Ptp 512 neuroscience in physical therapy motor control issues and theories
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PTP 512 Neuroscience in Physical Therapy Motor Control: Issues and Theories. Min H. Huang, PT, PhD, NCS. Objectives. Identify individual, task, and environmental movement constraints Compare and contrast contemporary motor control theories

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Ptp 512 neuroscience in physical therapy motor control issues and theories

PTP 512Neuroscience in Physical TherapyMotor Control: Issues and Theories

Min H. Huang, PT, PhD, NCS


Objectives
Objectives

  • Identify individual, task, and environmental movement constraints

  • Compare and contrast contemporary motor control theories

  • Compare and contrast neurologic rehabilitation approaches with respect to assumptions underlying normal and abnormal movement control, recovery of function, and clinical practices.


Reflection
Reflection……

  • What is a theory?

  • What is the value of theory to clinical practice?




Environmental constraints on movement
Environmental Constraints Individual, Environmenton Movement

  • Regulatory

    • Essential elements that determine the movement, e.g. chair height

  • Non-regulatory

    • Feature that are not essential but may affect the performance, e.g. background noise


Individual constraints on movement
Individual Constraints on Movement Individual, Environment

  • Action

    • “goal-directed” movements

  • Perception

    • Sensory integration

  • Cognition

    • Mental functions underlying the establishment of a goal


Task constraints on movement
Task Constraints on Movement Individual, Environment

  • The nature of tasks determine the movement required.

  • Classify tasks by

    • Functional category, e.g. gait, bed-mobility, transfer

    • Discrete (definite ending) vs. continuous (no end point), e.g. grasping vs. walking

    • Stable vs. mobility, e.g. sitting vs. walking


Gentile s taxonomy for task classification
Gentile’s Taxonomy for Task Classification Individual, Environment

M: manipulation, Variability: inter-trial variability

+ present, – absent


Gentile s taxonomy for task classification1
Gentile’s Taxonomy for Task Classification Individual, Environment

M: manipulation, Variability: inter-trial variability

+ present, – absent


Motor control theories a tour through history
Motor control theories Individual, Environment– a tour through history


Discuss at your table group
Discuss at your table group Individual, Environment

  • What did the therapist do?

  • What did the patient do? How did the patient perform the tasks?

http://www.youtube.com/watch?v=mCiBehv_FOw&feature=related

http://www.youtube.com/watch?v=r5o5S-9zGpE


Reflex theory
Reflex Theory Individual, Environment

Reflexes are the building blocks of complex motor behaviors or movements


Reflex theory1
Reflex Theory Individual, Environment

  • Sir Charles Sherrington, the integrative action of the nervous system (1906)

    • Reflex chaining: complex movements are a sequence of reflexes elicited together

  • This is based on the observation that monkeys were unable to their arm after resection of one side of dorsal root ganglia.  Therefore, sensory inputs must be essential in initiating movements.


Limitations of reflex theory
Limitations of Reflex Theory Individual, Environment

  • Unable to explain

    • Spontaneous and voluntary movements

    • Movement can occur without a sensory stimulus

    • Fast sequential movements, e.g. typing

    • A single stimulus can trigger various responses (reflexes can be modulated)

    • Novel movements can be carried out.


Limitations of reflex theory1
Limitations of Reflex Theory Individual, Environment

  • Taub demonstrated that monkeys with bilateral deafferentation were able to move the arms. If with unilateral deafferentation, the monkey relearned moving the affected arm when the good arm was “constrained” in a sling. His findings lead to the constraint-induced movement therapy.

Stroke Rehabilitation: Constrained-Induced Movement Therapy

http://www.youtube.com/watch?v=MMTh2hWvB2g

Taub Therapy Clinic: Constrained-Induced Movement Therapy


Hierarchical theory
Hierarchical Theory Individual, Environment


Hierarchical theory1
Hierarchical Theory Individual, Environment

  • Higher centers are always in control of lower centers

  • Higher centers inhibit the reflexes controlled by lower centers

  • Reflexes controlled by lower centers are present only when higher centers are damaged

  • Neuromaturational theory of development

    • The brain determines infant behavior!


Hierarchical theory2
Hierarchical Theory Individual, Environment


Hierarchical theory3
Hierarchical Theory Individual, Environment

  • Based on the observation of motor development in children and adults

    • A child’s capacity to sit, stand, and walk is related to the progressive emergence and disappearance of reflexes

    • Brain stem reflexes (associated with head control) emerge before midbrain reflexes (associated with trunk control)


Current concepts related to hierarchical theory
Current Concepts Related to Hierarchical Theory Individual, Environment

  • Each level of the motor system can act on other levels

  • Reflexes are one of many processes of motor control


Clinical implications of hierarchical theory
Clinical Implications of Hierarchical Theory Individual, Environment

“When the influence of higher centers is temporarily or permanently interfered with, normal reflexes become exaggerated and so called pathological reflexes appear”…Brunnstrom, 1970

“The release of motor responses integrated at lower levels from restraining, influences of higher center, especially that of the cortex, leads to abnormal postural reflex activity”…Bobath, 1965


Limitations of hierarchical theory
Limitations of Hierarchical Theory Individual, Environment

  • Environment and other non-CNS factors can affect movement, e.g. Thelen’s experiments showed that baby’s stepping response re-emerges with body weight support

  • Normal adults exhibit lower level reflexes, e.g. flexor withdrawal

Body Sense. Scientific America Frontier. (1:00-2:40, 5:10-7:30)

http://vsx.onstreammedia.com/vsx/pbssaf/search/PBSPlayer?assetId=68932&ccstart=235620&pt=0&preview=undefined&entire=yes


Motor programming theories
Motor Programming Theories Individual, Environment

  • Concept of a central motor pattern or motor program

    • Many studies found that movement is possible even in the absence of stimuli or sensory input

    • Sensory inputs are not required to produce a movement but they are important in adapting and modulating the movement



Central pattern generator cpgs
Central Pattern Generator (CPGs) lesions

F flexor motoneurons

E extensor motoneurons

DC dorsal columns

DRG dorsal root ganglion

Rossignol, 2011


Evidence of a motor program central pattern generator cpgs
Evidence of a Motor Program: lesionsCentral Pattern Generator (CPGs)

  • CPGs are spinal networks capable of generating bilateral rhythmic movements, such as swimming or walking, in the absence of descending and sensory inputs

  • CPGs are network of interneurons that alternatively activate flexors and extensors on one side, and coordinate with CPGs on the other side


Motor programming theories1
Motor Programming Theories lesions

  • Motor programs are

    • Hardwired and stereotyped neural connections such as central pattern generators (CPGs)

    • Abstract rules for generating movements at the higher level

  • Motor program can be activated by sensory stimuli or by central processes



Limitations of motor programming theories
Limitations of Motor Programming Theories lesions

  • Does not consider that the nervous system must deal with both musculoskeletal and environmental variables to produce movements

    • e.g. identical neural commands to elbow flexors can produce different movements depending on the initial position of the arm and the force of gravity


Clinical implications of motor programming theories
Clinical Implications of lesionsMotor Programming Theories

  • Movement problems are caused by abnormal CPGs or higher level motor programs

  • It is important to help patients relearn the correct rules for action

  • Focus on retraining movements that are critical to a functional task, not just specific muscles in isolation


Systems theory bernstein s degree of freedom problem
Systems Theory: Bernstein’s Degree of Freedom Problem lesions

  • How does the CNS select a solution from an infinite number of possibilities for a task?

  • Solution

    • Higher levels activate lower levels while lower levels activate synergies, i.e. groups of muscles that are constrained to act together as a unit


Systems theory bernstein s degree of freedom problem1
Systems Theory: Bernstein’s Degree of Freedom Problem lesions

  • Viewed body as a mechanical system, involving the interaction between mass, external force (e.g. gravity), internal force

  • “Coordination of movement is the process of mastering the redundant degrees of freedom of the moving organism” (Bernstein, 1967)


Systems theory latash s principle of abundance
Systems Theory: Latash’s Principle of Abundance lesions

  • Synergy is a task-specific covariation of elemental variables with the purpose to stabilize a performance variable, i.e. minimize errors of a performance variable

    • Reaching: joint rotation angle stabilize hand position

    • Grasping: individual finger force stabilize total grasp force

    • Standing stability: postural muscle activation  stabilize COP


Systems theory latash s principle of abundance1
Systems Theory: Latash’s Principle of Abundance lesions

  • A muscle belongs to more than one synergy. Within a synergy, each muscle has a unique weighting factor that specifies the level of activation of that muscle within that synergy.

  • Synergies assure small variability of the performance variable while allowing relatively large variability of each elemental variable


Postural perturbation study: each lesionsmuscle may be activated to a different degree by each muscle synergy

Ting, 2005


Dynamic systems theory principle of self organization
Dynamic Systems Theory: Principle of Self-Organization lesions

  • Movement emerges as a result of interacting elements. No needs for specific neural commands or motor programs.

  • Variability of movement is normal. Optimal amount of variability allows for flexible, adaptive strategies to meet the environmental demand


Dynamic systems theory principle of self organization1
Dynamic Systems Theory: Principle of Self-Organization lesions

A new movement emerges when a control parameter reaches a critical value


Limitation of systems theory
Limitation of Systems Theory lesions

  • Nervous system is fairly unimportant

  • How do we apply mathematics and body mechanics to clinical practice?


Clinical implications of systems theory
Clinical Implications of Systems Theory lesions

  • Body is a mechanical system. Consider musculoskeletal factors underlying a patient’s movement problem

  • Changes in movements may not necessarily result from neural changes, e.g. faster vs. slow gait, speed during sit to stand

  • Encourage the patient to explore variable movements


Ecological theory gibson s perception action coupling
Ecological Theory: Gibson’s Perception-Action Coupling lesions

  • Action is specific to the task goal and the environment

  • Perceptual information of the environmental factors relevant to the task goal is necessary to guide the action

  • Limitations:

    • ↓ emphasis on nervous system


Clinical implications of ecological theory
Clinical Implications of Ecological Theory lesions

  • Individual is an active explorer of the environment for learning

  • Individual discovers multiple ways to solve movement problems in environment

  • Fundamental to the play-based therapy for pediatric patients

Baby Sense. Scientific America Frontier. (1:00-2:40, 5:10-7:30)

http://vsx.onstreammedia.com/vsx/pbssaf/search/PBSPlayer?assetId=68932&ccstart=235620&pt=0&preview=undefined&entire=yes


Discuss at your table group1
Discuss at your table group lesions

What are the assumptions of movement control underling each of these treatment approaches?

http://www.youtube.com/watch?v=r5o5S-9zGpE

http://www.youtube.com/watch?v=mCiBehv_FOw&feature=related



Motor control models lesions

Systems

Reflex

Hierarchical

Muscle reeducation

Contemporary task-oriented

Neurotherapeutic facilitation

Neurologic rehabilitation models


Muscle reeducation
Muscle Reeducation lesions

  • Change function at the level of muscle

  • Vera Carter, a practitioner beginning her work with muscle treatment of polio patients in Australia in the early 1930’s

Kendall Historical Collection


Assumptions of neurofacilitation approaches
Assumptions of Neurofacilitation Approaches lesions

  • Abnormal movement is a direct result of the neurologic lesion

  • Inhibit abnormal movement patterns to facilitate the normal movement patterns will lead to the return of functional skills

  • Repetition of normal movement patterns will automatically transfer to functional tasks


Reflex and hierarchical based neurofacilitation approaches
Reflex- and Hierarchical Based Neurofacilitation Approaches lesions

  • Brunnstrom, Rood, Proprioceptive neuromuscular facilitation (PNF), Bobath’s neurodevelopmental treatment (NDT)

    • Retraining motor control through “techniques” to facilitate and/or inhibit different movement patterns

    • e.g. PNF UE D1 Flexion/Extension http://davisplus.fadavis.com/kisner/Chapter06.cfm



Task oriented approach
Task-Oriented Approach approach)

  • Movement is organized around a behavioral goal and is constrained by the environment

  • Patients learn by actively attempting to solve the movement problem rather than by repetitively practicing normal patterns of movement.

    • e.g. RIC constraint-induced movement therapy camp http://www.youtube.com/watch?v=NhLsh1SW4Ak


Moving forward approach)

“….currently available evidence of dose–response relationships in motor learning, time-dependency of neuronal and functional recovery, and task specificity of treatment effects….…the lack of evidence as well as major changes over time in our understanding of underlying mechanisms about stroke recovery, which do not concur with the obsolete and constantly changing assumptions used to explain the Bobath Concept…”Kollen, 2009


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