Motor control theories and principles of neuroplasticity (lecture 2, week 3)

what is motor control

how we move

what is motor learning

how we learn to move or make changes

what are motor control theories

a group of abstract ideas about movement organization in an unobservable process

what two questions to motor control theories attempt to answer

the role of brain structures and sequencing activation and parameters of which the CNS controls

is there an answer to which motor theory is correct

nope

why are motor learning theories important

to interpret behavior with our patients, predict or explain these behaviors, understand typical movement

Why do PTs need to know and understand neural basis

to understand typical movement control and the pathophysiology of impaired movement

what are the 6 motor control theories

reflex theory, hierarchal theory, motor programming theory, systems and dynamic systems theory, ecological theory, brooks theory of motor control

who created the reflex theory

charles Sherrington in 1932

what is the idea behind the reflex theory

reflexes are the building blocks of all movement and complex movements are a result of reflex chains

reflex theory limitations

reflexes integrate as we age, does not explain movement in absence of sensory info, does not explain movement too fast for reflexes, does not explain production of novel movement, does not explain how the same stimulus can produce different movements

reflex theory influences

early treatment has strong reliance on stimuli, too much emphasis on evaluating reflex status rather than active motor control abilities

the reflex theory highlights

how the CNS uses simple and complex reflex pathways as a component of motor control

who creates the hierarchial model

john hughlings jackson

what does the hierarchical model state

the brain has higher, middle, and lower levels of control. Each level in the CNS exerts control over lower levels for motor control. Higher centers inhibit the lower centers. Higher centers mature and develop as we learn.

based on the hierarchial model what reflexes are present when higher level centers were damaged

low level reflexes

hierarchical model limitations

it is simple and inaccurate. a top down model is incorrect. higher centers are not inhibitory.

hierarchical model false assumptions in PT

if we inhitir abnormal reflexes normal movement will emerge, reflex inhibition is necessary for normal motor function, sensory inputs are used to inhibit reflexes to improve higher level control

what is the motor programming theory

a preplanned strategy can be activated by sensory stimulus or central process. It explains a series of subroutines are organized into correct sequence to perform a movement or motor skill.

what are the three types of motor programs in motor programming theories

open loop, closed loop, generalized motor program

what is an open loop program

CNS is the executive decision that leads to effector output through the spinal cord and muscles. Decisions are made before performing the skill and you cannot adjust or stop the movement.

what is a closed loop program

when the CNS leads to effector output and then movement which results in the CNS receiving sensory feedback to drive movement. You can make adjustments as you are completing the movement.

limitations to the motor program theory

cannot be the sole determination of action, storage problem, novelty problem where a person cannot create new movement based on this theory

motor program theory implications

retraining functional tasks vs. re-educating specific muscles in isolation, performing tasks in a variety of positions / situations

who developed the systems theory of motor control

nikolai bernstein

what is the systems theory of motor control

movement are effected by interactions among multiple systems and the whole body is a mechanical system with mass that is subject to external forces

what is the hierarchical model of balance in the systems theory of motor control

equilibrium / protective reactions to righting reactions to tonic neck reflexes to stretch reflex

what is the degrees of freedom problem in systems theory

there are many parts that need to be controlled and a hypothexied hierarchical control exists to control multiple DOF via higher levels that activate lower levels.

what are synergies

when a group of muscles are co-trained to act together as a unit

what are control parameters for dynamic system theory

a variable that regulates change in the behavior of the entire system. behavior changes are based on outside factors.

movement is at the center of what characteristics

task, individual, and environment

what is the ecological theory

the goal of motor control is the control of movement to accomplish a particular task. Movement is organized around a goal directed behavior and the perception of environment input is relevant to action.

what are clinical implications to the ecological theory

critical aspects of neuro rehab are controlling and manipulating the environment

what are limitations to the ecological theory

there is less emphasis on the organization and function of the nervous system

what is the brooks model of motor control

there is a heterarchy that incorporates both hierachy and systems theory. It is a flexible organization system with different levels responsible for different roles in motor control. It suggests task systems contain higher and lower CNS parts based on the task, emotion, and experience of the subject.

what does brooks model of motor control utilize concepts from

open and closed motor loop / program theories

based on brooks model of motor control what do the highest levels involve

developing plans for movement and perceptions for action. This may involve the cortical association areas, limbic system, and caudate of the basal ganglia.

based on brooks model of motor control what do the middle levels involve

converting movement strategies to tactical commands, motor programming, and the cerebellum, putament of the basal ganglia, primary motor and sensory cortex, and brainstem

based on brooks model of motor control what do the lowest levels involve

executing motor commands, servo-redulation of ongoing movement, includes the CNS brainstem and spinal cord along with the PNS motor and sensory nerves

why does the higher levels involve the strategic planner

it thinks of the overall plans or needs for the motor task

why is the limbic system in the higher levels

it controls motivation and emotional regulation

why are the cortical association areas in the higher levels

it interprets perceptions of the world and task goals

what is the caudate of the basal ganglia in the higher levels

it controls automaticity and coordinating learned motor tasks

what is the goal of middle levels

convert general plans or strategies into specific tasks

why is the putamen of the basal ganglia in the middle levels

it helps with postural control, direct connection to the brain stem, and commands the motor cortex

why is the cerebellum in the middle levels

it helps with control, comparator and adjustor based on feedback, and plans via feedforward control

why is the sensorimotor cortex in the middle levels

it has direct and indirect connections to alpha motor neurons, provides structure for motor output at the spinal cord level, and regulates spinal reflex activity.

what is the goal of the lower levels

boots on the ground to examine how movement should be executed

why are interneuron pools in lower levels

to process and integrate descending commands, incoming sensory info, and propriospinal feedback in the spinal cord

why are motor neurons in the lower levels

it is the final pathway for motor output

why are central pattern generators (CPGs) in the lower levels

they are hardwired subroutines in the spinal cord activated by higher centers or sensory inputs

why are spinal reflexes in the lower levels

they are hardwired circuitry at the spinal cord level.

what is the inegrated systems approach

where movement emerges from the interaction between the individual, the task attributes, and the environment constraints. Movement is a dynamic interplay between perception, cognition, and action systems

what might affect the movement outcome

a change in any subsystem

in neuro ICF models may include

recovery and compensation

what are some factors that affect recovery of function

biological such as age, weight, gender, lesion size, neurotrophic factors AND environmental factors such as pre-injury factors and behaviors and post injury factors

what is neuroplasticity

the ability of the CNS to change or adapt in response to internal and external influences, such as activity dependent learning, aging, brain injury, and post lesion experience / environment

what is the foundation for all learning

neuroplasticity

what does neuroplasticity involve

functional reorganization and synaptic and dendritic plasticity

can neuro plasticity occur faster in younger or older people

younger

when does your brain remodel

always!

what is adaptive plasticity

plasticity that leads to an increase or improvement in function

what is maladaptive plasticity

plasticity that leads to a disruption of function and may be considered a disease state such as neuropathic pain or some compensatory changes

what are some principles of neuroplasticity

use it or lose it, use it and improve it, specificity, repetition, intensity, time, salience, age, transference, interference

why does age matter with plasticity

synaptic potentiation, synpatogenesis, and reorganization is reduced with aging.

why does time matter with plasticity

the earlier you intervene the better outcomes

what is interferene

new learned compensatory strategies form and impede the ability to use plasticity to recover of typical funtion

what is transference

learning one skill can improve ability in another skill that is biomechanically similar . Think spill over effect

transference is contrasted with

specificty

what is task specificty

task training should match task demands and environment as closely as possible

what should you think about with specificty

components and prerequisites of the skill, task characteristics (open vs close chain, sitting vs standing) and what the environment looks like

discrete movement tasks

have a recognizable end and beginning. ex) kicking a ball

continuous tasks

the endpoint is not inherent but is decided arbitrarily by the performer. ex) running

open movement tasks

requires performers to adapt to movement strategies in a constantly changing and often unpredictable environment

closed movement tasks

tasks performed in relatively fixed or predictable environments

stability tasks

in sitting or standing with a non-moving BOS

mobility tasks

have a movign BOS

manipulation tasks

involve movement of the upper extremities

what is salience

the quality of being particularly noticeable or important. Should be engaging and fun!

exercise of moderate to vigorous intensity increases the production of

BDFN which is a protein that increases synaptic transmission and dendritic contacts

how can you calculate intensity in neuro PT

HR max and target HR zones, RPE, short specific rest breaks, active recovery

optimal daily target for repetition to help with neuroplasticity

400-600 reps per day of challenging functional tasks

what should you consider with repetitions

Pt frequency, HEP, practice designs

why do we need to use neural circuits

to develop functional and efficient pathways

post injury is a time of

heightened plasticity as well as heightened vulnerability