motor learning and recovery of function

motor learning

acquisition and re-acquisition of movement

involves learning new motor & sens strategies

emerges from interaction of perception/cognition/action

recovery of function

new solutions in specific tasks & environment given new constraints on individual by neural pathology

performance

in the moment—temporary change in motor behavior seen during practice sessions

learning

acquisition or modification of movement

results from experience of practice

produces relatively permanent changes in behavior

tested outside context and/or timeframe of training

distinct and separate from practice

which part of the brain is involved in memory?

hippocampus—encoding

neocortex (anterior cingulate especially)—recall

declarative/explicit memory

facts & events

nondeclarative/implicit memory

nonassociative learning: habituation and sensitization

associative learning: classical and operant conditioning

procedural learning: tasks and habits

declarative/explicit memory areas involved

medial temporal lobe

sensory association cortex

hippocampus

nonassociative learning areas involved

reflex pathways

associative learning areas involved

emotional responses: amygdala

skeletal musculature: cerebellum, deep cerebellar nuclei, premotor cortex

procedural learning areas involved

striatum and other motor areas (cerebellum, etc.)

explicit motor learning

verbal knowledge of movement performance=declarative memory

understanding how to do something

effortful processes bring about change in performance—paying attention to how a movement feels so you can modify next attempt, consciously discovering rules for movement

result: being able to say what you did or how to do something

implicit motor learning

no or minimal increase in verbal knowledge of movement (declarative memory) but improvement in movement performance (procedural memory)

being able to do something

no conscious attention to task—initially unaware, may stay unaware

unable to verbalize what was learned

“habit learning”

non-associative learning

nervous system learns response by repeated exposure to stimulus

habituation & sensitization

habituation

diminished responsiveness from repeated exposure to non-painful stimulus

ex. wearing clothes—there’s always sensory input, but you’re not always consciously processing the feeling of clothes on your body

sensitization

amplified responsiveness following a threatening, painful, or noxious stimulus

classical conditioning

training a response to occur following stimulus even though it was previously associated with another stimulus (Pavlov’s dogs)

operant conditioning

trial and error based

task we’re learning leads to + or - outcome, we learn with ± reinforcement/punishment

neural contributions to implicit/procedural learning & memory

no single area of brain

3 critical subcortical areas: cerebellum, BG, sensorimotor cortex (supplementary motor area!!!)

cerebellum

monitors and updates movement using sensory feedback

adjusts motor output to bilat cortex

uses sensory info to guide procedural learning

basal ganglia

coordinates neural processes across brain regions

involved in movement response selection (changing movement/direction)

ex. PD pts have trouble turning, crossing thresholds

supplementary motor area

activates with initiation of movement and motor coordination

sensorimotor cortex

active when explicit knowledge unavailable, learning is implicit

more active after movements sequence becomes automatic

can be utilized to drive motor learning when explicit learning systems are damaged

neural contributions to explicit/declarative learning

hippocampus

medial temporal cortex

amygdala

prefrontal and premotor cortices

hippocampus & medial temporal cortex

critically support formation of declarative learning and memory

damage→decr ability to form declarative knowledge, retain ability for procedural learning

ex. amnesia, encephalitis, alzheimer’s

prefrontal cortex

allows declarative learning to be held in working memory, used to guide motor performance

damage→decr ability to integrate declarative knowledge into movement

premotor cortex

important in sequence & timing via external cues, explicit instructions

damage→decr ability to integrate declarative knowledge into movement

repetition can…

convert declarative skill into procedural (automatic)

declarative learning allows pts to do what?

practice even when physical conditions will not allow it (increased repetition) via mental rehearsal

declarative requires the pt to be…

highly motivated

able to attend fully to task

able to integrate new info to info they already know about the task

can be mediated by PT

what if explicit/declarative learning is compromised?

implicit/procedural learning can be maintained

ex. HD, alzheimer’s, MS, brain injury

delivery of declarative instructions disrupts procedural learning in post-stroke pts

things to think about with pts with impaired declarative learning

evaluate and consider impact of verbal instructions

are instructions enhancing or hurting motor learning?

fitts & posner stages of motor learning

1. cognitive phase

2. associative phase

3. autonomous phase

cognitive phase

understanding what to do

high attentional demands

declarative, high performance variability

associative phase

knowing how to do it

less attention required

mostly implicit, low performance variability

autonomous phase

doing it well

low attentional demands, easier to multitask

implicit

schmidt’s schema theory

creation of 2 schemas (motor & recognition sensory) leading to development of a motor program→apply to variety of contexts

motor program

set of general rules of spatial-temporal patterns for a type of movement

schema theory: 4 things available for storage in short term memory

initial movement conditions

parameters

outcome of movement

sensory consequences

schema theory: where does info go from short-term memory?

recall schema, recognition schema

learning consists of ongoing process of updating these schemas w/ each movement made

limitations of schema theory

strong support in children, less in adults (few adults would not have some exp of movement while children are naive to many)

lacks specificity; how does schema processing interact w/ other systems/interact for initial movement

schema theory clinical implications

vary environment in order to pull different motor programs and select which is most appropriate

ecological theory

perception & action systems mapped into optimal task performance through exploration of perceptual/motor workspace

suggests need to indentify critical perceptual variables

roles of perceptual info

prescriptive

feedback during & on completion of movement

can be sued to structure search for a perceptual/motor solution

ecological theory: how to facilitate learning

help learner understand nature of perceptual/motor workspace

help learner understand natural search strategies used

provide augmented info to facilitate search

ecological theory: transfer of motor skills

dependent on similarity of tasks, relatively independent of muscles used or objects manipulated

clinical implications of ecological theory

pts must learn perceptual cues that will help identify optimal strategy

pts must learn to discriminate btwn regulatory and non-regulatory cues

2 stage model

understand task dynamics: goal, movement strategies, environmental features

fixation/diversification: refine movement; consistency, efficiency, adaptability

bernstein 3 stage theory

focuses on controlling degrees of freedom of body segment during movement

novice stage, advanced stage, expert stage

novice stage

learner simplifies movement by controlling DOF

constraint at cost of efficiency and flexibility of task

advanced stage

gradual release of DOF

reduced co-contraction and incr in use of synergies

expert stage

all necessary DOF released

use of passive forces to incr speed and reduce energy cost

most efficient & coordinated performance

testing performance

look at what happens during practice

testing learning

retention testing: period of no practice of specific task, then same task in same context

OR

transfer test

both indirect tests, distinguish learning from performance

transfer testing

different task in different context, but related to original task (ex. original task STS, different task standing up from floor)

stronger test of learning=addresses adaptability of skilled movement

concept of savings

=time saved when relearning a task vs. time needed w/ initial learning

ex. riding a bike takes a long time to learn at first, but each time you ride a bike you become familiar with how to do it after a few pedals