Enquiry 4, Motor Control Theories Flashcards
What is motor control?
- Motor control is defined as the ability to regulate or direct the mechanisms essential to movement.
- Therapeutic intervention is often directed at changing movement or increasing the capacity to move.
- Therapeutic strategies are designed to improve quality and quantity of posture and movements essential to function.
What are the factors within the individual that constrain movement?
What makes up the nature of movement?
what are the task constraints on movement?
what are the environmental constraints on movement?
Explain the reflex theory? Include limitations and clinical implications
Limitations:
- The reflex can not be considered the basic unit of behavior.
- The reflex theory does not adequately explain and predict movement that occurs in the absence of a sensory stimulus.
- The theory does not explain fast movements.
- The concept that a chain of reflexes can create complex behaviors fails to explain the fact that a single stimulus can result in varying responses depending on context and descending commands.
- It does not explain the ability to produce novel movements.
Clinical Implications:
- If chained or compounded reflexes are the basis for functional movement, clinical strategies designed to test reflexes should allow therapist to predict function.
- A patient’s movement behavior 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.
Explain the Hierarchical theory? Include limitations and clinical implications
- The nervous system is organized as an hierarchy.
- Hierarchical control is defined as organizational control that is top down.
- The current concept describing hierarchical control within the nervous system recognize the fact that each level of nervous system can act on other level depending on the task.
Limitations:
- It can not explain the dominance of reflex behavior in certain situations in normal adults. E.g. stepping on a pin.
Clinical Implications:
- Abnormalities of reflex organization have been used by many clinicians to explain disordered motor control in the patient with a neurologic disorder.
- The reflex hierarchical theory was used to describe disordered movement following a motor cortex lession.
- Bobath sated that “ the release of motor responses integrated at lower levels of from restraining influences of higher centers, especially that of the cortex, leads to abnormal postural reflex activity. ”
Explain the Motor programming theory? Include limitations and clinical implications
- The concept of a central motor pattern, or motor program, is more flexible than the concept of a reflex.
- As it can either be activated by sensory stimuli or by central processes.
- The term motor program may be used to identify a central pattern generator, that is a specific neural circuit.
Limitations:
- The motor program cannot be considered to be the sole determinant of action.
- Thus the motor program concept does not take into account the fact that the nervous system must deal with both musculoskeletal and environmental variables in achieving movement control.
Clinical Implications:
- Explanations for abnormal movement have been expanded to include problems resulting from abnormalities in central pattern generators or in higher levels of motor programs.
- In patients whose higher level of motor programming are affected, motor program theory suggest the importance of helping patients relearn the correct rule for action.
Explain the Systems theory? Include limitations and clinical implications
- Berstein , a Russian scientist, was looking at the nervous system and body in a whole new way.
- He suggested that one can not understand neural control of movement without an understanding of the characteristics of the system you are moving and the external and internal forces acting on the body.
- In describing the body as a mechanical system, berstein noted that we had many degrees of freedom that need to be controlled.
- As a solution to the degree of freedom problem, he hypothesized that hierarchical control exists to simplify the control of the bodies multiply degrees of freedom.
- He believed that synergies play an important role in solving the degree of freedom problem.
Limitations:
- It does not focus heavily on the interaction of the organism with the environment, as do some other theories of motor control.
Clinical Implications:
- It stresses the importance of understanding the body as a mechanical system.
- When working with a patient who has CNS deficit, the the therapist must be careful to examine the contribution of impairments in the musculoskeletal system, as well as the neural system, to overall loss of motor control.
Explain the Ecological theory? Include limitations and clinical implications
- The ability to use perceptions to guide action emerges early in life.
- Gibson, stated that perception focuses on detecting in the information in the environment that will support the action necessary to achieve the goal.
- The ecological perspective has broadened our understanding of nervous system function from that of a sensory/motor system, reacting to environmental variables, to that of perception/action system that actively explores the environment to satisfy its own goals.
Limitations:
- It has tended to give less emphasis to the organization and function of the nervous system that led to this interaction.
Clinical Implications:
- A major contribution of this view is in describing the individual as an active explorer of the environment.
- An important part of intervention is helping the patient explore the possibilities for achieving a functional task in multiple ways.
- The ability to develop multiple adaptive solutions to accomplish a task and discover the best solution for them, given the patients set of limitations.
Explain the Dynamical Action theory? Include limitations and clinical implications
- Self organization is a fundamental dynamic systems principle.
- It says that when a system of individual parts come together, its elements behave collectively in an ordered way. There is no need for a higher center issuing commands in order to achieve coordinated action.
- This principle applied to motor control predicts that movement could emerge as a result of interacting elements, without the need for specific command or motor programs within the nervous system.
- This theory suggests that the new movement emerges due to a critical change in one of the systems called a control parameter.
- A control parameter is a variable that regulates change in the behavior of the entire system.
- An important concept in describing movement from a dynamic action theory perspective is that of attractor state.
- Attractor states may be considered preferred patterns of movement used to accomplish common activities of daily life.
Limitations:
- The presumption that the nervous system has a fairly unimportant role and that the relationship between the physical system of the animal and the environment in which it operates primarily determines the animal’s behavior.
Clinical Implications:
- Movement is an emergent property.
- i.e it emerges from the interaction of multiple elements that self organize based on certain dynamic properties of the elements themselves.
- It means that alterations in the movement behavior can be explained in terms of physical principles rather than necessarily in terms of neural structures.
What is the integrated theory?
- Integrated motor-control theory that reflects key elements of hierarchical, systems, dynamic action, and ecological theories.
- This integrated systems-based theory conceptualizes (develop the thought of) movement as a product of the interaction among the individual, the task, and the environment.
- Shumway-Cook and Woollacott’s theory reflects many of the concepts of other systems-based theories, in which movement is thought to be generated by an individual to meet the demands of a specific task performed within a specific environment.
- Which is the most complete theory of motor control the one that really predicts the nature and cause of movement? which is consistent with our current knwoledge of brain anatomy and physiology. No one theory has it all, all theories can help to explain types of movement or elements of movement control but each theory also has its limitations (as seen in other cards).
- So when looking at the best theory of motor control, it has to be one that combines elements from all of the theories presented so a comprehensive or integrated theory that recognises the elements of motor control we do know about but also leaves room for things we dont know so much about. Any current theory of motor control basically unfinished becquse as a science were learning and adding to our knowledge base constantly.
What is the nature of movement?
Movement:
Emergent phenomena from the interaction of individual, task & environment
What are the indivdidual constraints on movement?
Movement requires interaction between processes of perception, cognition and action
Perception:
Of the task, environment and our body
Cognition:
To understand what we have perceived and process it into an appropriate motor plan
Action:
Ability to communicate that plan to muscles and put it into action
What are the task constraints on movement?
Tasks can be analysed according to the specific attributes that are inherent in the task:
●Discrete, continuous, serial -
Discrete - kicking a ball/sitting to standing, have a clear beginning and end
Continous - walking or running, the end point of the task is descided arbitrarily (randomly) by the individual performing the task
Serial/Continuous - a series of routines that is continued over a period of time
●Stability vs mobility -
Stability - sitting or standing are performed with a non moving base of support
Mobility - walking or running, require moving the base of support of the individual.
Manipulation continuum -
Tasks requiring manipulation using upper extremeties
●Attention continuum -
Looks at the amount of attentional demand for a given task
●Open vs closed -
compare open movements, such as playing football or tennis, which require performers to adapt movement stratedgies to a constantly changing and unpredictable environment vs closed movement tasks, performed in a fixed or predictable environment. (closed chain - foot fixed on the ground)
