BPK 207 - Sensorimotor Control and Learning PDF

1/7/2025 The real reason for brains Daniel Wolpert 1 https://www.ted.com/talks/dan...

1/7/2025 The real reason for brains Daniel Wolpert 1 https://www.ted.com/talks/daniel_wolpert_the_real_reason_for_brains 1 Image: https://www.nih.gov/news-events/nih-research-matters/new-insights-into-brain-s-motor-cortex Gordon EM, et al. A somato-cognitive action network alternates with effector regions in motor cortex. Nature, 2023. 2 2 BPK 207 – Sensorimotor Control and Learning Section #1 – Motor Control Introduction 3 3 1  1/7/2025 Section Learning Outcomes By the end of this section, you will be able to… – Describe three motor control problems that the nervous system deals with to control movement (motor learning problem will be covered in section 8) – Identify fundamental features governing the control of standing, walking, reaching, and eye movements – Define and distinguish the factors that affect movement – Classify motor behaviour 4 4 Section #1 – Motor Control Introduction 2 SENSORIMOTOR CONTROL INCLUDES Section 1: Sensorimotor Control Introduction 3 RELEVANT DEFINITIONS Learning Outcomes: Define key concepts and classify motor behaviors. 4 HOW IS MOTOR BEHAVIOUR CONTROLLED? Sensorimotor Control: How sensory info, the 5 SENSORIMOTOR CONTROL PROBLEMS: nervous system, and various factors influence 5.1 Degrees-of-freedom (DOF) problem movement, adaptation, and recovery from injury. 5.2 Serial-order problem 5.3 Sensorimotor integration problem Definitions: Distinguish between motor behavior, 5.4 Motor learning problem skills, and movements. Control Mechanisms: Feedforward and feedback 6 FUNDAMENTAL PRINCIPLES OF DIFFERENT ACTIONS: control in movement. 6.1 Standing balance 6.1a Anticipatory postural adjustments (APAs) Control Problems: Degrees of freedom, serial 6.2 Walking order, sensorimotor integration, and motor learning 6.3 Reaching and grasping challenges. 6.4 Gaze Behaviour Fundamental Actions: Overview of standing, 7 MOTOR BEHAVIOUR FRAMEWORK walking, reaching, and gaze. 7.1 Environmental features 7.2 Task constraints Behavioral Framework: Analyzing motor behavior by considering environment, task, and individual 7.3 The individual factors. 8 CLASSIFYING MOTOR BEHAVIOUR Motor Behavior Classification: Categorizing movements as reflexive, rhythmic, or voluntary; and 9 BODY MOVEMENTS – NOMENCLATURE by musculature, movement type, and environment. 5 5 2,3. Important Definitions Motor behaviour – Includes individual movements and motor skills Motor skill – A goal-directed task that requires voluntary head, body, and/or limb movement – Made up of a series of movements – Example: shooting a basketball into a hoop Movement – Is a component of a motor skill and is defined by the behavioural characteristics of the limb or a combination of limbs 6 6 2  1/7/2025 2,3. Why Distinguish Movements from Skills? People learn movements when beginning to learn a skill – Different movements can produce the same skill People adapt movement characteristics to achieve the same goal Motor skills and movement are measured differently – Skills = relate to outcome – Movements = relate to specific characteristics (e.g., kinematics, EMG) 7 7 4. How is motor behaviour controlled? Motor behaviour is a combination of feedforward and feedback control – Feedforward control: Uses sensory information prior to the execution of movement rather than during the movement – Feedback control: Uses sensory information (“sensory feedback”) during the execution of movement – Optimal control of motor behaviour requires a combination of feedforward and feedback processes 8 8 5. Sensorimotor Control Problems The nervous system must deal with several problems in order to control movement – However, these problems are not ‘bad’; and the nervous system is quite capable of dealing with all of them 5.1. Degrees of freedom (DOF) problem 5.2. Serial-order problem 5.3. Sensorimotor integration problem 5.4. Motor learning problem (Section 8) 9 9 3  1/7/2025 Challenges in Robot Motion Control: Understanding the Nervous System's Solutions 9 years ago https://www.youtube.com/watch?v=g0TaYhjpOfo 10 10 Challenges in Robot Motion Control: Understanding the Nervous System's Solutions Now – Boston Dynamics https://www.youtube.com/watch?v=-e1_QhJ1EhQ&ab_channel=BostonDynamics 11 11 Challenges in Robot Motion Control: Understanding the Nervous System's Solutions Now – Tesla (Optimus) https://www.youtube.com/watch?v=cpraXaw7dyc&ab_channel=Tesla 12 12 4  1/7/2025 Challenges in Robot Motion Control: Understanding the Nervous System's Solutions (yes!!!) Now – Tesla (Optimus) https://www.youtube.com/watch?v=cpraXaw7dyc&ab_channel=Tesla 13 13 5.1. Degrees of Freedom Problem DOF refers to all the independent variables in a system (which in this case is one’s body) – This makes control complex, but having many DOF is also an advantage, as it provides greater flexibility Solutions to the DOF problem: – Efficiency: avoid extreme joint angles; move smoothly – Synergies: “freeze out” a portion of the DOF and introduce temporary, rigid couplings between multiple DOF (thus reducing the DOF) Note: CNS may not need to reduce DOF per se; rather it may need to identify which DOFs are task-relevant and thus control – Exploit the mechanics of the joints and muscles. E.g., inertia, gravity 14 14 5.2. Serial-order Problem Nervous system must sequence a movement or series of movements Solutions to the serial order problem: – Creating a plan (i.e. Motor plan) To create a smooth movement, the nervous system sequences muscle activations in the correct order by forming a motor plan. This involves several brain regions (discussed in Section 5: Motor Systems and Action). – Co-articulation The strategy of co-articulation is used, where simultaneous motions of different body parts help achieve tasks over extended periods, ensuring one muscle's activity starts before another ends. 15 15 5  1/7/2025 5.3. Sensorimotor Integration Problem T = Target position H = Hand position Also called the “Perceptual-motor M = Motor error Integration Problem” B = Body coordinates E = Eye-centered coordinates Need to integrate sensory information (from a variety of sources) to form a perception, which it can then use to act on One of the major issues related to this problem is that sensory information is encoded by different receptors in different parts of the body Spatial Co-ordination – Which spatial co-ordinate system is used? Buneo CA, Andersen RA. The posterior parietal cortex: sensorimotor interface for the planning and online control of visually guided movements. Neuropsychologia. 2006;44(13):2594-606. doi: 10.1016/j.neuropsychologia.2005.10.011. Epub 2005 Nov 21. PMID: 16300804. 4. Motor learning problem (Section 8) 16 16 6. Fundamental principles of different actions 6.1. Standing 6.2. Walking 6.3. Reach and Grasping 6.4. Eye Movement 17 17 6.1. Standing: Balance Goal is to remain upright – Work against gravity – Control balance despite breathing – Utilizes multiple sensory systems Normally characterized by a small amount of postural sway Affected by a number of factors (Tresilian 2012) – Physical characteristics and condition of the individual – Stance posture – Support surface characteristics – Availability of sensory information – Psychological factors 18 18 6  1/7/2025 6.1. Standing: Postural Stability Centre of mass (CoM) is the point that is at the centre of the total body mass Base of support (BoS) is the area of the body that is in contact with the support surface Alberto Giacometti, L’homme qui chavire, 19 1950 19 6.1. Standing: Relationship Between COM, COP and BOS 20 20 6.1. Standing: Relationship Between COM, COP and BOS 21 21 7  1/7/2025 6.1a. Standing: Anticipatory Postural Adjustments (APAs) APAs are the postural changes (caused by changes in muscle activation) that occur prior to (or at the same time as) the onset of the postural disturbance due to self- movement – APAs are meant to minimize the potential disturbance that the movement may cause What is the purpose of an APA? To maintain equilibrium (postural stability) Stabilize the position of relevant body segments 22 22 6.1a. Standing: Anticipatory Postural Control: APAs Kandel et al. 2000 Posterior view Marker (body part) trajectories Black dots = motion tracking markers Behavior = raise right Start leg to side (abduction) Time COG = COM for our purposes (Centre for gravity = centre of mass) 23 23 6.2. Walking Goal-directed walking utilizes multiple sensory systems and relies heavily on spinal cord integration with modifications from descending brain commands Consists of stance phase and swing phase Foot placement is essential – Majority of falls occur during walking – Walking is essentially a series of controlled falls Must keep centre of mass (COM) inside a constantly moving base of support (BOS) – Must control large head, arms, and trunk mass from moving too much 24 24 8  1/7/2025 6.2. Walking: Step Cycle Inman et al. 1981 25 Tresilian 2012 25 6.3. Reaching and Grasping What is important? – Location of target – Characteristics of target Size, shape, mass, texture, compliance – Initial arm/shoulder configuration 26 26 6.3. Reaching and Grasping Three components: – Transport of hand to the spatial location of object – Orientation of the hand to align it with the spatial orientation of the object – Preshaping of the configuration of the digits and thumb in preparation to grasp the object The kinematics of these components are highly coordinated Gosselin-Kessiby et al. 27 2008 27 9  1/7/2025 6.3. Reaching and Grasping 3 Characteristics of reaching: Characteristics of grasping: – Straight-line hand paths to targets – Progressive opening of the grip with straightening of the fingers followed – Unimodal, smooth, bell-shaped by gradual closure velocity profile of the hand – Max. grip aperture – Peak velocity and peak acceleration Point in time which the thumb-finger scale with movement amplitude opening is the largest (60-70% of duration of reach) 28 Scott 2004 Castiello 2005 28 6.4. Eye movements: Importance of Gaze Behaviour Central 5° of visual field has the greatest # of cones and best spatial resolution High visual acuity information is available from less than 1% of the surrounding environment Eye and/or head movements (i.e., gaze behaviour) are used to visually sample the environment Gaze shifts = change in direction of the line of sight relative to a fixed, external reference – Measured by eye tracker Land 2006 29 29 6.4. Eye movements: Saccadic & Smooth Pursuit Figures from: Kandel et al. 2013 Systems Saccade = to move the eyes as quickly as possible to shift the fovea to a visual target in the periphery – Occur up to 800°/s – Too fast for sensory feedback to be used during the movement Smooth pursuit = keeps the image of a moving target on the fovea – Max. velocity up to 100°/s Saccade trace is clipped actually 10-50x faster Six extraocular muscles: These muscles move the eye in different directions, including up, down, side to side, and rotation 30 https://www.youtube.com/watch?v=Rm-RAN7ewkQ&ab_channel=Dr.FatihAd%C4%B1belli 30 10  1/7/2025 6.4. Eye movements: Eye-head Coordination When beginning in the central orbital position, the largest eye movements are no greater than about 40-45° in either horizontal direction – This is essentially the neuromechanical limit To extend these limits without moving the body, head movements can accompany eye movements – This complicates the neural control, as eye and head movements must be controlled together Freedman 2008 31 31 6.4. Eye movements: Eye-head Coordination 32 32 6.4. Eye Movements & Eye Trackers Yarbus 1967 Marigold and Patla 33 2007 33 11  1/7/2025 6.4. Eye Movements & Eye Trackers https://www.youtube.com/watch?v=3OdkHo3ThAE&ab_channel=PupilLabs 34 34 Eye Movements & Eye Trackers Limb movement tracking Tracking tasks are common and often used in laboratory Person moves a device to track a path via certain limb movements – Pursuit tracking Experimenter-produced actions of the target and subject’s own movements are both displayed E.g., two cursors on a computer screen are displayed, one controlled by the experimenter and the other by the subject Real-life application – E.g., Eyes track (or pursue) a moving object 35 35 Eye Movements & Eye Trackers Limb movement tracking 2 Compensatory tracking – Experimenter-produced variations in the track are combined with subject’s movements to produce a single target value on a screen Subject must maintain this target value at some location 1 – E.g., One cursor on the screen that is controlled by experimenter and subject The subject is required to move the cursor from point 1 to point 2. However, the experimenter introduces an artificial motion that shifts the cursor from point 1 to point B. To – E.g., Aircraft instruments; human- ensure the cursor moves in a straight line from point 1 to computer interfaces, force field (limb point 2, the subject must compensate for this induced motion. For instance, this can be achieved by moving in the movements) opposite direction, from point 1 to point A. Step tracking – Path or target ‘jumps’ from one location to another (usually unpredictably) – Subject must correct and move to the new location – E.g., Often used to study eye movements 36 36 12  1/7/2025 7. Motor behaviour framework ***A critical framework for this course*** 37 37 7. Movements / Motor Skills Emerge from the Interaction of 3 Factors Movement is generated to meet the demands of the task being performed within a specific environment – Organization of movement is constrained by factors associated with or within the: Environment Task Individual ***A critical framework for this course*** 38 Based on: Shumway-Cook & Woollacott 2007 38 7. Factors that Constrain Movements / Motor Skills Based, in part, on: Shumway-Cook & Woollacott 2007 Terrain Weather conditions Ambient lighting Interact or avoid objects? Objects (size, shape, speed) If yes: Grasping/manipulating? Attention Carrying it? Motivation Hitting it Emotional aspects Intercepting it? How much force? Motor-related: Brain regions that allow for movement Base of Support (BoS): Sensory-related: Coordination of many muscles (stationary BoS) Sitting, standing Integration of sensory input and joints (DOF problem) (moving BoS) Walking - State of individual’s body (e.g. limb position) Accuracy needed, direction, - Environmental features trajectory to follow 39 39 13  1/7/2025 Questions to ask: What is the motor behaviour and the goal? What are the relevant environmental features? Are there objects to interact with or avoid? What sensory information is used or required? What movements are made, and what muscles or body parts (or limbs) are used? Are multiple behaviours being performed? Are there distractions? 40 40 7.1. Environmental Features What are the relevant environmental features that affect the movement(s) or motor skill? Examples: – Size, shape, and speed of object(s) – Terrain – Weather conditions – Ambient lighting Recognize that these features must be perceived and may need to be related to the individual or task 41 41 7.2. Task Constraints Object interaction constraints – Do you need to interact with or avoid an object? – If interacting with it, are you: Grasping/manipulating it? Carrying it? Hitting it? Intercepting it? Stability constraints – Stationary base of support E.g., sitting, standing, stance limb during walking – Moving base of support E.g., walking 42 42 14  1/7/2025 7.3. Factors within the Individual Cognition Action Perception Cognitive-related factors Includes attention, motivation, and emotional aspects of motor behaviour For example, whether someone is scared or unmotivated may affect how they perform a task 43 43 7.3. Factors within the Individual Sensory-related factors Integration of sensory input into meaningful information (to form a perception) - Sensory systems provide information about the state of the individual’s body (e.g., limb position) and environmental features (e.g., different terrain) - What is the limb’s position at a given moment? Which direction do I need to move and what is the specific trajectory to follow? 44 44 7.3. Factors within the Individual Motor-related factors There are specific motor systems (brain regions, descending tracts) that allow for movement Many muscles and joints must be coordinated Recall the degrees-of-freedom problem (Section 1.5.1) With what accuracy should I move? Which direction do I need to move and what is the specific trajectory to follow? 45 45 15  1/7/2025 8. Classifying motor behavior Organization of Movement – Three Categories Reflexive – Involuntary coordinated stereotyped patterns of muscle contraction and relaxation elicited by peripheral stimuli (e.g., stretch reflex) Rhythmic – Repetitive, can occur spontaneously or triggered by peripheral stimuli (e.g., chewing, swallowing, scratching) Voluntary – Goal-directed movements that improve with practice as a result of feedback and feedforward mechanisms 46 46 8. Classifying motor behavior 3 one-dimensional classification systems 3 one-dimensional classification systems (Magill 2007) – Size of primary musculature required Gross versus fine motor skills – Specificity of where movements of skill begin and end Continuous versus discrete motor skills – Stability of the environmental context Open versus closed motor skills – Closed: environment predictable, ex. Picking up a cup – Open: environment unpredictable, ex. Catching a butterfly 47 47 8. Classifying motor behavior 3 one-dimensional classification systems 1. Size of Primary Musculature Magill 2007 48 48 16  1/7/2025 8. Classifying motor behavior 3 one-dimensional classification systems 2. Specificity of Start and End Tasks (or motor behaviours) can be discrete, continuous, or serial – Discrete tasks have a recognizable start and end E.g., kicking a ball, sit-to-stand – Continuous tasks have an end point not inherent in the task but individually defined E.g., walking – Serial tasks are made up of a series of individual movements 49 49 8. Classifying motor behavior 3 one-dimensional classification systems 2. Specificity of Start and End Schmidt and Lee 2005 Discrete tasks have a recognizable start and end. Ex. kicking a ball, sit-to-stand. Continuous tasks have an end point not inherent in the task but individually defined. Ex. Walking 1 km. Serial tasks are made up of a series of individual movements. Ex. Walk one step and throwing a ball. 50 50 8. Classifying motor behavior 3 one-dimensional classification systems 3. Stability of the Environment Picking up a cup Walking on a crowded sidewalk 51 Schmidt and Lee 2005 51 17  1/7/2025 9. Body movements – nomenclature 52 Section #1 – Motor Control Introduction 2 SENSORIMOTOR CONTROL INCLUDES Section 1: Sensorimotor Control Introduction 3 RELEVANT DEFINITIONS Learning Outcomes: Define key concepts and classify motor behaviors. 4 HOW IS MOTOR BEHAVIOUR CONTROLLED? Sensorimotor Control: How sensory info, the 5 SENSORIMOTOR CONTROL PROBLEMS: nervous system, and various factors influence 5.1 Degrees-of-freedom (DOF) problem movement, adaptation, and recovery from injury. 5.2 Serial-order problem 5.3 Sensorimotor integration problem Definitions: Distinguish between motor behavior, 5.4 Motor learning problem skills, and movements. Control Mechanisms: Feedforward and feedback 6 FUNDAMENTAL PRINCIPLES OF DIFFERENT ACTIONS: control in movement. 6.1 Standing balance 6.1a Anticipatory postural adjustments (APAs) Control Problems: Degrees of freedom, serial 6.2 Walking order, sensorimotor integration, and motor learning 6.3 Reaching and grasping challenges. 6.4 Gaze Behaviour Fundamental Actions: Overview of standing, 7 MOTOR BEHAVIOUR FRAMEWORK walking, reaching, and gaze. 7.1 Environmental features 7.2 Task constraints Behavioral Framework: Analyzing motor behavior by considering environment, task, and individual 7.3 The individual factors. 8 CLASSIFYING MOTOR BEHAVIOUR Motor Behavior Classification: Categorizing movements as reflexive, rhythmic, or voluntary; and 9 BODY MOVEMENTS – NOMENCLATURE by musculature, movement type, and environment. 53 53 References (and Sources) Castiello U. The neuroscience of grasping. Nature Reviews Neuroscience 6: 726-736, 2005. Freedman EG. Coordination of the eyes and head during visual orienting. Exp Brain Res 190: 369-387, 2008. Gosselin-Kessiby N, Messier J, Kalaska JF. Evidence for automatic on-line adjustments of hand orientation during natural reaching movements to stationary targets. J Neurophysiol 99: 1653-1671, 2008. Inman VT, Ralston HJ, Todd F. Human walking. Baltimore: Williams & Wilkins, 1981. Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA, Hudspeth AJ. Principles of Neural Science, 5th Edition. New York: McGraw-Hill, 2013. Land MF. Eye movements and the control of actions in everyday life. Prog Retinal Eye Res 25: 296-324, 2006. Magill RA. Motor learning and control: concepts and applications. 8th Edition. Boston, MA: McGraw-Hill, 2007. Marigold DS, Patla AE. Gaze fixation patterns for negotiating complex ground terrain. Neuroscience 144: 302-313, 2007. Rosenbaum DA. Human motor control. San Diego: Academic Press, Inc., 1991. Schmidt RA, Lee TD. Motor Control and Learning: A Behavioral Emphasis. 4th Edition. Champaign, Ill: Human Kinetics Publishers, 2005. Scott SH. Optimal feedback control and the neural basis of volitional motor control. Nat Rev Neurosci 5: 1-14, 2004. Shumway-Cook A, Woollacott MH. Motor control: translating research into clinical practice. 3rd Edition. Philadelphia, PA: Lippincott Williams & Wilkins, 2007. Tresilian J. Sensorimotor control and learning. An Introduction to the Behavioral Neuroscience of Action. Palgrave Macmillan, 2012. Yarbus A (1967) Eye movements and vision. New York: Plenum Press. 54 54 18