Motor Control PDF Fall 2024

Motor Control DPT 542 Functional Neuroscience Fall 2024 Anne K. Galgon PT PhD NCS  Objectives Course Objective: Apply the theories of motor development, motor learning and motor control to the observation of normal human movement across...

Motor Control DPT 542 Functional Neuroscience Fall 2024 Anne K. Galgon PT PhD NCS  Objectives Course Objective: Apply the theories of motor development, motor learning and motor control to the observation of normal human movement across the life span P1 Fall Competency 1.1.1a State and describe models of motor control and learning that relate to the human movement systems. Lecture Objectives: Define Motor Control, Motor Learning and Motor Development Create a framework for analyzing the relationships between individual, task and environment constraints on movement patterns. State how motor control theory drives interpretations of motor behavior and guides clinical practice. Primary resource Shumway-Cook, Woollacott: Motor control Chapter 2 Importance: APTA Physical Therapy Identity The physical therapy profession promotes the movement system as the foundation for optimizing movement to improve the health of society. The movement system is the integration of body systems that generate and maintain movement at all levels of bodily function. Human movement is a complex behavior within a specific context, and is influenced by social, environmental, and personal factors.  Importance: Physical Therapists Considered Movement Experts (Movement Scientists) Retrain patients with motor control problems Provide therapeutic interventions to change movement or increase capacity to move Optimize Movement  Motor Control, Motor Development, and Motor Learning Assumptions All of these processes – motor control, motor development and motor learning are mediated in part, by the nervous system By analyzing motor behavior we are indirectly studying brain function Motor Control Processes by which posture and movement are organized, produced, and regulated. Motor Control Defined “as the ability to regulate or direct the mechanisms essential to movement.” How does the CNS organize the individual muscles and joints into coordinated functional movements? Action system How is sensory information from the environment and the body used to select and control movement? Perception System Goal directed movement within the environment Cognitive System utilizing action and perception Motor Learning Learning: as the process of acquiring knowledge about the world. Motor learning: a set of processes Acquiring the capability for skilled action Results from experience or practice Not measured directly, but inferred from behavior Produces relatively permanent changes in behavior (Schmidt & Lee, 2005) Broadening definition: motor learning emerges from complex processing of perception/cognition/and action systems (See SC&W pp 22) Motor Development (Spring course: Movement Science Across the life span) Emergence of posture, movement and development of skills in mobility and manipulation. Time Scales of Interest Motor Motor Development learning Time Motor Control Components of Motor Control Postural Control Movement Control Mobility Manipulation: UE reach grasp and Manipulation Posture and Movement Opposite ends of a continuum Posture – holding a body configuration Standing, sitting, kneeling Movement – changing or transitioning from one posture to another (i.e., discrete task) Standing up, lying down, from one location to another (i.e., continuous task) walking, running manipulating the environment Posture and Movement Posture Movement Base of Support (BoS) is stable BoS is changing Static Dynamic Sustained Changing Stability Mobility Tonic = Long duration Phasic = Short duration Associated with extensor muscles Associated with flexor muscles Isometric (hold) Isotonic (move) Motor Control Involves controlling both posture and movement The relationship between posture and movement is complex What has to be control when you are picking up and drinking a cup of coffee? Theory and Practice Contemporary Practical Perspective Task-Oriented Approach to Movement Analysis Integration of Theories Historical to current evolution Theories are not mutually exclusive The nature of movement Movement emerges as interaction of three factors Individual (person) Task Environment Observed movement results from the individuals capacity to interact with the demands of a task and the demands of the environment Nature of Movement Movement emerges as interaction of three factors Individual (person) (Shumway-Cook, & Woollacott,2012) Task Environment Movement (strategy) Task Observed movement results from the individuals capacity to interact with the demands of a task and the demands of Environment the environment Individual  Use the figure below to problems solve how you could practice transfers with your patient who has poor force production in his lower extremities and reduced anticipatory balance control in sitting. As a result he is not getting his weight forward to initiate sit to stand and needs assistance to stand. This prevents him from get out of the chair safely. His goal is supervision with sit to stand. Next to each element list ways to alter each element that would enhance this patient’s performance. _________________ _________________ _________________ Movement Task ________________ Individual Environment ________________ ________________ ________________ ________________ ________________ https://youtu.be/O0Js2zfQrTM Nature of Movement (Shumway-Cook & Woollacott, 2007) Figure 1.2 SC & W This was discussed on first day of class Individual factors that constrain movement Individual Cognitive Perception Action Action Controlling the movement output Motor components of the nervous system, the body effectors or muscles, characteristics of body parts (joints)that is going to be moved. The coordination of joint movements to produce functional movement The CNS must chose solutions to control the multiple joints and muscles, “degrees of freedom” (Bernstein, 1967) Perception Integration of sensory impressions into psychological meaningful information Peripheral sensory system and central processing for interpretation and meaning Sensory/perceptual system provides information about the state of the body the features in the environment that might regulate movement Cognition Purposeful movement requires intent Includes Attention Planning Problem solving Motivation Emotion All necessary to establish intent or goal of movement.  Task constraints on movement What are the demands of the task? Functional categories of tasks? Mobility (Gentile, 1987) Are there neural mechanisms Stability Manipulation for these categories? Task Stability Tasks were the base of support (BOS) is still BOS = area of body that is in contact with the support surface Sitting Standing Stability tasks in isolation often considered to require less attentional demand often practiced before mobility tasks or manipulation Mobility Moving base of support (BOS) Walking Running Increase attentional demands Quasi-mobile (or Transitional movements) Discrete movements between two different BOS Rolling in bed Sit to stand Manipulation Extremities are moving or controlling objects in the environment Pick up a cup of coffee Kicking a ball Carrying a tray Further increasing attentional demand on stability and/or mobility Environmental Constraints Regulatory Non Regulatory Environmental Constraints on Movement Regulatory features Features in the environment shape movement patterns (Gordon, 1987) Height of the chair Shape or size of the object Movements must conform to the environment to be successful Non regulatory features Features in the environment that movement does not need to conform to (Gordon, 1987) Color of the ball Noise in the room Light in a room Non-regulatory features may or may not effect movement Task and Environment Variability Open movement tasks: Tasks fall on a continuum Variability Task changes between each execution Environment is unpredictable Closed movement tasks No variability between each execution Environment is predictable Classification scheme for different types of Movement tasks (SC&W p5) Category of Tasks Distinguishing Attribute Discrete versus Continuous Discrete: recognized beginning and end: Kicking a ball, sit to stand Continuous: repeated cycle of movement where start and end point decided arbitrarily by performer: Walking & running Closed or Open Closed: relatively fixed and predictable environment. Sitting in a room nothing moving or changing. Open: constantly changing or unpredictable environment. Soccer or tennis Stability vs Mobility Stability: non- moving BOS Sitting and standing Mobility: moving BOS; Walking or running Manipulation versus Non: Manipulation: movement of upper extremities to change the environment. manipulation Shumway-Cook & Woollacott pp. 6 Attentional Demands increase across the Close to Open task Continua Theories of Motor Control (also motor learning) Reflex Theory Hierarchical Theory Motor Programming Theory System Theory Dynamic Systems Theory Ecological Theory Task oriented approach (Shumway-Cook & Woollacott)  What do theories provide? Theories reflect different opinions of relative importance of components of movement Value of theory in practice A framework for interpreting behavior A guide for clinical action Development of new ideas Working hypothesis for examination and intervention Parallel development of motor control Theories and Rehabilitation models  Reflex Theory Charles Sherrington: Neurophysiologist The Integrative Action of the Nervous System 1906 The reflex is the basic building block of movement Complex movement is combined action of a chain of reflexes. Stimulus Response Stimulus Response Stimulus Response Limitations in Reflex Theory Does not explain: All voluntary movement (because a reflex is initiated by an external agent) movement that is predicative or occurs in the absence of sensory information movement that occurs faster than sensory response how same stimulus may result in variable responses ability to produce novel movement Control Hierarchy What is a hierarchy? An organizational structure of a system Each element of the system is subordinate to a single element The root source of control directs subordinate elements without subordination to any other element in the system (i.e., “the king”) Concepts related to Hierarchies Unidirectional flow of information Compartmentalization of function Properties of the hierarchy are attributable to the elements of the hierarchy Control and command is vested in one element Graphic Representation of Control Hierarchy Root Source of Control Subordinate Subordinate Subordinate Element Element Element Subordinate Subordinate Subordinate Subordinate Subordinate Subordinate Element Element Element Element Element Element  Cortex Sub- Cortical Areas Midbrain Brainstem Spinal Cord Is the brain organizational Hierarchical? Dedicated Function in Motor Control Hierarchy Cortex Volitional control is the source of deliberative Voluntary Control actions and learned skills Mid-Brain – Sub-cortical Areas Righting reactions allow normal alignment Righting Reactions with respect to gravity and visual environment Brainstem Tonic reflexes support posture Tonic Reflexes Spinal Cord Phasic reflexes support limb Phasic Reflexes movement  Major Descending Influences on Lower Motor Neurons Motor areas of cortex Corticobulbar Tract Brain stem Corticospinal Tract Rubrospinal tract Reticulospinal tract Vestibulospinal tract Spinal Cord - Lower motor neurons, reflexes, and central pattern generators What is the model that the creator of this diagram is assuming? Hierarchical Model of Motor Control Compartmentalization of Function Who’s in charge? Cortex Voluntary Control Mid-Brain – Sub-cortical Areas Righting Reactions Brainstem Tonic Reflexes Spinal Cord Phasic Reflexes Clinical Implications of Hierarchical/Reflex Theory Clinical testing of reflexes should allow a therapist to predict function Movement behaviors are interpreted in terms of presences or absence of control on reflexes Retraining motor control of functional skills focuses on enhancing or reducing the effects of reflexes during motor tasks Functional training will enhance ability for higher centers to regain motor control Effect of lesion removing Spinal Cord from Higher Center Control Cortex Loss of Higher Center Control Midbrain Sub- What remains? Cortical Areas How many different movement patterns? Lesion removing What kinds of coordination? influence of brain Brainstem stem, Could the patient walk? midbrain and cortex What about balance abilities? Spinal Cord Effect of Removing Cortical Influence Cortex Loss of Higher Centers Midbrain Sub-Cortical What remains? Lesion removing Areas influence of How variable will movement patterns Cortex be? What about “balance”? Brainstem What about volitional control? Spinal Cord Limitations Can not explain the dominance of certain reflexive behaviors in certain situations in adults. (bottom up control) How does the sensory information influence movement? Who is in charge? Think about how automatic behaviors are stored and controlled.  Motor Program Theory The motor system is reactive, but is not stereotypic as in reflexes When the stimulus is removed movement still occurs Central motor patterns or motor programs Are more flexible than a reflexes Complex movement dynamics are stored and activated for specific tasks Examples: Central Pattern Generators (neural substrate) Writing your signature (stored rules of a movement pattern) Central Pattern Generator A neural substrate for generating movement https://oxfordre.com/neuroscience/view/10.1093/acrefore/9 780190264086.001.0001/acrefore-9780190264086-e-55 Motor Program Theory Several motor learning theories: development of motor patterns or programs Adams close loop motor control theory Schmidt’s Schema Theory or generalized motor program theory. Motor program and feedback interaction to change and develop rules for movements.  Motor Program Theory Memory The capacity to store and retrieve information Schema - a memory structure a memory structure that can be used to interpret new situations Developed as a result of “learning” and repeated exposure to the “class of objects” or experiences that make up a schema  Schmidt’s Schema Theory SC&W Ch2 Schema – a memory structure that is a rule Schmidt proposed that a motor program is a memory structure with Invariant features that don’t change Parameters that are adjusted according to the specific situation in which the individual must perform (e.g. regulatory features in the environment) Schmidt’s Schema Theory Four items Initial movement conditions (body position, weight of object) Parameters used in the generalized motor program Force, muscle activation etc Knowledge of results (KR)(Success) Sensory consequences of how it felt/looked Schmidt’s Schema Theory Two memory structures Recall schema  The relationship between parameters assigned to a motor program and the outcome it produces  Recall memory – responsible for production of movement Recognition schema  The relationship between initial conditions, outcomes and sensory consequences  Recognition memory – responsible for movement evaluation Sensorimotor Cortex Error Signal Desired Corticospinal State Cerebellum UMN Corticopontine LMN to muscle KR Intrinsic feedback Sensory Proprioception  Clinical Implications of Motor Programs Move away from reflexes as source of movements Help define normal and abnormal movement patterns Motor Programs are learned through experience Movement patterns are defined more by the task Classes of programs, e.g. throwing, kicking. walking Interventions to help learn the rules of movement patterns or programs. Interventions focused on retraining patterns of movement, not just on specific muscles in isolation. Limitations: Motor program theory Motor program cannot be the determinant of all movements Limited capacity to store all movements Similar movement command would change depending on the initial joint conditions Does not completely account for how the CNS manages variability of the musculoskeletal system and environment Systems Theories Many theories could be classified under a systems approach. Each theory may emphasize something more. Schema (motor program) Theory* (not excluded from systems perspective) Systems (Bernstein) Dynamic Action Systems Dynamic Systems Theory Ecological Systems Task Oriented Approach  Systems Theory Concepts 1. Reciprocity – Reciprocal Connections within a network of interneurons feedback loops sharing information among interneurons the concept of levels becomes meaningless 2. Distributed and Shared function Functions are distributed among neurons throughout the system Neurons may take on different roles depending on situation Systems Concepts 3. Emergent Properties – network properties reflect the interaction among interneurons Neurons may have multiple purposes or contribute to multiple movement functions. Command appears to be an emergent property Control/command comes about through consensus Emergent Properties also account for other systems (includes the musculoskeletal, cardiopulmonary, integumentary properties) and the interaction with the environment.  Advantages Command Flexibility Command can be transferred to networks that have unique and important information related to the motor behavior Allow for movement to outlast a command or stimulus (e.g. CPG) Redundancy Shared and distributed function Less susceptible to loss of critical elements from injury or developmental abnormality Protects against loss of function Bernstein’s Theory Fundamental Assumption: The body is a mechanical system subject to physical laws A neural command can have different effects depending upon initial conditions of the body for example, “Stand up!” movements will vary depending on start position – supine, prone, sitting, etc. Mechanical System The Degrees of Freedom Problem The skeletal system has approximately 148 movable bones 244 Degrees of freedom (Zatsiorsky, 1998) How are these degrees of freedom controlled?  Movement Solutions Synergies Coupling of degrees of freedom by constraining muscles to act as a unit Provide a “manageable” repertoire of movements Shumway Cook & Woollacott propose Muscles = letters Synergies = words Actions = sentences Movement patterns that may appear in conjunction with sensory stimuli or independent of those stimuli Contributions of Bernstein Reminder that the body is a mechanical system with muscles and bones subject to laws of physics Limitations of Bernstein Not as focused on environmental contributions to motor control Dynamical Action Theory Another Systems Theory Provides explanations for 2 problems 1. How do patterns and organization seen in the natural world come to be? 2. How do these patterns and organizations change over time?  1. How do patterns and organization seen in the natural world come to be? ◼ Principle of Self Organization When individual parts come together they behave in an ordered way Higher center control is not needed Coordinated movement emerges as a result of interacting elements of the system neural networks, a body that is essentially a mechanical system, and the capacity to establish synapses within the nervous system  2. How does the system change? ◼Non-linear properties of the system lead to new organizational structures Simplest example walking on treadmill Increase speed → running pattern emerges Running is not fast walking – a very different synergy Dynamical Systems Theory (DST) Related to Dynamical Action Theory DST uses principles of Thermodynamics to explain transitions from one movement state to another Dynamic Systems Open Systems Closed Systems free exchange of energy from limited exchange of energy the outside from the outside living systems are “open”... exchanging food, air, etc. an atom is a relatively closed system information is also considered a form of “energy” that may be no system is completely exchanged closed Dynamic Systems Theory Kugler, Kelso, Turvey, et al. The motor system is an open system Applies principles from philosophy, biology, engineering science and physics, especially thermodynamics Behavior based on the interaction between the individual and the environment. Movement patterns can be described as stable and unstable states Terminology Related to Non-linear Transformations Control Parameter The variable in a system that can be scaled to produce change in the system change from one stable movement pattern to another for example, in the walking to running example, the control parameter is velocity Body weight in children Ankle ROM in walking gait pattern Value of using Control Parameters Provides therapists with a way to think about how to alter habitual movements What can be scaled (changed) to produce a different movement pattern? Terminology Related to Non-linear Transformations Attractor States A preferred movement pattern used to perform a functional skill Individuals display variability in movement patterns during functional tasks- Rolling, coming to standing, getting out of bed But preferred or consistent patterns could be considered an attractor state Attractor States Deep Well Shallow Well Stable Unstable or Variable Hard to Change or Perturb Easy to Change or Perturb Important Concepts of Systems Theories (discussed so far) The biomechanical elements of the system are important (Bernstein) Coordination patterns are motor solutions to managing forces Principle of Self Organization Non-linear properties of organization Control Parameter Attractor States Stable and Unstable movement patterns Ecological Theory or Perceptual Action Theory (Gibson) Another Systems Theory How do we use perception to control movement? 1st motor control theory to examine how environments shape behavior Ecological -Perception Action Theory Actions require perceptions specific to the task Actions are organized for a task performed in a specific environment How does the individual detect information relevant to the task?  Perception Action Theory Terminology Constraints – the boundaries that limit ones actions (strength, flexibility, balance, etc) Affordances – the perception that captures interaction between an individual and the environment in which a task is to be performed What environmental object is “sit on able”? How will I climb these stairs? Adult or small child What are the environmental differences that change movement? https://depositphotos.com/stock-photos/picking-up-coffee.html https://www.123rf.com/stock-photo/sunday_coffee.html Clinical Implications The individual is an active explorer of the environment Active Exploration of the task and the environment results in multiple solutions Adaptability: flexibility of motor solutions and improved perception. Interventions: promote exploration and adaptability of motor solutions Nature of Movement (Shumway-Cook, & Woollacott,2012) Movement (strategy) Task Individual Environment  Summary Defined Motor control, learning and development Discussed a contemporary model of examining and treating movement (Task Oriented approach) Reviewed Motor Control Theories (Historical Perspective) Identify terminology unique to these theories was presented Discussed clinical utility and limitations of Theories Next lecture: Neuro Neural Contributions to Motor Control of UE reach, grasp and manipulation. Chapter 17.