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. / - 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
Systems Theory / - Bernstein
- Goal-directed behavior (Task Oriented)
- Synergies to master redundant degrees of freedom
- Feedback (closed loop) / - 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.
Motor Programming Theory / - 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. / - 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
Dynamical Action Theory / - 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. / - 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.
Ecological Theory / - James Gibson
- Perception-action system
- Perception focuses on detecting information in the environment that will support the actions necessary to achieve the goal. / - 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.