Theories of motor control Flashcards
What are 4 characteristics of movement?
- Flexible
- Unique
- Some consistencies (gait)
- Adaptable
What is motor equivalence
Produce same movement outcome with a variety of different muscle groups
What is a motor control theory?
- Explanation of how the nervous system controls movement coordination and output
– Serves as a framework for clinical decision making
Reflex Theory
- Combined action of individual reflexes explained complex behavior
Drawbacks: Not flexible/adaptable movement; Doesn’t explain new movement or voluntary (internal) movement
Hierarchical Theory
- Higher centers are always in control and reflexes are ensted within organized levels of the CNS
- Higher neural center control lower neural centers; the higher you get the more complex.
We have all the capabilities in walking in the spinal cord but more complex walking requires higher up. Explains why babies have reflexes when young and grow out of them with the higher centers inhibiting the lower levels.
Drawback: Doesn’t take in to feedback control.
Motor Program Theory
- Motor Programming - command center in brain makes decisions on movement
– Motor program
— abstract representation of movement plan, stored in memory, contains all commands required to carry out intended action
– Early theories = 1 program for each movement
Drawback: Doesn’t take into account unique movements. Don’t have enough storage for every infinite movement possibility.
Generalized Motor Program (GMP)
A class of actions or patterns of movement that can be modified to yield various response outcomes.
Motor Program Theory
Components of GMP
Invariant features
– Relative sequence, timing, relative force
Parameters – flexible
– Overall duration - speed
– Overall force – amplitude or size of movement
– Movement direction
– Muscle selection
Explains discrete moevement very well as it has a start and stop
Example of GMP
Drawing signature with right hand, left hand and mouth
Execution of GMP
- Make decision to act
- Retrieve appropriate GMP from memory
- Add estimated parameter values to achieve the desired outcome in advance
- Send signal to move
Stand on mound, decide which pitcher, decide where to aim, send signal to throw
Drawback: Lacks feedback
What is open loop control?
- Short discrete movement
- Use feedback to update movement
- Ex: Shoot a basketball short, result in you shooting it farther next time
Closed Loop Control
Ex: Biking up a hill and want to keep same speed you have to up the force to continue going
Doing a movement and adapting to the feedback while performing it.
Clinical Implications of GMP Theory
- Examine underlying motor programs & processes
- Help patients relearn general rules for movement (focus is on normalizing movements)
- Recently increased consideration for functional tasks vs. isolated muscles
- Now everything must be functional because that is how we move! Not isolated muscles.
Systems Theory
- Movement isn’t nervous system itself but all the systems acting on each other. (sympathetic vs parasympathetic, etc.)
- CNS organized through synergies (coordinative structures); Neural organization has ways to simplify things.
What is a synergy
- Neural organization of multiple elements
What are the two types of synergies?
- Neural circuitry that organizes elements to share a task (stable)
– “synergistic firing”
– Ex. Flexor /extensor synergies
– Ex: Standing in place all of the muscles work together to keep you stable - Pattern of co-variation among the elements with the purpose to stabilize performance (flexible)
“Synergistic activities”
Ex. finger forces during gripping (adjusts to not allow it to slip)
Dynamics Systems Theory
- Skilled action emerges from dynamic interaction of numerous variables in body, environment and skill
- Movement isn’t governes by nervous sytem and that movement starts from all the systems together.
- Self-organization
– De-emphasizes the nervous system - Constraints
– Boundaries that influence movement capabilities
– Internal: state of body’s subsystems
– External: the task and the environment
Ex: Fingers on the table moving together go fast enough and it messes up but you tried to keep them together.
Dynamic System Theory - Attractor State
Stable movment pattern
Ex: Walking in the same pattern going 3mph, go up to 4.3 you destabilize the movement pattern, 5.5 run into comfortable run. The walk and run.
DST - Control Parameters
- When constraints change, stability of system is endangered
- If magnitude of change is enough, system will reorganize into a new form
- Control parameters = factors that regulate change in behavior
Significant constraint that has a large effect on movement pattern.
DSt - Movement variability
- Optimal window of variability
Purpose
- Important for exploration, distribution of tissue stress, and flexibility to adapt to an ever changing environment
- Consequences of lack of movement variability
- Too much performance can’t be perdicted, tissue are overworked.
- Too little can’t adapt to performance and tissues don’t adapt
DST - Clinical Implications
- Skill acquisition results from ongoing search for functional movement pattern that will accomplish a task goal
- Clinician must structure practice to facilitate exploration of different functional tasks/environments
Task Oriented Approach
- Normal movement emerges as an interaction of multiple systems
- Movement organized around a behavioral goal and is constrained by the environment
All motor control theories are ____ , some are useful
wrong
