lecture five: motor control and motor learning Flashcards
motor control
- defined as the ability to regulate or direct mechanisms essential to movement
- information processing related to activities carried out by the CNS that organize the musculoskeletal system to create coordinated, goal-directed movements
two control strategies of motor control
- feedforward strategy
- feedback strategy
nature of movement
- field of Motor Control is directed at studying the nature of movement and how movement is controlled
movement emerges from the interaction of which three factors?
- Individual (I)
- Task (T)
- Environment (E)
Factors within the individual, task, and environment affect organization of movement
action (individual)
- body is characterized by a high number of muscles and joints —> all must be controlled during execution of coordinated, functional movement
- multiple ways a movement can be carried out (multiple equivalent solutions)
- redundancy of human systems
- degrees of freedom problem
degrees of freedom problem
choosing among equivalent solutions and then coordinating the many muscles and joints involved in a movement
perception (individual)
- integration of sensory impressions into psychologically meaningful info
- sensory/perceptual systems provide info about state of body and features within the environment critical to movement regulation
- involves both peripheral sensory mechanisms and higher-level processing that adds interpretation and meaning to incoming afferent info
cognition (individual)
- cognitive processes include attention, planning, problem solving, motivation, and emotional aspects of motor control that underlie establishment of intent or goals
- within the individual, many systems interact in production of functional movement
- single vs dual task control
task classification two
- critical attributes that regulate neural control mechanisms
- discrete
- definite beginning and end
- continuous
- no recognizable beginning and end points
- end point is not inherent characteristic of task
- e.g. walking, running, swimming
- discrete
task classification three
- base of support is stable vs in motion
- stability: stable base of support (e.g. sitting or standing)
- mobility: moving base of support (e.g. walking or running)
task classification four
- whether object manipulation is required
- sequenced task: increase demand for stability (e.g. standing and lifting)
task classification five
- movement variability
- open movements: constantly changing or unpredictable environments
- closed movements: relatively fixed, predictable environments
understanding the nature of tasks can provide a framework for __________________ and can serve as a progression for _________________
functional evaluation; retraining functional movement
CNS must take into consideration attributes of the ___________ when planning _____________ movements
- environment; task-specific
- classified by whether features of the environment shape the movement itself
regulatory (environment)
- movement must conform to regulatory features in order to achieve the goal of the task
- these features shape the movement itself
- e.g. differently sized cups require different grasping patterns; walking on an uneven grassy surface impacts gait pattern differently than walking on a smooth floor
non-regulatory (environment)
- movement does not have to conform to these features
- may or may not affect movement
- e.g. background noise, lighting
theories of motor control
- reflex theory
- hierarchical theory
- motor program theory
- systems theory*
- dynamic systems theory*
- ecological theory
systems theory
- describes body as a mechanical system with many degrees of freedom that need to be controlled (bernstein, 1967)
- hierarchical control exists to simplify control of body’s multiple degrees of freedom
- higher levels of nervous system activate lower levels
- lower levels activate synergies, a group of muscles constrained to act together as a unit to solve DOF problem
as demands of a task __________, the control signals to synergy __________, leading to parallel _________ in activation in all muscles in the synergy
(systems theory)
increase; increase; increases
movements emerge from the interplay between the ____________, __________, and variations in the ______________
(systems theory)
- body system; external force; initial condition
- same central command can result in different movements
- different commands could result in the same movement
dynamic systems theory
- shares similar principles as systems theory but comes from broader study of dynamics or synergetics within the physical world
- movements could emerge as a result of interacting elements without the need for specific commands or motor programs within nervous system
“self-organization”
(dynamic systems theory)
- states that when a system of individual parts comes together, its elements behave collectively in an ordered way
- no need for a “higher” center issuing commands in order to achieve coordinated action
new movement emerges because of a critical change in one of the systems called __________
(dynamic systems theory)
- “control parameter”
- variable that regulates changes in the behavior of the entire system (i.e. control parameter = velocity)
main difference in dynamic systems theory
de-emphasizing notion of commands from CNS in controlling movement and seeking physical explanations
variability of motor control in dynamic systems theory has a _________ meaning compared to other motor control theories
- different
- variability is not considered a result of error but rather a necessary condition of optimal function
in the dynamic systems theory, optimal variability provides for…
flexible, adaptive strategies and allows for adjustment to environmental changes
too little variability can lead to _________
injury
(i.e. repetitive muscle strain)
too much variability can lead to __________
impaired movement performance
(i.e. ataxia)
task
nature of task being performed in part determines the type of movement needed so several classification parameters have been developed
task classification one
- functional categories
- bed mobility tasks
- transfer tasks
- walking and ADLs
a small amount of variability indicates a _____________ or a ___________, viewed as attractor state
highly stable behavior; preferred pattern
attractor well
the deeper the well, the harder it is to change preferred pattern, suggesting a stable movement pattern
which motor control theory is the best?
- any current theory is in a sense unfinished (always room to revise and incorporate new info)
- theoretical framework is the basis for clinical methods related to examination and intervention in patients with neurological problems
- theory helps us to generate research question and hypotheses about nature and cause of movement
early definition of motor learning
- study of the acquisition and/or modification of movement
- in the context of “recovery of function”, it referred to the re-acquisition of movement skills lost through injury
four concepts of motor learning
- learning is a process of acquiring capability for skilled action
- learning results from experience or practice
- learning cannot be measured directly, referred from behavioral changes
- learning produces relatively permanent changes in behavior
motor learning emerges from a complex of _________, __________, and ____________
- perception; cognition; action processes
- broadening definition of motor learning
- process of motor learning can be described as the search for a task solution that emerges from an interaction of the individual with the task and environment; task solutions are new strategies for perceiving and acting (newell, 1991)
- broadening definition of motor learning
performance
temporary change in motor behavior observed during practice
learning
relatively permanent change in behavior and involved in skill retention
with the patient as the learner, therapists will utilize teaching strategies like __________, __________, ________, and _________ to accomplish their therapeutic goals
instruction; feedback; practice; motivation
closed loop
- term originated in engineering
- closed loop control refers to control achieved by feedback such that the actual responses conforms to desired response (or set point) by means of correcting any difference between them
adam’s closed loop theory
sensory feedback from ongoing movement is compared with stored memory of intended movement (closed loop process)
open loop
- open loop control in motion systems means there is no position feedback of a moving object
- open loop motor control is the execution of preprogrammed movements, called a motor program, without perceptual feedback
- colloquial term is “muscle memory” (e.g. gymnasts practice hours until they can execute complex routines effortlessly)
schmidt’s schema theory
emphasizes “open-loop” control processes and generalized motor program concept
theories related to stages of learning motor skills
focus on motor learning from a “temporal perspective” and describe how learning occurs over time
cognitive stage (fitts and posner three stage model)
- “what is it that must be done?”
- involves understanding task and selecting a strategy for optimal performance
- characterized by large number of errors and requiring a high degree of cognitive activity such as attention
- improvements in performance are large
associative stage (fitts and posner three stage model)
- “how should it be done?”
- best strategy has been selected
- begins to refine skill
- characterized by small variability of performance and slow improvement in performance
autonomous stage (fitts and posner three stage model)
- “what presents success?”
- perform skills automatically with low level of attention
- person is ready for advanced challenges such as dual task performance
novice stage (systems three stage model)
- “freeze degree of freedom”
- learner simplifies movement by stiffening body segments (i.e. fixing angles of many joints) in attempt to control DOF and complete task
- learner can perform task accurately but inefficiently
advanced stage (systems three stage model)
- “release additional of degree of freedom”
- bio mechanical constraints and DOF are being refined
- muscle synergies across number of joints would be used to create a well coordinated movement
- contraction of agonist and antagonist is reduced
expert stage (systems three stage model)
- “release all degree of freedom”
- learn to use energy more efficiently by taking advantage of passive forces increasingly in movement control and reduce fatigue
- movements are optimally controlled
stage one (gentile two stage model)
- understand the requirements of the movement
- goal of the task
- develop and appropriate movement strategy to achieve the goal
- task and environmental features critical to the movement
- learn to distinguish relevant, or regulatory, features of the environment from those that are non regulatory
stage two (gentile two stage model)
- refine the movement (fixation/diversification)
- develop capability of adapting movement to changing task and environmental demands while performing task consistently and efficiently
- closed skills require “fixation”
- have minimal environmental variation and require movement consistency
- open skills require “diversification”
- performed in changing environments and require movement diversity
acquisition or practice phase
- initial fumbling attempts
- skills are learned or relearned
- indicates “performance”
retention and transfer phase
- mastery of a skill
- information stored for retrieval and application to novel situations
- indicates “learning”
practice
- continuing and repetitive effort to become proficient in a skill
- practice should be ACCURATE, since faulty practice may lead to development of bad habits and inefficient postures
- practice should be ACTIVE, not passive, and initiated by the patient
- practice should incorporate enough VARIABILITY to allow patient to explore perceptual motor workspace and to discover solutions to movement dilemmas
- practice should be TASK SPECIFIC
feedback
- refers to the use of sensory information for the control of action in the process of skill acquisition
- powerful variable affecting learning
intrinsic feedback
- via various sensory systems
- may be distorted in patients with neurological lesions
- i.e. visual info regarding if movement was accurate and somatosensory info about position of limbs during movement
extrinsic feedback
- come from external resource
- purpose is to provide person with Knowledge of Results (KR) or Knowledge of Performance (KP)
- KR: outcome of movement; terminal feedback
- KP: movement pattern (i.e. kinematic feedback)
- i.e. telling patient to lift their foot higher to clear an object while walking
massed vs distributed
- massed practice
- session in which amount of practice time in a trial is greater than amount of rest between trials
- distributed practice
- session in which amount of rest between trials is equal to or greater than amount of time for a trial
constant vs variable
- constant
- learners practice a skill repeatedly under the same parameter setting
- variable
- learner practice a skill under a variety of parameter settings
random vs blocked
- random
- learned practice a set of motor tasks in a random order
- blocked
- learners practice a set of motor tasks in a fixed order
whole vs part
- whole
- practice entire movement at once
- part
- break down task into different components
transfer
amount of transfer is dependent on similarity between two tasks/environments so that neural processing demands would be similar
mental practice
(supplementary motor cortex) does enhance skill acquisition
guidance vs discovery
- presence of physical guidance
- unguided conditions less effective for immediate skill acquisition but more effective for transfer
the brain is a dynamic organ and some degree of ___________ continues throughout lifetime of an individual
plasticity
key learning elements for all ages include
- environmental considerations
- motivation
- attention
- guidance and instruction
- selection of feedback and practice
older adult performers seem to benefit greatly from __________________, especially when learning closed motor skills
cognitive learning strategies
intellectual abilities of healthy people do not lesson although performance skills that are _________ tend to demonstrate a noticeable _________
time related; decline
processing of new information typically takes ________ due to normal age-related changes in the CNS
- longer
- without cognitive assistance, procedural leaning of motor programs may become the only available avenue for regaining function control over movement
when working with older adults, adapting both the principles of ___________ and the __________ in which skills are practiced are key elements
motor learning; environment
mental practice is _____________ for older adults
- highly effective
- ability to learn is dependent on
- intelligence
- learning skills acquired over the years
- flexibility of learning style
- various non cognitive factors
- ability to learn is dependent on
