Motor Control Theories

• Theory is a scientifically acceptable principle or a body of principles that explain phenomena, or a belief/policy/procedure that serves as the basis for action.
• Theory is critical for physical and occupational therapists, as they are considered applied motor control physiologists.
• It serves as a framework for interpreting behavior and provides a guide for clinical interventions.
• Theory allows for the generation of "New ideas” for interventions and gives a working hypothesis for examination and intervention.

Understanding Movement

• Movement production (motor control) and acquisition (motor learning) can be achieved from having a theory
• Motor Control is formally defined as the ability to regulate or direct the mechanisms to essential to movement.

Motor Control Theories

• There are several types of motor control theories including: information processing models, functional actions, systems theory, and ecological theory.
• Information Processing Models: movements are produced based on the flow of sensory information.
• Reflex Theory (Sherrington, 1947): Movement is organized around reflexes.
• Hierarchal Models (e.g., Hughlings Jackson): The nervous system is hierarchically organized.
• Motor Program Theories: capable of carrying out movements without the use of feedback.
• Motor program theory (Bernstein, 1967; Keele, 1968; Wilson, 1961).
• Schmidt's schema theory (1975)
• Functional actions are viewed broadly as emerging from the relationship between the organism and the environment
• Systems Theory (Nicolai Bernstein, 1967), also known as the dynamic systems or action systems theory, says that movements emerge.
• Ecological Theory (James Gibson, 1966): similar to systems theory, but the focus is more on the perceptual interface between the individual and environment.

Information Processing Models

• Information processing models suggest that movements are produced based on the flow of sensory information.
• Reflex Theory (Sherrington): Movement is produced by a “chain” of reflexes

Limitations of Reflex Theory

• Requires external stimulus to produce movement
• It cannot explain movements that occur faster than the reflex arc (10-30 milliseconds)
• A single stimulus can produce various responses
• New movements are not explainable
• Cannot explain goal-directed/proactive movements

Clinical Implications of Reflex Theory

• Focus on evaluating and treating reflexes

Hierarchal Models

• The brain's primary centers "rule" the lower structures in the CNS.
• Movements exist in the higher centers as represented this guides movement
• The flow of information is unidirectional, although this is a very simplistic definition
• Newer insights allow for less of a strict hierarchy
• Reflexes can dominate in instances for healthy adults
• Clinical Implications are Signe Brunnstrom and Bertha Bobath.

Motor Program Theories

• Stored programs can carry out movements without needing feedback.
• A "set of muscle commands that are structured before a movement sequence begins, and that allow the entire sequence to be carried out uninfluenced by peripheral feedback." (Keele)
• Evidence from deafferentation, response complexity, and limb-blocking studies supports the the theory.
• However there are limitations

Limitations of Motor Program Models

• Storage is needed for every movement (space limitation)
• Ignores sensory involvement
• Does not explain Novel movements
• Ignores biomechanics

Clinical Implications of Motor Program Models

• Abnormalities exist in CPG or higher-level motor program
• The clinical focus is on helping patients relearn the correct rules for action.
• Focus on retraining movements important to a functional task, and not just on re-educating specific muscles in isolation
• Variety is potentially not important

Schmidt's Schema Theory

• Developed to explain motor learning and contain elements of hierarchical theories.
• According to this theory the brain uses feedback from the movement that is compared with a generalized sensory representation to allow corrections and learning.
• Some movement parameters are invariant (unchanging), and others are variant (changing).
• This allows for motor equivalence

Limitations of Schmidt's Schema Theory

• Ignores biomechanics

Clinical Implications of Schmidt's Schema Theory

• Abnormalities occur in CPG or higher level motor program
• The clinical focus helping patients relearn the correct rules for action
• Focus on retraining movements important to a functional task, not just on re-educating specific muscles in isolation
• Variety is of importance
• It is not possible to learn from passive movement
• Schema theory predicts that learning requires active feedback processing, which requires attention.

Action Models

• Action Models suggest that functional actions are often viewed as emerging from the relationship between the organism and the environment.
• Systems/dynamic systems theory is more complicated and has 5 principle assumptions.
• It has evolved beyond the original Bernstein's original conceptualization around the degrees of freedom problem.
• The theory contains the following five assumptions:
• Self-organization: patterns of coordination emerge as a result of an interaction of subsystems of the movement (intrinsic (inside the individual) or extrinsic (movement and/or environment).
• Attractor states: preferred patterns of movement.
• Nonlinear: changes in behavior can be nonlinear or abrupt.
• Control parameters: movements patterns emerge as a result of changes in these.
• Order parameters: these are responsible for non-linear changes.

Limitations of Action Models

• The nervous system is deemphasized in preference to mathematical principles.

Clinical Implications of Action Models

• Consider the multiple systems that are involved.
• Consider the control parameters.
• View variability as necessary to increase the flexibility of movement.

Ecological Theory

• Has many of the elements of the systems approach.
• The ecological theory focuses moreso on how people use perception to extract the information necessary from the environment to produce an action.
• Motor control is a tool used to cope with the environment.

Limitations of Ecological Theory

• The nervous system is deemphasized in favor of the organism/environment interface

Clinical Implications of Ecological Theory

• Active exploration of the environment is important to develop multiple ways of achieving a task (adaptability).
• Patients need to learn to identify features in the environment that affect their movement (affordances).
• Features of the environment may need to be changed.

Task-Oriented Approach

• The approach used in this course is the Task-Oriented Approach
• Movement is emergent and results from the intersection of the individual, task, and environment.

Relevant Terms: Individual-Task-Environment Interactions

• Goal Directed Behavior:
• Includes both Investigatory Behaviors and Adaptive Behaviors
• Adaptive Behaviors include Functional Behaviors and Communicative Behaviors
• Levels of Analysis of Functional Behavior:
• Action: Change from initial to final state (performer environment interaction irrespective of how achieved)
• Movement: The way action goals are achieved
• Regulatory conditions: environmental features to which the movement must conform to achieve the action goal
• Neuromotor processes: Neural subsystems involved

The Individual

Multiple systems interact:

• Motor/Action System (neuromuscular & biomechanical systems)
• Sensory/Perceptual System
• Cognitive Systems

The Task

• A taxonomy is based on the environment in which movement takes place and on the functional role of the action.
• The task being performed influences the movement organization.
• Categories include: gross vs. fine motor, discrete/continuous/serial, closed vs. open (environmental context), stability/mobility (functional role), and manipulation/nanomanipulation (functional role)

The Environment

• Regulatory Elements: aspects of the environment that shape the movement through constant versus changing of regulatory elements between trials
• Nonregulatory Elements: may affect performance, but movement does not need to conform to these
• Types of environments: Stationary or Moving

Clinical Decision-Making and Motor Control Theories

• Clinical decision-making based on these theories involves: a framework of interpreting behavior and a guide of clinical action
• Clinical decision-making also requires working hypotheses for examination and intervention and incorporates new ideas.
• Motor control theory is never really finished because there is always room to integrate new information.
• Methods of assessing movement include observational analysis as well as functional assessment. TUG assessments, 2/6-minute walk tests, DGI assessment, and Functional Ambulation Classification are all examples of functional assessment. Temporal and spatial gait characteristics (GAITRite) can be used to assess gait
• Gait kinematics (Vicon) and kinetics (Vicon) can be used to assess gait deviations.
• EMG is another method.