Enquiry 4, Motor Control

Question 1

What is motor control?

Answer 1

The ability to regulate or direct the mechanisms essential to movement

Essential for all survival needs, walk, seek food, earn a living, communicate.

Question 2

What questions are addressed when thinking about motor control? (so what does motor control concern?)

Answer 2

• How the CNS orgainises the many individual muscles and joints into coordinated function
• How sensory info from the body and environment is used to select and control movement
• How we observe and analyse movement
• How we quantify and think about movement problems in our patients

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Question 3

How is understanding the nature and control of movement critical to clinical practice?

Answer 3

As Physios we spend considerable time:

●Retraining movement essential to function

●Increasing capacity for move

●Designing therapeutic strategies to improve the quality and quantity of movement

Question 4

What is the reason for motor control theories?

Answer 4

Describes view points regarding how movement is controlled.

Question 5

Why do we use and how are motor control theories part of the theoretical basis for clinical practise?

Answer 5

• Provide us with a framework for intepreting behaviour
• A guide for clinical action and reasoning
• Provide us with new ideas or different way of thinking
• They provide a working hypothesis for examination and intervention

Question 6

What are the theories of motor control?

Answer 6

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●Reflex Theory

●Hierarchical Theory

●Motor Programming Theory

●Systems Theory

●Dynamical Action Theory

●Ecological Theory

Question 7

Explain the reflex theory and its implications.

Answer 7

• Reflex chaining - believed that complex behaviour could be explained through the combined action of individual reflexes that are chained together.
• There has to be a sensory stimulus for every motor action.
• Movement is controlled by stimulus-response.

Implications:

• Use sensory input to control motor output

Stimulate good reflexes

Inhibit undesirable (primitive) reflexes

Rely heavily on Feedback

Question 8

Explain the hierarchical theory and its implications.

Answer 8

• Cortical centers control movement in a top-down orginational control throughout the nervous system.
• Closed-loop Mode: Sensory feedback is needed and used to control the movement.
• As the central nervous system matures in infancy (early childhood) higher levels gain control over lower levels
• Voluntary movementts initiated by “Will” (higher levels). Reflexive movements dominate only after CNS damage.

Implications:

• Identify & prevent primitive reflexes
• Reduce hyperactive stretch
• Normalize tone
• Facilitate “normal” movement patterns
• Developmental Sequence
• Recapitulation (repitition of evolutionary process)

Question 9

Explain motor programming theory and its implications:

Answer 9

An alternative way to view reflexes is to consider that one can remove a stimulus or afferent input but still have a patterned motor response. CNS physiology of actions rather than only reactions

Central motor pattern - if we remove the motor response from its stimulus we are left with this concept of a central motor pattern.

This concept is way more flexible than the concept of a reflex because it can be activated either by sesnory stimuli or central processes

Central pattern generator - specfic neural circuit

Implications:

• 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

Question 10

Explain the systems theory and its limitations.

Answer 10

• Same central command could result in different movements because of the interplay between external forces and variations in the initial conditions. So for the same reasons different commands could result in the same movement.
• Takes into account the contribution of the muscles, skeletal system, gravity and inertia along with the nervous system
• Control of integrated movement distributed throughout many interacting systems working cooperatively to achieve that movement
• Acknowledges we have many degrees-of-freedom that must be controlled

Degrees of freedom - we have many joints all of which flex, extend, rotate and this complicates movement control a lot. So bernstein said that coordination of movement is a process of mastering the redundant degrees of freedom of the moving organism - in other words, it involves converting the body into a controllable system