what is motor control?
the ability to regulate or direct the mechanisms essential to movement
how does the individual impact movement?
- requires cooperative effort of many brain structures and processes
– sensory perception system: proprioception, environment, input from sensory systems
– cognitive: attention, motivation, planning, memory, problem solving
– motor system: muscles, joints, ROM, strength, tone, coordination, sequencing (NM and MS systems)
is reflex theory a stimulus or thought driven system?
stimulus driven, no conscious thought
- stimulus in –> response out
is reflex theory a top down or bottom up approach?
peripheral system dominant –> bottom up approach (distal to proximal)
how are complex movements explained with reflex theory?
combination of reflexes/reactions that were chained together (lower –> higher CNS development)
what are limitations to reflex model?
- what about voluntary movement
- a single stimulus can result in more than one response; we can override a reflex using higher brain centers (pulling a hand away from hot fire vs touching fire to save a child)
- doesn’t explain movement that occurs in absence of sensory stim
- what about fast and quick movements/movements that are too rapid to allow new sensory information to impact them (ex. fast typer)
- what bout new movements/applications of movement in new situations
is hierarchical theory a top down or bottom up approach?
top down, overlaps with reflex theory
- higher cortex motor association areas –> motor cortex –> spinal levels –> limbs move
according to hierarchical theory, what is the primary agent for change in development?
CNS maturation (reflexes decrease as we age and we use higher levels of the brain as we develop)
what does hierarchical theory say about damage to the CNS
results in a release of control by higher centers (release of inhibition) and results in spasticity or other movement dysfunction (and return of primitive reflexes), which causes movement disorders
what does hierarchical theory say about recovery of CNS dysfunction?
is a process of CNS regaining control (inhibition) over the lower centers
what does hierarchical theory say when the brain is damaged?
there will be an expression of lower-level reflexes
what are some examples of lower level reflexes?
patellar tendon, infant reflexes (moro, rooting, palmar grasp, etc), motor response: flexor withdrawal or extensor response, pupillary dilation/constriction, close eyes in response to something coming to your face
what is considered a higher level reflex?
- when the cortex impacts movement
- low level auditory startle vs movement to a command
- low level visual tracking vs object recognition
- low level flexor withdrawal to pain vs functional object use
- low level eyes opening with stimulation only vs maintaining attention
what are the limitations to hierarchal theory?
- does not explain dominance of reflex behavior in certain situations (flexor withdrawal - stepping on a pin results in immediate withdrawal of the leg; the lower level of the hierarchy dominates motor function)
- our response to the environment
- biomechanics factors not taken into account
what are some clinical implications of reflex and hierarchal theories?
- noting evolution of reflexes in pediatrics
- gait training based on limb position
- PNF
- interventions are aimed at gaining or regaining higher level reflexes and movements in a step wise approach
- tend to focus on resolving reflexes –> with limited evidence that this improves function
how does motor control theory suggest motor programs are activated?
- looks at both peripheral and central pieces to permit motor control
- a motor program can be activated by sensory input or central processes (a sensory input can alter a motor program)
what does motor control theory say about how typical movements are created?
synergy - typical movements are created by specific patterns
according to motor programming theory, what are central pattern generators (CPGs)?
- neural circuits that influence movement
- rhythmic input (quick stretch) can create a chain of events that permits walking, breathing, etc
how do central pattern generators function?
- without help from the cortex (driven by the spinal cord, not the brain)
- reaching: cervical spine CPGs
- walking: lumbar spine CPGs
what are some limitations to motor programming theory?
- this theory does not replace the impact of environmental or musculoskeletal variable, but instead helps to expand our understanding of movement
- a central motor program cannot be the sole determinate of action (ex. holding weights w/ shoulder flexed to 0 and 90: gravity impacts the movement)
what are some clinical implications of motor programming theory?
- don’t just train a single motion or isolated muscle; the problem may be from a higher motor center - stroke vs biceps tear
- this theory emphasized the importance of training the task and helping pts relearn the action
does dynamic systems theory focus on one system or multiple?
- focused on the interactions of MULTIPLE body systems
- interacting systems work cooperatively to achieve movement
- nervous system is a team, not a hierarchy
according to dynamic systems theory, how is movement considered?
- movement is flexible: motor equivalence (not just one way to complete a movement)
- also other control parameters that impact movement (ex velocity)
how does dynamic systems theory allow for motor variability?
- not an error (as described in motor processing theory) but as a necessary factor in optimizing movement
- low variability = highly stable movement pattern
– walking pace: not always easier to move slow –> variability in speed alters movement patterns
– ingrained movement patterns in our pts are harder to change; adjusting to a new movement pattern has more variability
