Intro to theoretical perspectives and Rehab models

Motor Control

-an area of study dealing with the understanding of neural, physical, and behavioral aspects of movement

-ability to regulate or direct the mechanisms essential to movement

information procesing

-use of sensory input, motor output, and central integrative structures to produce coordinated movement behaviors

Stages of information processing

1. stimulus ID

2. Response selection

3. Response programming

Stimulus ID

decide where a stimulus has been presented and, if so, what it is

Response selection

-decide what response to make, given the nature of the situation and environment → what to do and how to do it (motor plan)

Response programming

-prepare the motor system to make the desired movement (motor program)

Types of information processing

Serial processing and parallel/distributed processing

Serial processing

a specific, sequential order of processing info

Parallel/distributed processing 

processing of info that can be used for more than 1 activity by more than one center simultaneously, allows dual task performance

Outcome of information processing

-Movement output (response execution; influenced by feedforward & feedback)

3 Main Theories of Motor Control

-Reflex theory

-Hierarchical Theory

-Systems Theory

Reflex theory

-Based on Sir Chales Sherrington (late1800s/ early 1900s); Studied reduced cat preparations (ablated above midbrain); Awarded 1932 Nobel PrizeR

Reflex theory major assumptions

-Reflexes are the basis for all movement

-Chains of reflexes result in normal movement

-The nervous system is a passive recipient of sensory stimuli that triggers, coordinates, and activates muscles

Reflex theory basic structure

-Receptor→conductor→effector

-Stimulus→sensory systems→stereotypical movement (reflexes)

-Stimulus→Response

Reflex theory is a “peripheralist” approach to motor control, explain…

-External stimulus leads to movement

-Sensory stimulus is necessary for motor output

-Reflexes are considered the basis of all movement

How would the reflex theory guide PT practice?

-Tactile cues

-Stretch reflex (quick stretch)

-Guidance

-Perturbations

-DTR

-Functional e-stim

-CN testing

-Sensation screening

Limitations of Reflex Theory

-does not adequately explain spontaneous and voluntary movements

-Reflex cannot be the basis of all motor behavior if an outside stimulus is not required to initiate movement

-Movement is possible in the absence of sensory input

-Does not adequately explain fast/ballistic movement that occurs too rapidly for the use of sensoru feedback to trigger the next movement

-Reflex chains do not adequately explain the variation in responses that may occu from the same stimulus

-Reflexes do not explain the ability to produce novel movements based on experience (ie. violinist playing a cello)

Hierarchial theory

Based on the work of JH Jackson, an English physician (late 1800s), and others, the evolutionary approach, and clinical observations of patients

Hierarchial theory major assumptions

-Control organized hierarchically → “top down” unidirectional flow

-Voluntary movements initated by “will” (higher levels)

-Reflexive movements described as primitive (childlike); eventually inhibited by higher motor centers

Hierarchical theory is a “centralsist” approach to motor control, explain…

-Internal origin of movement

-Centrally driven control leads to motor output

-Reflexive movements dominate only after CNS injury → “Release” from higher control

-Low-level primitive reflexes only “block” higher level coordinated movement patterns (negative signs(-): loss of function (weakness); positive signs(+): release of previously suppresed abnormal reactions (spasticity))

Hierarchical theory basic structure

-It gives a pyramid scheme

-”top → down” approach

How would the hierarchical theory guide PT practice?

-cueing

-Guiding/blocking abnormal reflexes/movements

-Retraining to “normal” state, pt needs the want/will to achieve this normal in order for this to work

Hierarchial theory limitations

-Cannot explain the dominance of reflex behavior (low level) in certain situations in normal adults (ie. stepping on a pin → immediate reflex; bottom-up control)

-Not all movement is initiated from higher centers

-Cannot assume that all low-level behaviors are primitive, immature, and non-adaptive, while all higher-level/cortical behaviors are mature, adaptive, and appropriate

-Central motor pattern/motor program - more flexible than the concept of a reflex because it can be activated either by sensory stimuli or by central processes) (Central pattern generators (CPGs) - spinally mediated motor programs; research in cat model found CPGs by themselves can generate complex movements as they walk, trot, and gallop)

Systems Theory

-based on work of Russian neuroloi=gist Nikolai Bernstein (early-mid 1900s); writings fros from 1932 translated to english 1967; biomechanical background

-Described distributed control system

-Movements not peripherally or centrally driven; strategies of motion emerge from dynamic interaction among many situations - each contributing to different aspects of control (influenced by internal factors like joint stiffness, inertia, forces, and external factors like gravity)

Bernstein viewed the human body as a _____ system with _____ degrees of freedom that need to be controlled

mechanical; numerous

Coordinative control strategies allow…

“matering the redundant degrees of freedom”→ synergies

Continuous comparison (feedback) within the systems theory

-Constantly modifies control for the most effective & efficient means to meet task goals (closed loop)

Systems theory major assumptions

-understand the body as a mechanical system→ strategies of movement emerge from the interaction of many cooperative systems

-nervous system adapts to and predicts constraints placed on movement by the physical laws associated with the musculoskeletal system and its environment

-accounts for the flexibility and adaptability of the nervous system (plasticity; shifting locus of control)

-The nervous system is organized to control goal-directed behavior → task-specific

How would systems theory guide PT practice

-Dual tasking intervention

-Functional assessments (5x STS, Tinetti, TUG)

-Functional goals

-Patient-centered care

Systems theory limitations

-Bernstein considered the contributions of the nervous system, MSK, gravity, and inertia to predict motor behavior- did not explore other environmental factors, cognitive/perceptual influences, and open-loop control

-Many variations of a “systems” model, creating some confusion with terminology and application

Movement comes from what three interactions

-Task

-Individual

-Environment

“Task” subcomponents

-Mobility

-Postural control

-UE function

“Individual” subcomponents

-Cognitive

-Sensory/perception

-Motor/action

“Environment” subcomonents

-Regulatory (surface standing on, people walking in front of patient)

-Non-regulatory (lighting, room noise)

Neurologic Rehab Models

-Muscle Re-education

-Neuropathic Facilitation Model

-Contemporary Task-Oriented Model

Muscle re-education

-NOT based on neurophysical motor control model, but on knowledge of groos muscle anatomy and on faith in human willpower

-Focused on the use of manual muscle testing to identify weakened muscles and specific exercise to strengthen isolated muscles (“re-education”)

-Advocated by Sister Kenney for tx of polio (1940s/50s)

Muscle re-education rehab model assumes…

-Patients can consciously channel their neural energy to activate individual muscles and motor units (like biofeedback)when provided with appropriate feedback

-Avoids secondary complications and ineffective, inefficient compensatory movement patterns

-Provides bracing to correct/prevent deformity -ortho focus

Why would the muscle re-education rehab model lead to dissatisfaction in PT practice?

Doesn’t have much focus on function, more on strength to re-educate the affected muscle

Neurotheraeutic facilitation rehab model

-Based on reflex and hierarchial models of motor control

-developed by PTs and physicians in the 50s/60s

Neurotherapeutic facilitation model common assumptions

1) The brain controls movement, not muscles

2) We can alter or facilitate, a patient’s movement patterns by applying specific patterns of sensory stimulation, especially through proprioceptive afferent pathways

3) The CNS is hierarchically organized, with higher centers normally in command of lower centers, which in turn control primitive and more automatic behaviors

4) Recovery from brain damage follows a predictable sequence that mimics the normal development of movement during infancy

5) Primacy of neurophysical explanation (assumes that abnormal movement patterns are the direct result of the neural lesion)

Neurotherapeutic facilitation modl primary aims

-Facilitate normal movement and inhibit abnormal tone and primitive reflexes

-Progress through the developmental sequence

-Usual manual guidance ot correct movement patterns (prevent errors/abnormal movement)

Why would the neurotherapeutic facilitation rehab model lead to dissatisfaction in PT practice?

-Pt becomes reliant on hands-on tx from PT

→Patient needs to experience the challenge/mistakes of achieving the goal (bc this leads to neuroplasticity and problem solving)

Contemporary task-oriented model

-Based on the systems model of motor control

-Target both peripheral and central systems to influence motor control

-Assumes that control of movement is organized around goal-directed functional behaviors

-An evolving base on recent models and research in areas of motor control and motor learning, emerging in the 80s/90s; II STEP, III STEP, IV STEP

In contemporary task-oriented model, training is not limited to “normal” patterns, but allows ….

-patients to learn alternative movement strategies to coordinate motor behaviors as efficiently as possible 

-for active problem-solving and practice in a variety of environmental contexts

-focus on training specificity

Why would PTs who were trained in using Muscle re-education and neuropathic facilitation rehab models express dissastifaction with adopting the contemporary task-oriented rehab model in PT practice

-PT not performing as much direct care, not as immediate feedback

-Traditional PTs may believe that patients shouldn’t be allowed to make errors since the PT is there to ensure it is being done correctly

-Traditional PTs have been using their skills for years and see new grads using new skills as incorrect

What is the position of ANPT regarding traditional rehab models

-Should beb doing HIIT, traditional PTs should move away from traditional tx approaches

-With the old techniques (PNF, NDT, etc.), change the way they were applied through the new systems approach with a functional approach