Occupational therapy and application of Motor Control Part 1

This article will involve three parts ,for the convenience of readers and better conceptual understanding i am simplifying by starting with the basic understanding of motor control and motor learning and this will be a revision of theory ,subsequent parts will focus on description of its application and recent research work.

What is Motor Control?

-An ability to regulate and direct the mechanisms essential to movement.
The process of initiating, directing, and grading purposeful voluntary movement".

So lets address  how CNS organizes many individual muscles and joints in to coordinated functional pattern? or
How sensory information from body and environment is used to select and control movement?

Physical and Occupational therapists have been referred to as "Applied Motor Control Physiologist"(Brooks 1986) -because we spend considerable amount of time in understanding Motor control problems and as an occupational therapist our therapeutic strategies is directed in improving and retraining the functional movements & patterns.

The organization and production of movement is a complex problem, so the study of motor control has been approached from a wide range of disciplines, including psychology, cognitive science, bio-mechanics and neuroscience.

The control of human movement has been described in many different ways with many different models of Motor Control put forward throughout the 19th & 20th Centuries. Motor Control Theories include production of reflexive, automatic, adaptive, and voluntary movements and the performance of efficient, coordinated, goal-directed movement patterns which involve multiple body systems (input, output, and central processing) and multiple levels within the nervous system

We will be understanding this in detail:

Let us focus on understanding of Movement:
its interaction of movement ,task and the environment

So organization of movement is constrained by factors

• Within Individual
•  the task
• and environment

Within Individual factors that constrain Movement:

Movement and Action
 Movement and Perception
Movement  and Cognition

Task Constraints on Movement

Environmental constraints on Movement

Theories of Motor Control:

Readers can refer to Motor Control, Ann Shumway-Cook  for detailed description:

MOTOR CONTROL THEORIES	AUTHOR	DATE	PREMISE	CLINICAL IMPLICATIONS
Reflex Theory	Sherrington	1906	Movement is controlled by stimulus-response.  Reflexes are basis for movement - Reflexes are combined into actions that create behavior.	Use sensory input to control motor output  Stimulate good reflexes  Inhibit undesirable (primitive) reflexes  Rely heavily on Feedback
Dynamical Systems Theory	Bernstein  Turvey  Kelso & Tuller  Thelen	1967  1977  1984  1987	Movement emerges to control degrees of freedom.  Patterns of movements self-organize within the characteristics of environmental conditions and the existing body systems of the individual.  Functional synergies are developed naturally through practice and experience and help solve the problem of coordinating multiple muscles and joint movements at once.  De-emphasize commands from CNS in controlling movement and emphasize physical explanations for movement.	Movement is an emergent property from the interaction of multiple elements.  Understand the physical & dynamic properties of the body - i.e. Velocity- important for dynamics of movement. May be good to encourage faster movement in patients to produce momentum and therefore help weak patients move with greater ease.
Hierarchical Theories	Adams	1971	Cortical centers control movement in a top-down manner throughout the nervous system.  Closed-loop Mode: Sensory feedback is needed and used to control the movement.  Voluntary movements initiated by “Will” (higher levels). Reflexive movements dominate only after CNS damage.	Identify & prevent primitive reflexes  Reduce hyperactive stretch  Normalize tone  Facilitate “normal” movement patterns  Developmental Sequence  Recapitulation
Motor Program Theory	Schmidt	1976	Adaptive, exible motor programs (MPs) and generalized motor programs (GMPs) exist to control actions that have common characteristics.  Higher-level Motor Programs - Store rules for generating movements.	Abnormal Movement - Not just reflexive, also including abnormalities in central pattern generators or higher level motor programs.  Help patients relearn the correct rules for action  Retrain movements important to functional task  Do not just reeducate muscles in isolation
Ecological Theories	Gibson & Pick	2000	The person, the task, and the environment interact to in uence motor behavior and learning. The interaction of the person with any given environment provides perceptual information used to control movement.  The motivation to solve problems to accomplish a desired movement task goal facilitates learning.	Help patient explore multiple ways in achieving functional task → Discovering best solution for patient, given the set of limitations
Systems Model	Shumway-Cook	2007	Multiple body systems overlap to activate synergies for the production of movements that are organized around functional goals.  Considers interaction of the person with the environment.  Goal-directed Behavior - Task Orientated	Identifiable, functional tasks  Practice under a variety of conditions  Modify environmental contexts

Let's move to concept of Motor Learning

Motor learning is when complex processes in the brain occur in response to practice or experience of a certain skill resulting in changes in the central nervous system that allow for production of a new motor skill.

So ,Motor Control focuses on  understanding of movement already acquired

Motor learning focuses on understanding the acquisition or modification of movement.

• Motor learning research often considers variables that contribute to motor program formation (i.e., underlying skilled motor behaviour), sensitivity of error-detection processes, and strength of movement schemas. There are many different theories of Motor Learning
• Reference:Roller L et al, Contemporary Issues and Theories of Motor Control, Motor Learning, and Neuroplasticity. In: Neurological Rehabilitation 6th Edition. Mosby, 2012. p69 - 105.

Stages of Motor Learning

Stages of Learning	Characteristics	Attention Demands	Activities	Description
Cognitive	Movements are slow, inconsistent and inefficient. Considerable cognitive activity is required.	Attention to understand what must move to produce a specific result. Large parts of the movement are controlled consciously	Practise sessions are: performance focused less variable incorporate a clear mental image (technical & visual).	Early Cognitive; Essential Elements were not observed or not present
				Late Cognitive; Essential elements are starting to appear
Associative	Movements are more fluid, reliable and efficient Less cognitive activity is required	Some parts of the movements are controlled consciously, some automatically.	Practise sessions link performance and results, conditions can be varied. Clear Mental Image = Accurate Performance	Early Associative; Essential elements appear, but not with consistency.
				Late Associative; Essential elements appear regulalry at a satisfactory level.
Autonomous	Movements are accurate, consistent and efficient. Little or no cognitive activity is required.	Movement is largely controlled automatically Attention can be focused on tactical choices	Practise sessions are more results orientated Focus is on greater range of movement, speed, acceleration and use of skill in a novel situation.	Early Autonomous; Essential elements appear frequently avove required level.
				Late Autonomous; Essential elements appear continuously at a superior level.

 There are many different theories of Motor Learning. 

MOTOR LEARNING THEORY	AUTHOR	DATE	PREMISE	CLINICAL IMPLICATIONS
Adams Closed Loop Theory	Adams	1971	Closed Loop - Sensory feedback is used for the ongoing production of skilled movement  Slow movements  Relies on sensory feedback (Sherrington)  Blocked Practice  Errors = Bad! Needs to be accurate!  Memory Trace - Initiation of movement  Perceptual Trace - Built up over a period of practice & is the reference of correctness.   Improvements = Increased capability of performer to use the reference in closed loop	Perform same exact movement repeatedly to one accurate end point  Increase Practice → Increase Learning  Errors produced during learning → Increase strength of incorrect perceptual trace
Schmidt's Schema Theory	Schmidt	1975	Open Loop  Schema - Abstract memory representation for events → RULE  Generalized Motor Program - Rules that allow for the generation of novel movements  Rapid, ballistic movements = recall memory withmotor programs and parameters to carry out movement without peripheral feedback  Variability of Practice → Improve Motor Learning	Optimal Learning → Task practiced under many different conditions  Positive benefits for error production (learn from own mistakes)  Schema has rules for all stored elements, not just correct elements
Ecological Theory	Newell	1991	Based on Systems & Ecological Motor Control Theories  Motor Learning = Increases coordination between perception and action thru task & environmental constraints.  Perceptual-motor workspace - Identifies movemets and perceptual cues most relevant to performance of task  Optimal task-relevant mapping of perception & action → NO Rules!	Patient learns to distinguish relevant perceptual cues important to action.

Theories Related to Stages of learning Motor Skills:

1) Fitts and posner Three Stage Model:(1967)

They suggest there are three main phases involved in skill learning

First stage:

Learner is focused on understanding the nature of task and developing strategies for the same.

Requires high degree of cognitive activity so referred as cognitive stage of learning.

Eg: first day of driving lesson of Mr Ben would require high degree of attention and consious thought

may make a lot of errors in gear shift and ABC control of manual car.

Second stage:

 By this time person has selected best strategy for task and now begins to refine the skill

less variability in performance ,improvement occurs slowly

Referred as Associative stage of learning

Here,verbal/cognitive component not important as focus is on refining a particular pattern than focusing on alternative strategies.

eg: Mr Ben is learning to shuffle from second to third and then first gear as per the speed of vehicle while simultaneously applying ABC control.He is refining on his learned skills

Third stage:

Autonomous stage-there is automacity of skill and involves low degree of attention

Eg: Mr Ben can now enjoy a long drive with friends enjoying on the laughter,talks and the beautiful climate outside.

2)Systems Three Stage model:

Bernstein 1967

3 stages (novice, advanced, expert) theory of motor learning that accounts for reductions in body degrees of freedom seen in child development and new skill acquisition in general. 

The novice stage involves the learner freezing degrees of freedom by co-contracting agonists and antagonists to constrain a joint to simplify the movement, as with the rigid bracing of the wrist when first learning to use a hammer. 

Degrees of freedom are progressively released through the advanced and expert stages enabling movement at more joints and more sophisticated muscle synergies across multiple joints until smooth, coordinated movements are performed. 

3)Gentile two stage Model

1972,1987

this theory of motor skill acquisition describes the goal of learner in each stage.

First stage :involves understanding the goal of the task,developing movement strategies appropriate to achieving goal and understanding environmental features critical to organization the movement.

 -distinguishes relevant/regulatory features from non regulatory

 Second is fixation/diversification stage,goal is to refine the movement.

References:

Ann Shumway Cook,Motor control 4th edition

Science Direct

Physiopedia

In the Next articles i will be discussing on skills and abilities and therapeutic application.

-SSW