Exam 1- motor control theories

questions to ask for movement analysis

1. what does the task demand

2. what systems in the movement system are involved (sensory, proprioceptive, msk, neuromuscular)

3. what is the “expected outcome”

4. what are the environmental characteristics of the task

closed task

task with predictable, replicable environment

open task

task with a variable environment, will likely look a little bit different every time due to the circumstances/environment

stability task

non-moving base of support

mobility task

moving base of support

manipulation task

UE used, need to change balance to counteract UE movement

non-manipulation task

no UE/hand used, likely focused on lower body/core

continuous task

arbitrary beginning and end of the task

ex. writing, running

discrete task

set beginning and end of task

ex. sit down, stand up

reflex theory

• idea that reflexes are the building block of movement and every movement is a reflex caused by an event in the environment

• “brain is unimportant” and does no decision making in movement

• allows for:

  • interpretation of movement with and without a reflex, we can enhance/downplay reflexes during a motor task, use known reflexes to help movement when MC is impaired

• limitations: doesn’t explain internally motivated mvmt or fast mvmt

Hierarchical theory

• idea that there is top-down control of the brain, the CNS tells lower brain centers what to do

• assumes that neuromaturation/corticalization is the only reason for change in development/control

• (reflex-hierarchical assumes that the upper brain can modify lower, primitive reflexes)

• allows for: explains disordered motor control in pts with neurological disorders, bc the CNS can’t regulate the lower reflexes

motor programming theory

• idea that the brain creates general rules for movement classes (order of events, relative timing, relative force)

• think motor program/central pattern generator

• explains the ability to generate different movements with the same motor programs and the ability to produce novel movements by specifying new parameters

  • relies on synergies between muscle groups

• allows for: retraining movement should involve functional tasks, not just NM re-education

synergies

patterns of relative muscle activation

• during grabbing, biceps and triceps will fire

principle of abundance: synergies used to ensure flexible and stable performance of motor tasks

systems theory

• sees the body as a machine that is subject to the laws of physics and forces

• some central commands have different outcomes based on the conditions of the system

• believes hierarchical central systems exist to provide control over redundant DoF

dynamic systems theory

• principle of self organization

  • when a system of individual parts come together, elements behave collectively in predictable ways

• non-linear system

  • output of systems are sometimes not proportional to the input and are dictated by a control parameter

• variability

  • control parameter: variable that regulates change in behavior of an entire system

  • attractor well: ease with which a movement can change

• limited: doesn’t involve CNS/interactions/environment

• gains: interaction of elements of the body, retraining should INCLUDE errors!

Ecological theory

• idea that environment changes movement

• perceptual info informs actions

• limit: minimizes importance of nervous system input, sees environment as driver of mvmt, lack of research

• allows: individuals should actively explore the environment, multiple ways to accomplish a task, adaptability of tasks is important, pt learns to distinguish perceptual cues to organize action

neurofacilitation (rehab)

• retrain motor control through facilitation/inhibition of different motor patterns

• includes PNF, sensory integration therapy

• TL;DR use specific stimulus to get a response

• assumes that damage to the cortex will stop regulating lower brain centers and that’s why movement is abnormal

task-oriented approach to rehab

• adapting to the environment is key to recovering function

• when retraining mvmt, focus on functional tasks

• allow pt to learn by actively solving problems inherent to functional tasks

motor learning vs performance

• learning is a process of acquiring capability for skilled action and is the result of practice

• performance is a temporary state of motor behavior, often observed during practice.

  • depends on pt’s mental state, body structure and function, degree of learning

implicit learning

• non-declarative, not fact linked, unconscious

• relies on procedural learning→ acquire via practice, develops a motor schema

  • procedural learning= involves frontal lobe, basal ganglia, parietal lobe, cerebellum

• ex. riding a bike

• associative vs non-associative

  • non-associative: no stimulus associated with response, reflex pathways

    • habituation

    • sensitization

  • associative: classical conditioning, pair stimulus with consequence→ amygdala, cerebellum, deep cerebellar nuclei, premotor cortex

    • operant= associate behavior with consequence, rat-box

    • classical= linking stimuli together

explicit learning

• declarative, factual knowledge

• requires attention, awareness, and reflection

  • declarative learning= medial temporal lobe areas, hippocampus, sensory associative nucleus

• encode info→ consolidate→ store→ retrieve info

• relies on feedback systems

open loop feedback

• control is feed-forward, use what you learn about your action AFTER it has happened and apply it to the next action

• often works with faster tasks

• ex. swinging at a baseball pitch

closed loop feedback

• control is feedback, info about movement and adjustments are made while the movement happens

• feedback is helpful during the current trial

Schmidt’s schema theory

• schema= cluster of abstract info about a concept in long term storage

  • set of movement-related rules that are developed with experience

• generalized motor program= rules for creating spatial and temporal patterns of effector activity needed to execute a specific movement, can be modified and applied to new situations to create new schemas

  • built upon schemas

• recall schema= info needed before creating a motor action that is used to select a response

• recognition schema= used to evaluate response formed in relation to sensory consequences/mvmt outcome/initial conditions

• limits: lack of specificity in interacting with other systems during learning and doesn’t account for immediate acquisition of new skill

• allows for: optimal learning means practicing under many conditions

Fitts and poster 3 stages of motor learning

• cognitive- learn rules, think about task a lot

• associative- refine skills, focus on particular patterns

• autonomous- do it without thinking

Bernstein’s 3 stages of motor learning

• 1st/beginner- reduce DoF of jts to focus on what’s important/external support from other jts

• 2nd/advanced- release additional DoF

• 3rd/expert- release all DoF and move fluidly

Gentile’s 2 stage of motor learning

• stage 1- understand the task dynamics

• stage 2- refine mvmt and adapt to changing task/environment, perform consistently and efficiently

massed practice

• do a whole lot of practice with little rest

• better in beginning of training

distributed practice

• do more rest time than practice time

• better retention later on→ requires repeated retrieval of motor command from long term memory

blocked practice

• practice one skill at a time

• better initially

random practice

• switch up order of skills that are practiced

• better for retention adn transfer of skills

part vs whole practice

• part= a specific section of a skill

• whole= the whole skill

intrinsic/extrinsic feedback

• intrinsic= inherent info from a movement, what a person can sense within themself

• extrinsic= augmented/supplemental info (ex. force of a PT’s hands, score on a dive)

knowledge of performance/results

• KP is feedback about a movement the learner made, goal is to correct movement

• KR is terminal feedback about the consequence of the movement

  • quantitative OR qualitative→ you missed vs. too far to the left

absolute/relative frequency of feedback

• absolute= # of times feedback was given in a session

• relative= % of trials that got feedback

substitution (of function)

• when one motor strategy doesn’t work to accomplish a task (post injury), an alternate one is used to complete the task/activity

factors affecting recovery of fn

• stage of development (age)

• characteristics of the lesion (size, location)

• pre-injury neuroprotective factors (exercise habits, environmental enrichment)

• post-injury factors (pharmacological tx,

plastic/declarative learning

• occurs in temporal lobe and hippocampus

• associated with long term potentiation

skill acquisition and neural location

• early= all over the brain (prefrontal cortex, bilateral sensorimotor cortex, parietal lobe, cerebellum, caudate nucleus)

• late= cerebellum, basal ganglia

types of neural damage

• diaschisis- transient, structurally intact brain loses fn due to loss of input

• local edema- adjacent to injury site

• generalized edema- distant to injury site

• cytotoxic cerebral edema- accumulation of intracellular fluid (edema in neuron)

• vasogenic edema- inc permeability of capillary cells see leakage of proteins from damaged blood vessels

axon regeneration in CNS and PNS

• CNS→ oligodendrocytes and axon’s won’t regenerate. glial scar prevents it

• PNS→ schwann cells regrow quickly and create a “track” for axon to regrow

intracellular response to neural injury

• denervation supersensitivity

• unmasking silent synapses