Theories of motor control

Question 1

What are 4 characteristics of movement?

Answer 1

• Flexible
• Unique
• Some consistencies (gait)
• Adaptable

Question 2

What is motor equivalence

Answer 2

Produce same movement outcome with a variety of different muscle groups

Question 3

What is a motor control theory?

Answer 3

• Explanation of how the nervous system controls movement coordination and output
  – Serves as a framework for clinical decision making

Question 4

Reflex Theory

Answer 4

• Combined action of individual reflexes explained complex behavior

Drawbacks: Not flexible/adaptable movement; Doesn’t explain new movement or voluntary (internal) movement

Question 5

Hierarchical Theory

Answer 5

• 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.

Question 6

Motor Program Theory

Answer 6

• 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.

Question 7

Generalized Motor Program (GMP)

Answer 7

A class of actions or patterns of movement that can be modified to yield various response outcomes.

Motor Program Theory

Question 8

Components of GMP

Answer 8

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

Question 9

Example of GMP

Answer 9

Drawing signature with right hand, left hand and mouth

Question 10

Execution of GMP

Answer 10

1. Make decision to act
2. Retrieve appropriate GMP from memory
3. Add estimated parameter values to achieve the desired outcome in advance
4. Send signal to move

Stand on mound, decide which pitcher, decide where to aim, send signal to throw

Drawback: Lacks feedback

Question 11

What is open loop control?

Answer 11

• Short discrete movement
• Use feedback to update movement
• Ex: Shoot a basketball short, result in you shooting it farther next time

Question 12

Closed Loop Control

Answer 12

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.

Question 12

Clinical Implications of GMP Theory

Answer 12

• 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.

Question 13

Systems Theory

Answer 13

• 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.

Question 14

What is a synergy

Answer 14

• Neural organization of multiple elements

Question 15

What are the two types of synergies?

Answer 15

1. 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
2. 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)

Question 16

Dynamics Systems Theory

Answer 16

• 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.

Question 17

Dynamic System Theory - Attractor State

Answer 17

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.

Question 18

DST - Control Parameters

Answer 18

• 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.

Question 19

DSt - Movement variability

Answer 19

• 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

Question 20

DST - Clinical Implications

Answer 20

• 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

Question 21

Task Oriented Approach

Answer 21

• Normal movement emerges as an interaction of multiple systems
• Movement organized around a behavioral goal and is constrained by the environment

Question 22

All motor control theories are ____ , some are useful

Answer 22

wrong