
Motor Control
Motor Programming Theories
Motor Program – two meanings Central pattern generator (CPG)- specific
neural circuit in spinal cord– Neural networks that can endogenously (i.e. without
rhythmic sensory or central input) produce rhythmic patterned outputs or as neural circuits that generate periodic motor commands for rhythmic movements such as locomotion
Motor program – stored rules for generating movements so that we can perform the tasks with a variety of effector systems; prestructured set of motor commands
Motor Control
Motor Programming Theories Central pattern generator (CPG)
• To be classified as a rhythmic generator, a CPG requires: – Two or more processes that interact such that each process sequentially
increases and decreases– As a result of this interaction, the system repeatedly returns to its starting
condition.
• Three roles of modulation have been found for CPG circuits:– Modulation in CPG as Part of Normal Activity – Modulation Changes the Functional Configuration of CPGs to Produce
Different Motor Outputs
– Modulation Alters CPG Neuron Complement by Switching Neurons Between Networks and Fusing Formerly Separate Networks into Larger
Entities • Functions in vertebrate animals:
– Movement– Breathing– Rhythm Generation and other Oscillatory Functions
Motor Control
Motor Programming Theories
Central Pattern Generator (CPG) Grillner, 1975 - inherited system for patterned
movements – e.g. locomotion, chewing– Initiated by a triggering stimulus – Centrally organized – No need for sensory input – Primarily dealing with alternating repetitive movements
Central pattern generator (CPG) vs. motor program:
– CPG = genetically predetermined activities – Motor program = learned activities
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Clinical Implications of Motor Programming Theories
If higher levels of motor programming are not affected, can use alternate effectors.
If cortex is damaged, you have to re-teach the rules. Intervention should focus on retraining
movements important to a functional task, not just on reeducating specific muscles in isolation
Motor Control
Limitations of Motor Programming Theories
CPG- expansion of knowledge of flexibility of the nervous system in creating movements, does not explain sensory input importance
Motor program concept does not take into account musculoskeletal system and environmental variables.
Motor Control
Systems Theory
Nicolai Bernstein (Russian Scientist) Output of Nervous System as filtered
through a mechanical system, the body.• Taken into account different factors like, mass,
forces such as gravity and internal forces including both inertial & Movement-dependent forces.
Same central commands could result in quite different movements because of the interplay between external forces and variations in the initial conditions.
Motor Control
Systems Theory
Control of integrated movement is probably distributed throughout many interacting systems working cooperatively to achieve movement. (Distributed Model of Motor Control)
Coordination of movement is a process of mastering the redundant degrees of freedom.
Motor Control
Clinical Implications of Systems Theory
Need to assess CNS deficits as well as
Musculoskeletal System Examination and intervention must focus
not only on the impairments within individual systems contributing to motor control, but the effect of interacting impairments among multiple systems.
Motor Control
Limitations of Systems Theory
Systems theory does not focus on the interaction of the organism with the environment.
Difficult to relate theoretical components to neuro-anatomy.
Model is abstract.
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Information Processing Theory
Information processing theorists proposed that like the computer, the human mind is a system that processes information through the application of logical rules and strategies.
Like the computer, the mind has a limited capacity for the amount and nature of the information it can process.
Motor Control
Information Processing Theory
Computer can be made into a better information processor by changes
• in its hardware (e.g., circuit boards and microchips) • its software (programming)
Humans become more sophisticated thinkers through changes
• in their brains and sensory systems (hardware) • in the rules and strategies (software) that they
learn.
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Information Processing Theory
Sensory Register Capacity
• Very large
Duration• 0.5 to 3 seconds
Contents• Information perceived by the sensory receptors
(encoded as perceived)
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Information Processing Theory
Sensory Register & its Control Processes Recognition
• Noting key features of a stimulus and relating them to already stored information
Attention• Selective focusing on a portion of the information
currently stored in the sensory register
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Information Processing Theory
Short Term Memory Capacity
• 7 +/- 2 chunks of information
Duration• 20 to 30 seconds
Contents• What you are currently thinking about (information
from the sensory register and information from long term memory)
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Information Processing Theory
Short Term Memory & its Control Processes Rehearsal
• Maintenance rehearsal – Repeating information over and over again; no effect on
long-term memory storage
• Elaborative rehearsal– Relating new information to knowledge already stored in
long-term memory
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Information Processing Theory
Long Term Memory Capacity
• Unlimited
Duration• Permanent, long-term
Contents• Schemata
– In general is a specific, well-documented, and consistent plan.
– In psychology and cognitive science, is a mental structure that represents some aspect of the world.
– People use schemata to organize current knowledge and provide a framework for future understanding.
Motor Control
SENSORY
REGISTERS
SENSORY
REGISTERS
Info
rmati
on /
Data
eyes, ears, nose, mouth, skin
Information Processing TheoryMotor Control
SENSORY
REGISTERS
SENSORY
REGISTERS
Short-term store
Infinite data are briefly maintained (0.5 – 3.0
seconds) for preliminary analysis.
some info is selected for short term
memory
Info
rmati
on /
Data
Information Processing TheoryMotor Control
SENSORY
REGISTERS
SENSORY
REGISTERS
Short-term store
Infinite data are briefly maintained (0.5 – 2.0
seconds) for preliminary analysis.
Short-term (working) memory
(A limited amount of data is maintained
for approximately 20 seconds.
some info is transferred to
working memory
Info
rmati
on /
Data
Information Processing TheoryMotor Control
SENSORY
REGISTERS
SENSORY
REGISTERS
Short-term store
Infinite data are briefly maintained (0.5 – 2.0
seconds) for preliminary analysis.
Short-term (working) memory
(A limited amount of data is maintained
for approximately 20 seconds.
Long-Term memory.
Transformed or coded data
become part of the knowledge
system.
even less passes on to long term memory to storage
Info
rmati
on /
Data
Information Processing TheoryMotor Control
Data lost from the system Data lost from the system
SENSORY
REGISTERS
SENSORY
REGISTERS
Short-term store
Infinite data are briefly maintained (0.5 – 2.0
seconds) for preliminary analysis.
Short-term (working) memory
(A limited amount of data is maintained
for approximately 20 seconds.
Long-Term memory.
Transformed or coded data
become part of the knowledge
system.
some info is lost
Info
rmati
on /
Data
Information Processing TheoryMotor Control
EXECUTIVE CONTROL PROCESSESEXECUTIVE CONTROL PROCESSES
Data lost from the system Data lost from the system
SENSORY
REGISTERS
SENSORY
REGISTERS
Short-term store
Infinite data are briefly maintained (0.5 – 2.0
seconds) for preliminary analysis.
Short-term (working) memory
(A limited amount of data is maintained
for approximately 20 seconds.
Long-Term memory.
Transformed or coded data
become part of the knowledge
system.
metacognitive processes control the whole process
Info
rmati
on /
Data
Information Processing TheoryMotor Control