Theories of Motor Control
Assumptions
Clinical Implications
Limitations
Reflex Theory
- Sherrington
- “Peripheralist”
- Reflexes are basis for all mvmt
- External stimulus leads to mvmt
- Nervous System – triggers, coordinates, &
activates muscles
- Use sensory input to control motor output
- Stimulate good reflexes
- Inhibit undesirable (primitive) reflexes
- Relies heavily on feedback
- Reflex can’t be basic unit of behavior
- Doesn’t explain fast mvmts
- Doesn’t explain how single stimulus results
in varying responses.
- Doesn’t explain voluntary mvmts.
Hierarchical Theory
- JH Jackson
- “Centralist”
- “Top-Down” unidirectional flow
- Voluntary mvmts initiated by “will” (higher
levels)
- Reflexive mvmts dominate only after CNS
damage.
- Bernstein
- Goal-directed behavior (Task Oriented)
- Synergies to master redundant degrees of
freedom
- Feedback (closed loop)
- Identify & prevent primitive reflexes
- Reduce hyperactive stretch
- Normalize tone
- Facilitate “normal” mvmt patterns
- DEVELOPMENTAL SEQUENCE
- Recapitulation
- Doesn’t explain dominance of reflexive
behaviors in normal adults
- Everyone’s developmental pattern is diff.
- Hands-on approach  pt may become very
passive
- Identifiable, functional tasks
- Practice under a variety of conditions
- Modify environmental contexts
- Very broad – many diff. systems
- Doesn’t focus as heavily on the interaction of
the organism w/ the environment.
- Central Motor Pattern – motor response w/o
sensory stimulus/reflex
- Central pattern generators (CPGs) – spinal motor
programs that can produce mvmt w/o cortical or
sensory input
- Higher-level motor programs – store rules for
generating mvmts.
- New mvmt emerges 2o to change in control
parameter.
- De-emphasize commands from CNS in
controlling mvmt and emphasize physical
explanations for mvmt
- Attractor state – preferred pattern (vice-versa)
- Deeper attractor well  more stable pattern
- Stable patterns become more variable prior to
transition to new mvmt pattern.
- James Gibson
- Perception-action system
- Perception focuses on detecting information in
the environment that will support the actions
necessary to achieve the goal.
- Abnormal mvmt – not just reflexive, also
including abnormalities in central pattern
generators or higher level motor programs.
- Help pts relearn the correct rules for action
- Retrain mvmts important to fxn’al task
- Do not just reeducate muscles in isolation
- Not intended to replace importance of
sensory input in controlling mvmt
- Central motor program can’t be sole
determinant of action
- Doesn’t explain nervous sys. dealing w/ both
musculoskeletal & environment variables
- Mvmt is an emergent property from the
interaction of multiple elements.
- Understand the physical & dynamic properties
of the body
- i.e.) Velocity- important for dynamics of
mvmt. May be good to encourage faster mvmt
in pts to produce momentum and therefore help
weak pts move w/ greater ease.
- Nervous sys. has unimportant role
- Presumption that the relationship b/w the
physical sys. & environment determines
behavior.
- Help pt explore multiple ways in achieving
fxn’al task  discovering best solution for pt,
given the set of limitations
-
- Gives less emphasis on nervous sys.
Systems Theory
Motor Programming
Theory
Dynamical Action
Theory
Ecological Theory