KIN 3513 The Classification of motor skills Motor Control/Learning/Development • Motor Control – Is about functions – The coordination and activation of muscular, skeletal, and neurological functions to produce movements. • Motor Learning – Is about changes – The process of changes due to practice or exIf you want to learn more check out gogkg
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perience leading to improvements in motor skills in terms of accuracy, speed, and movement smoothness. • Motor Development – Is about age related changes and functions – Human developmental issues related to either Motor Control or Motor Learning. Why Classify Motor Skills? • It provides you with a basis for establishing generalizations or principles about how we learn motor skills • Enables you to develop theories about skill performance and learning • Establishes guidelines for instructors, coaches, therapists about how to develop effective strategies to enhance motor skill learning What is a motor skill? • Characteristics: – Action goal: it has a purpose – Performed voluntarily – Requires movement of body, head, and/or limb(s) to achieve the action goal Action versus movements • Actions – Goal-directed activities that involve body, head and/or limb movements • Examples – Walking – Throwing – Catching • Measures – Distance – Time • Movements – What body, head and/or limb segments do when an action is performed • Can vary across performance and/or individuals for the same action • Measures – Kinematics – Kinetics 1Movements • Movements are the component parts • Can vary across actions • A variation of movements can be used to achieve the same action goal Why distinguish actions and movements? • Three reasons: 1. People initially learn actions 2. People adapt movements to achieve the goal of an action 3. Actions and movements are evaluated with different types of measures. The Classification of Motor skills ∙ What are the differences? ∙ What are the similarities? ∙ What factors affect performance? ∙ Classification systems ∙ One- and two-dimensions ∙ Task and Performance perspective One-dimensional systems ∙ Execution oriented o Gross motor skills vs Fine motor skills Gross motor skill: large muscles Fine motor skill: small muscles Continuum of muscle size Large muscles Small muscles Gross motor skills Fine motor skills Do skills require the use of either small or large muscles? ∙ CLICKER: Piano playing is __. o A. Predominantly gross motor skill o B. Predominantly fine motor skill ∙ CLICKER: Running with a prosthesis is __. Prothesis doesn’t matter—still using the same large muscles o A. Predominantly gross motor skill o B. Predominantly fine motor skill ∙ CLICKER: Pitching a baseball is __. o A. Predominantly gross motor skill o B. Predominantly fine motor skill o This is a task that is somewhere in between—the motion is similar to running, but the hand motions are similar to piano playing. ∙ Task organization o Discrete vs. Continuous Discrete: defined beginning and end ex: typing one button at a time Continuous: no defined beginning or end ex: walking to class 2 Serial skill: a group of discrete skills strung together, order is critical ex: picking up a ball and throwing it or typing a word (needs to be in order) Continuum of beginning and ending Specified Serial motor skills Arbitrary Discrete motor skills Continuous motor skills Typically more simple Typically more complex movements movements ∙ CLICKER: What is skating o Discrete o Serial o Continuous ∙ CLICKER: What is turning on the lights? o Discrete o Serial o Continuous ∙ CLICKER: What is shifting gears in a manual car? o Discrete o Serial o Continuous One dimensional ∙ Importance of Motor and Cognitive elements o Motor vs Cognitive Motor: The determinant of success is the quality of the movement/action. Ex: doing a cartwheel Cognitive: The decisions about which movement/action to make are critical. Ex: packing a bag for vacation and making sure everything fits in the bag Continuum of importance of movement quality How to do it What to do Motor skills Cognitive skill ∙ CLICKER: Doing a high jump o 1. More Motor Elements: if you move your body incorrect, the bar will far and will be done incorrectly o 2. Motor and Cognitive Elements o 3. Cognitive Elements ∙ CLICKER: Moving a piece in a chess game o 1. More Motor Elements o 2. Motor and Cognitive Elements 3o 3. Cognitive Elements: you can move it with your toe, mouth, etc, so the motor part is irrelevant—need to focus on where to move it in order to be successful ∙ CLICKER: throwing a football o 1. More Motor Elements o 2. Motor and Cognitive Elements: need to throw it properly and need to throw to the correct person o 3. Cognitive Elements ∙ Stability of the environment o Closed vs Open o Closed: Relevant environmental context features are stable Walking down the hall with no one around o Open: Relevant environmental context features change/are not stable Externally based Walking on a treadmill Walking down the hallway between classes with people in the hall ∙ CLICKER: Bowling is o Closed motor skill: only moving if you want it to move, the pins aren’t moving away; you can decide when you want to throw the ball o Open motor skill ∙ CLICKER: Passing the ball in soccer o Closed motor skill o Open motor skill: when you are passing the ball, you need to adjust that movement in accordance where the person you’re passing to is, etc. ∙ CLICKER: Shooting o Closed motor skill: shooting a stationary object o Open motor skill: shooting a rabbit that is moving around Continuum of environment stability Fixed/stable Change/not stable Closed motor skills Open motor skills Self-paced Externally-paced Environmental context includes: 1. supporting surface 2. objects 3. other people Two-dimensional Taxonomy ∙ Captures more complex skills that practitioners may encounter ∙ Taxonomy – A classification system organized according to relationships among component characteristics of the group of items or objects being classified ∙ Gentile’s two dimensions taxonomy (1987) 4o What is the environmental context in which the person performs the motor skill o What function of the action characterizes the motor skill ∙ Environmental context (First dimension) (has two sub-dimensions) o Regulatory conditions Environmental context characteristics that determine (regulate) movements needed to perform an action Stationary or in motion o Intertrial variability Change in regulatory conditions from one trial to the next when performing the same action Yes or No ∙ CLICKER: Picture of a batter in a batting stance o Regulatory conditions are stationary o Regulatory conditions are in motion: regulatory condition is the ball (in motion) ∙ CLICKER: same picture o No intertrial variability o There is intertrial variability: the pitcher isn’t going to pitch the same exact pitch every time (there would be no variability in a batting cage with a pitching machine that is super accurate and can throw the same exact ball every single time) ∙ CLICKER: combing your hair o Regulatory conditions are stationary: you control the comb, mirror, and the hair will not move o Regulatory conditions are in motion ∙ CLICKER: same picture o No intertrial variability: no matter what the conditions are, you can still start at the same place o There is intertrial variability ∙ Closed Skill: shooting a free throw (no ITV), golf (the holes have ITV) ∙ Open Skill: treadmill with same speed (no ITV), treadmill with different speed (ITV) ∙ Gentile’s two dimensions taxonomy (1987) o Function of the action (Second dimension) Body orientation Location of the body determined by action goal (only x and y—no vertical movements) 5 Body stability = action goal does not involve moving the body from one location to another Body transport = action goal involves moving the body from one location to another (actively or passively) Object manipulation Is an object manipulated as part of the action goal Yes or No. ∙ CLICKER: Batter in batting stance Is there object manipulation? o YES: baseball bat? o NO ∙ CLICKER: Same picture o Body stability (location is maintained): you only can count movements in the x and y direction as movement o Body transport (location is changed) ∙ CLICKER: old man climbing stairs with a cane o An object is manipulated: the cane is manipulated—the railing isn’t manipulated unless he picks the entire thing out of the ground o NO object manipulated ∙ CLICKER: same picture o Body stability o Body transport ∙ CLICKER: Man sitting on a bus in a chair o An object is manipulated o NO object manipulation ∙ CLICKER: same picture o Body stability o Body transport: can occur actively or passively—the man is only the bus for the purpose of transportation and moving o Environmental context Regulatory conditions Intertrial variability o Function of the action Body location change (orientation) Object manipulation o So there is a 2x2 in matrix in each dimension resulting in 16 skill categories. • Each of the 16 skill categories put different demands on the performer • Skill complexity basis for taxonomy organization – Simple (1A) diagonally to most complex (4D) • The task becomes more complex by • Open environment • Trial-to-trial variability • Object manipulation • Body transport Practical uses of Gentile’s Taxonomy • Guide to evaluate motor performance capabilities and limitations 6• Systematic basis for selection of progressions of functionally appropriate activities to overcome deficiencies • Chart person’s progress – develop a profile of competencies Performance proficiency perspective (Guthrie, 1952) Features that distinguish higher-skilled performers from lower skilled ones • Certainty – What is the certainty of goal achievement • Energy – Is the required energy minimized (or conserved) during the action • Movement time – Is the time necessary to perform the action minimized – Has to be looked at if you achieved the goal because it might not be accurate Short refresher of statistical measures The Mean • Arithmetic average of scores in a distribution • The scores need to be at least at least interval-scale • The mean is the central point in a data-set with a normal distribution Standard deviation • Square root of the variance • Variance is the mean of the squared deviations about the mean Between the Mean–SD and Mean+SD lays about 68.2% of the distribution Between the Mean–2xSD and Mean+2xSD lays about 95.4% of the distribution 7The Median • The median is the point on a scale of measurement below which 50% of the scores fall (also called the 50th percentile). • To find the median: – Rank order the measures from low to high – Count the number of measures and add one. – Divide by 2 => the measure at the (N+1)/2-place is the median. – When N is even. The median it is the value halfway the two measures in the middle of the series. (N+1)/2 Correlation CLICKER: graphs on the board and question about correlations 1. High positive 2. Low positive 3. High negative (correlation of .75 or higher means that it is high correlation, .40 and lower is no correlation) Gentile’s two dimensions taxonomy A two dimensional system • Gentile’s two dimensions taxonomy (1987) – Environmental context • Regulatory conditions (stationary/in motion) • Intertrial variability (no/yes) – Function of the action • Body orientation (stable/transport) • Object manipulation (no/yes) – So there is a 2x2 in matrix in each dimension resulting in 16 skill categories. 8Gentile’s Taxonomy of Motor Skills CLICKER: Function of the action ∙ Watering plants o Body stability/object manipulation o Body transport/object manipulation o Body stability/ no object manipulation o Body transport/ no object manipulation ∙ Environmental context o Stationary regulatory conditions/ intertrial variability o In-motion regulatory conditions/ intertrial variability o Stationary regulatory conditions/ no intertrial variability o In-motion regulatory conditions/ no intertrial variability Bicycling on an indoor track ∙ function of the action o body orientation: body transport o object manipulation: yes ∙ environmental conditions for the solo guy breaking the record: are not changing o regulatory conditions are not changing unless he is changing tracks 9o no intertrial variability because he’s by himself ∙ environmental conditions for the competitive rider o regulatory conditions o with intertrial variability due to competitors CLICKER: opening locked mailbox to get mail (choose number on chart) ∙ Body stability, stationary regulatory conditions, with object manipulation, and no intertrial variability The Measurement of Motor Performance Why study the measurement of Motor performance? • The measurement of performance is essential for: – Performance assessment/evaluation – Motor control and learning research – Tracking progress (deterioration) How to assess performance 1. Determine which aspects of performance should be measured to make (a) valid performance assessment(s) 2. Determine how to measure the identified aspects of performance Tracking progress • Patient • What will determine his/her progress during rehabilitation/deterioration • Performance outcome measures • Performance production measures The two general categories of skill performance measures • Performance outcome – Measures of the result of performing a skill – Action related measures – Performance production – Measures related to specific performance characteristics that produced the performance outcome – Movement related measures Reaction Time • Interval between the onset of a stimulus and the onset of the action • Reaction time and relative difficulty • Reaction time and anticipation • Movement time begins when the RT ends • Response time is RT+MT RT + MT = Response time 10• Types of RT Situations 1. Simple RT (A type): after the gun goes off in the 100m dash, you go right away 2. Choice RT (B type): you need to make a choice (ex: the QB needs to throw as quickly as possible but needs to pick between L RB and R RB—you need to choose the RB without a defender) 3. Discrimination RT (C type or no go RT): a lot of stimuli—3 stimuli, but there is only one that you need to care about (ex: there are a lot of trees that have fallen, but you only have to pay attention to the one that has fallen in your running path) • RT Interval components 1. Premotor time: no activation of muscles—you are still trying to figure out the appropriate muscles to activate 2. Motor time: you have chosen the correct muscles to activate, but the muscle needs a certain amount of activation—the activation is still building up Basic considerations for measures • Objectivity – Two or more observers arrive at the same measurements • Reliability – Measurement is repeatable under similar conditions • Validity – Does the method of measurement measure what the researcher intends to measure CLICKER: Average absolute error of task B relative to task A is (A: ) (B: ) o Is larger o Is smaller o Is about the same o Cannot be compared ∙ Constant error passed the target—the tendency of the person is overshooting the target o Is larger o Is smaller o Is about the same o Cannot be compared ∙ Variable error: o Is larger o Is smaller o Is about the same o Cannot be compared 11CLICKER: (B: ) (C: ) average absolute error of task B o Is larger o Is smaller o Is about the same o Cannot be compared ∙ Constant error o Is larger o Is smaller o Is about the same o Cannot be compared ∙ Variable error: o Is larger o Is smaller o Is about the same o Cannot be compared Error Measures • Performance accuracy • Causes of performance problems – Consistency – Bias • One dimension movement goals – Absolute error: Absolute difference between performance on each trial and goal – Constant error: Signed difference between performance on each trial and goal – Variable error: Standard deviation of the person’s mean score for the series of trials • Two dimension movement goals. – Radial error (similar to AE) – Qualitative assessment of bias and consistency => Look at scatter CLICKER: which has largest radial error? (A. picture below and B. one with three hits outside the circle) ∙ B CLICKER: bias and consistency (A. picture below and B. one with three hits outside the circle) ∙ A has larger bias and shows more consistency ∙ B has larger bias and shows more consistency ∙ A has a larger bias, but B shows more consistency ∙ B has a larger bias, but A show more consistency ∙ A and B cannot be compared 12• Two dimension movement goals. – Radial error (similar to AE) – Qualitative assessment of bias and consistency Look at scatter – Continuous skills – Root-mean-squared-error (RMSE) • General index for performance accuracy • Comparison between the profile of the performance and criterion • Not numerical, but visual • Ex: field sobriety test • Ex: if you have a vision problem, you may stay consistently to the right of the line—look at the profile to see how much you are deviating from criterion CLICKER: A marching leader needs to choose out of several the best drummer. The drummer needs to deliver a drum-beat with exact time intervals for 10 minutes. What measure should be used to figure out who is best? Time is one dimensional ∙ Average Radial Error ∙ Average Root-Mean-Squared-Error ∙ Averaged CE ∙ VE—tests consistency ∙ Averaged AE ∙ You cannot choose a drummer using error-measures Kinematic Measures Motion without regard to force or mass • Displacement—how far we go • Velocity—how fast we move • Acceleration—to see how velocity is changing • Jerk—how smooth the motion is • Linear motion—very good to describe a motion from point A to B • Angular motion—in rehab setting how each joint is moving Measures that reveal the forces that (could) cause motion • External and internal sources of force • Newton’s laws of motion 1. Force is necessary to start, change, stop motion 2. Force influences the rate of change in the momentum of an object 3. Force is involved in the action and reaction that occurs between two objects Electrical activity measures 13• Electromyography (EMG) • contraction of muscle causes force and body moves—shows movement measures the electric potential of the movement and then we look at the movement itself to see what is happening. Used to know what muscles are being activated, shows muscle weakness. • Electroencephalography (EEG) • action potential of brain, problem is that you can only look at cortex and not deeper into the brain. Slow movement while sleeping, thinking in class and mentally engaged you will have fast waves. Where the activity occurs tells which task you are performing. Other brain activity measures • Positron emission topography (PET) • looks at blood flow, need more blood flow in an area means you are activating that area more. Not used very often. • Functional Magnetic resonance imaging (fMRI) • do a particular function and the area that lights up most is the area that is most active at that point, what is the baseline and where is more occurring. Becoming more popular because faster tasks like tapping can be measured. Measuring coordination • Angle-angle diagrams – Cross-correlation technique – Normalized root mean-squared error technique—used when there is no linear relation – Relative phase • Asymmetrical, symmetrical CLICKER: A marching leader needs to choose out of several the best drummer. The drummer needs to deliver a drum-beat with exact time intervals for 10 minutes. What measure should be used to figure out who is best? Time is one dimensional ∙ Average Radial Error ∙ Average Root-Mean-Squared-Error ∙ Averaged CE ∙ VE—tests consistency ∙ Averaged AE ∙ You cannot choose a drummer using error-measures Motor Abilities ∙ Every athlete must find the sport for which he or she is best suited. --Billie Jean King Motor Performance and Abilities • Study of people’s differences • Stable, enduring tendencies for individuals to be different from each other in performance • Stable refers to a trait that you already have, what makes them different from someone else • Stable trait refers to stable when we are mature, while developing the abilities are gaining strength until we reach maturity and stop changing • Trying to predict the level of performance after practice 14• If we practice, it costs time and money • Ex: Olympic trials (trying to predict who would perform best), military (finding the best sniper) Abilities • The performance of a particular skill is strongly affected by the ability of the performer. • All individuals have abilities; Just the pattern of strength and weaknesses on these abilities differ. • Everyday motor tasks require a combination of abilities. Individual motor abilities • Achievement potential – Depends on the motor abilities of the individual as related to the demands of the task • Implications: – It implies that specific motor abilities underlie specific motor skills – It implies that two individuals with the same training experiences will only differ in performance due to their motor abilities – Valuable for predicting future performance success – Debated in research • Not sure what abilities are, we know there is a limited amount but we don’t know how many there are Skills • Proficiency at a particular task • Developed with practice • Modified by practice • Countless in number • Depend on several abilities • Hand-eye, foot-eye, etc. • Without the fundamental abilities for a particular task, high performance levels can never be reached Abilities vs Skills 1. Stable vs Modified ∙ Abilities are stable because they are traits, but skills can be modified through practice 2. Trait vs Developed ∙ Abilities are traits that you have already, but skills have to be developed 3. Few vs Many ∙ There are only a few abilities compared to the mass amount of skills that there are 4. Underlie person’s skill vs Depends on different subsets of abilities ∙ Abilities underlie the person’s skill, but skill depends on different subsets of abilities Views about motor abilities 151. General motor ability: All motor abilities are highly related, there is a single global ability ∙ Soccer players become good golfers 2. Specificity hypothesis: There are many specific, independent motor abilities ∙ Even after training, some soccer players are still bad golfers (“some” doesn’t have to be all) Generality of specific abilities • There are specific motor abilities • How general or specific are abilities? • Strength: Variations of ability or different of abilities • Ex: weight lifting—explosive, repetitive, static CLICKER: One of the differences between a (motor) ability and a (motor) skill is that abilities are relatively stable, while skills can be modified ∙ TRUE Experiments: General Method • People performed different tasks that are assumed to measure variations of a single motor ability Results • High performance on one task should result in high performance on all other tasks and vice versa =>very high correlation between tasks • Performance on the tasks are not related to each other => Very low correlation between tasks, truly not related correlation would be zero Experiment-- Drowatsky & Zuccato (1967) Method • 6 balance tests – Stork stand – Diver’s stand – Bass stick stand – Sideward leap – Bass stepping stone leaps – Balance beam walk • Ex: Differences between 1976 and 2008 Olympic balance beams perfomances • Nadia looked more flexible because she was leaner and also younger (14 years old) • Shawn was older and had more muscle mass (16 years old) • Abilities throughout your life are always changing CLICKER: Results of Drowastky and Zuccato showed that the highest correlation = 0.31 (9.6% shared) What does that mean to the specificity/generalizability of motor abilities? ∙ The tested balance tasks depend on one motor ability ∙ The tested balance tasks depend on two motor abilities; one for dynamic balance skills and one for static balance skills 16∙ The tested balance tasks depend on several different subsets of motor abilities ∙ No correlation Fundamental abilities There are fundamental abilities that can be shared between different motor tasks Example: Timing (Robertson et al., 1999; Spencer & Zelaznik, 2003) • Tapping different rates (400 and 800ms) • Tapping and Drawing lines at the same rate • Different drawing patterns at the same rate Categories of Motor abilities • Fleishman (1964) (The structure and measurement of physical fitness) • He identified several abilities by doing a series of studies with different subjects over several years • Discover what underlying abilities might be There are several abilities: • Perceptual-motor abilities (11) Know which ones belong in which category RT, Manual dexterity, Finger dexterity, Arm-hand steadiness, Multi-limb coordination, etc. • Physical Proficiency abilities (9) Explosive strength, Dynamic strength, Extent flexibility, Stamina, etc. • List is not exhaustive Why is it important to distinguish motor abilities? • Foundation for skills • Measurement of motor abilities • Prediction • Ex: sports—predict the best position for a certain player, so you don’t have to learn other positions • Evaluation • Ex: school—evaluate why a child has a writing problem How is it done? • Estimate strengths of abilities – battery of tests • Based on importance to task – correlations • Ex: firefighter (need to know they won’t be scared to go into a burning building, etc). • Police officer Practical implications • In a group setting expect different abilities and know that performance will be affected • Use task analysis to determine abilities necessary • Identify strong and weak abilities to tailor instruction Remember ∙ We all have these abilities. Some are strong and others are weak. ∙ We tend to gravitate to skills that involve abilities in which we have (a) strength(s). 17The Neuromotor Basis for Motor Control Physiological Foundations ∙ One of the biggest challenges for motor physiology is to understand how we can move as adaptively and effortlessly as we do o Adapt to slippery floor when see a sign, get disease all of the simple things now take more effort ∙ Basic knowledge is needed to understand and appreciate the complexity, capabilities, and limitations of our neuromotor system Neurons ∙ The general structure: o Cell body—one cell body o Dendrites—several, receive all of the information from other neurons o Axons—relays information down to the next cells ∙ Types of Neurons: o Sensory (afferent)—all of the information coming from the outside needs to be taken in and these neurons do that job, specialized, if you lose them they do not come back o Motor (efferent)—relay the information to the proper place, tell what muscles need to be contracted to move, electricity used to relay information, why we can use EMG o Interneurons—all those neurons between sensory and motor neurons, relay information to other neurons, a lot of connections (up to brain, down, everywhere in-between) o For ever sensory neurons there are about 10 motor, for ever motor there are about 200 interneurons Nerve Cells ∙ Synapses—convey messages o Electrical o Most are neurotransmitters (chemicals) o Strengthened with activity and weakened with inactivity o Ex: Work like a telephone Muscles ∙ Produce force by contracting o Force-length relationship—totally extended can not pull any further, close together there is no strength, half way extended is where there is maximum force ∙ Motor unit o Motor neuron and the muscle fibers that it innervates o Number of muscle fibers in a motor unit are different o In general the more muscle fibers in a motor unit the less precise Fingers have motor units with small muscle fibers so they can do fine things, more muscles fibers per motor unit in legs to do larger movements ∙ Motor unit recruitment o The size principle—recruitment of smallest first and systematically progress to the largest last Decruitment—largest first then to the smallest o This order is reduced to the degree of freedom to recruit 18Spinal Cord ∙ A complex system that is critically involved with a variety of systems ∙ Two major parts: o Gray matter o White matter ∙ Sensory neural pathways o Ascending tracts Connect with cerebral cortex and cerebellum Dorsal column—proprioception, touch, pressure Anterolateral system—pain, temperature, some touch, some pressure Spinocerebellar tracts—proprioception (very important in order to make fast movements) ∙ Motor neural pathways o Descending tracts Pyramidal tracts—fine motor skills, trunk rotation (very small number) Extrapyramidal tracts—postural control, inhibition of flexion and extension muscles of hands and fingers --one cannot work without the other, the overlap Brain ∙ 1012 to 1014 neurons with each having up to 104 synaptic connections o a lot of neurons that connect to everything, if you get hit in the head you do not have immediate problems ∙ has functionally distinct centers o not as distinct as you think, some areas are specialized in certain functions ∙ cerebrum, diencephalon, cerebellum, and the brainstem ∙ cerebrum o two cerebral hemispheres connected to each other by corpus callosum o corpus callosum connects everything o cerebral cortex has four distinct areas: frontal lobe voluntary movement parietal lobe sends info to areas occipital lobe visual input temporal lobe judgment, memory ∙ Control of movement o Primary motor cortex Movement initiation (fine motor skills, piano playing) Coordination (grab something—coordinate index finger and thumb to meet) Postural coordination o Premotor cortex (area) Organization (transition from one movement to the next) 19 Mimicking (people with apraxia cannot imitate motions but if you give them the object they can do it) Other people who have problems are stroke patients and brain injury patients o Supplementary motor cortex (SMA) Sequential movements (cannot perform if everything else is not working properly) Preparation and organization of movements o Parietal cortex (lobe) Voluntary movement Integration between preparation and execution With apraxia this area is usually effected the most Make a plan and figure out at what moment you need to begin the next step o ***somebody has trouble with mimicking what is the most likely area that is affected: premotor area o ***somebody has problems with voluntary movement what is affected: parietal cortex ∙ Diencephalon o Second component of the forebrain o Thalamus Receiving, integrating All information received needs to be integrated to make it useful Attention, mood, pain Without attention we do not have voluntary movements Mood is very important for neuromotor control o Hypothalamus Homeostasis regulation Growth control Endocrine system ∙ Cerebellum o Two hemispheres o Movement timing o Eye-hand coordination o Posture control o Involved in motor skill learning—especially in beginning of learning o Execution smooth, accurate movements o Movement error detection (efference copy—send signal to muscles involved and signal to cerebellum that sees if we are doing the movement correctly, before the ball is even let go you know if the ball was let go correctly during the throw) o –policy testing this area of the brain during DUI test o –people with cerebellum problems may appear drunk ∙ Brainstem o Pons Chewing, swallowing, salivating, breathing, control of balance o Medulla 20 Respiration, heartbeat o Reticular formation Integrator of sensory and fine tunes motor neural activity If you want to hit somebody you want to extend your arm, if you are doing this and contract bicep at same time it would not be a good hit, you want to inhibit the muscle activity to make sure this doesn’t happen ∙ Limbic system o Learning motor skills o Control of emotions o Long-term memory—why this area is also involved with learning motor skills because they need to be put in long term memory ∙ Basal Ganglia o Subcortical structure o Caudate nucleus o Putamen o Substantia nigra: black in appearance due to the cells present inside that produced dopamine o Globus pallidus CLICKER: the forebrain consists of the ∙ Cerebrum and diencephalon ∙ Cerebellum and brainstem ∙ Cerebrum and cerebellum ∙ Diencephalon and brainstem CLICKER: The copy of neural signals about a intended movement sent by the motor cortex to the cerebeullum is known as the ∙ Motor output copy ∙ Sensorimotor copy ∙ Efference copy ∙ Cortico-cerebellar copy ∙ Cortexi-cerebelli copy CLICKER: The limbic system is not involved in motor behavior: ∙ True ∙ False Parkinson’s Disease ∙ Neurological disorder—disorder that affects the nervous system o Central nervous system (brain and spinal cord)—mainly affected with Parkinson’s o Peripheral nervous system o Autonomic nervous system—diseases that affect CNS generally start affecting ANS o All diseases start out unilateral, if it starts out bilateral it is not a disease. ∙ James Parkinson (1817): Essay on the Shaking Palsy ∙ Neurodegenerative disease o PD is a slowly progressive disease—attacks neurons 21o Cells in the Basal Ganglia gradually degenerate and die o Results in the reduction of the neurotransmitter dopamine If you lose about 60% of cells that make dopamine, results in 80% loss of dopamine in system, lose 80% of dopamine levels you start to show symptoms of Parkinson’s. At around age 30 people begin to lose dopamine normally. o Decreased levels of dopamine results in the motor deficits associated with Parkinson’s disease o Onset is always unilateral ∙ Tremor at rest—shaking * o Eating, dressing ∙ Rigidity—stiffness * o Painful when walking, want to help someone move their arm passively and there is resistance ∙ Bradykinesia—slow movement * o Reaching a falling cup but you are to slow to grab it, the execution of movement is to slow o Akinesia—slowness in initiating movement Makes the whole movements skill slower because it takes a longer time to initiate the movement and can hardly move, tell someone to start walking and their legs tremble a few times then they take a step ∙ Postural dysfunction—imbalance * o Any standing activity, someone standing still and gets gently pushed they cannot regain balance they keep losing balance and may fall over ∙ Cardinal symptoms *—two out of three symptoms and respond to the drug that deals with dopamine you are diagnosed to have Parkinson’s disease, about 90% of patients are diagnosed correctly ∙ Soft speech, difficulty swallowing, decreased facial expression, loss of sense of smell, depression, micrographia (start to write smaller with less smooth movement) o Researchers think that Hitler had Parkinson’s—he suffered with micrgraphia ∙ Locomotion o Low walking velocity o Small stride length o Shuffling steps—postural instability o Reduced or absent arm swing o Rigidity in trunk movements o Problems in gait initiation o Freezing of gait o Problems in gait switching ∙ Approximately 1.5 million Americans ∙ About 1 out of every 100 people over age of 60 (second most common degenerative disease in Americans over the age of 60, first degenerative disease is Alzheimer’s) ∙ About 60,000 new cases are diagnosed each year in the US ∙ Young-onset Parkinson disease (onset at age 40 or younger) is estimated to occur in 5-10% of patients with PD 22o The prevalence of Parkinson’s isn’t increasing—doctors are getting better at detecting it and detecting it earlier Family history of Parkinson disease in 5-10% of patients CLICKER: Which answer of the following answers does name three cardinal symptoms of Parkinson’s disease? Kinetic tremor, rigidity, postural instability Resting tremor, bradykinesia, rigidity Micrographia, postural instability, bradykinesia Shuffling gait, freezing, resting tremor Freezing, micrographia, resting tremor Motor Control Theories Regulation and Control of Skills ∙ How do we coordinate the many muscles and joints necessary to perform a task ∙ How do we choose between the wide variety of combinations of components available to perform a task ∙ How do we choose order of movement segments needed to perform a task What is a Theory ∙ It must accurately describe a large class of observations o A theory is built on a large number of experiments or observations which are logically related to each other ∙ It must make definite predictions about results of future (unobserved) observations o Predictions made by a theory can be tested o A theory can be disproved by experimental evidence Motor Control Theory ∙ Describes and explains how the nervous system produces coordinated movement of motor skill in a variety of environments ∙ Two important terms: o Coordination—patterning of head, body, and limb movements relative to the patterning of environmental objects and events Two parts to consider: Movement pattern of a skill in relation to a specific point of time Context of the environment of the head, body, and/or limb movements so the actions can be accomplished o Degree of freedom problem Degree of freedom number of independent components that specify the number of ways that the elements in the system can act ∙ elbow joint can vary in two ways: flexion and extension Degree of freedom problem question of how the nervous system controls the many muscles and joints involved in producing a complex pattern ∙ help control several functions at once o hitting a baseball: swinging bat, twisting body and feet position 23o golf: 100 degrees of freedom Control Systems “A part of control is learning to correct your weaknesses” - Babe Ruth ∙ There are two basic systems of control: o Closed-loop control system Closed-loop control (conscious)—motor control is about voluntary movement and therefore most movement is conscious control of movement involving feedback and error detection and correction loop completed from: ∙ executive (decisions) to ∙ effector (carries out the decisions) to ∙ feedback (information about the state of the system) to ∙ comparator (detects errors/discrepancies) to ∙ executive compensation (unconscious closed-loop control) reflexes, involuntary, rapid responses to stimuli low level processes in spinal cord not part of motor control – not a motor skill because it’s involuntary M1 response (monosynaptic reflex) Occurs 30-50 ms after added load Brief, short distance Ex: postural tilt ∙ M2 response (functional stretch/long loop reflex-polysynaptic) o Occurs 50-80 ms after added load interneuron involved o Larger EMG force, longer duration o Ex: knee jerk ∙ Trigger reaction (a little in between) o Occurs 80-120 ms after added load (too fast to be voluntary) o Can be learned—on the cusp of motor learning o ex: not spilling your wine ∙ Voluntary reaction time response (M3 response) o 3rd burst of EMG o powerful and sustained o modified by instructions, anticipation, etc o requires attention—motor control o ex: stabilizing self on bus CLICKER: A monosynaptic reflex is a motor skill (IT IS A REFLEX—CANNOT BE A SKILL) ∙ TRUE ∙ FALSE CLICKER: A polysynaptic reflex is a motor skill (IT IS A REFLEX—IT IS VOLUNTARY) ∙ TRUE ∙ FALSE 24CLICKER: Which of the following closed loop control responses can be considered a motor skill? ∙ M1 ∙ M2 ∙ M3—(voluntary reaction time response) ∙ All ∙ None Open-loop control system ∙ Instructions for the movement are determined in advance ∙ No feedback is used during movement o either action is too fast or just don’t want feedback ∙ Initiated in an “all-or-none” fashion ∙ Action “takes care of itself” ∙ There is no feedback compared to closed-loop Differences Between the Systems o o Open-Loop Control Movement control center movement instructionsmovement effectors Doesn’t use feedback Control center provides all the information for effectors to carry out movement ∙ Does not use feedback to continue or terminate movement o Closed-Loop Control Movement control centermovement instructionsmovement effectorsmovement control center uses feedback control center issues information to effectors sufficient only to initiate movement ∙ relies on feedback to continue and terminate movement ∙ Limitations of Closed Loop Control o Limitations of closed-loop control (conscious, so not compensation) Processing at each stage and feeding information to the next stage requires considerable time and attention 25 Therefore, closed-loop control is slow (about 3-5 adaptations per second) What type of task benefits most from closed-loop control? ∙ Continuous—slow, long duration movements (holding a handstand, biking, walking, running) ∙ Precise—slow, accurate movements o threading a needle ∙ Limitations of Open Loop Control o Limitations of open-loop control Does not control moment-to-moment contraction and adjustments No feedback (often not enough time) What type of tasks benefit from open-loop control? ∙ Discrete—rapid, single pulse movements o throwing, kicking, swinging ∙ Predictable environments – know what’s going to happen o bowling, typing ∙ Slater-Hammel (1960) o Method: Held a finger on a key Clock hand on timer rotated one revolution/sec Lift finger from key to stop clock hand at 8 (800ms) On unpredictable trials, the clock hand would stop before it reached 8 Then must NOT lift finger, do not react o Results: If the clock hand stopped 170 to 210 ms before the 8, the finger was not lifted If the clock hand stopped 150 ms or less before the 8, most people lifted their finger even though they shouldn’t have lifted it o Point of Experiment: It takes about 170 ms to produce a response o Importance: Feedback cannot be used during very fast movements (in this experiment, less than 170 ms) CLICKER: Why is the finding of Slater-Hammel that if the clock hand stopped 150 ms or less before the “8”, most often one could not inhibit the finger lift? ∙ Feedback cannot be used during very fast movements Robertson et al. (1994) o Investigated closed-loop vs. open-loop control Subjects were expert or novice gymnasts Task was walking across a balance beam o Method: manipulate vision (feedback) o Results: Experts performed about the same in all conditions (so, using open-loop visual control) Novices did worse in the no-vision condition (so, using closed-loop visual control) 26 In conclusion, the experts were probably relying on closed-loop proprioceptive control, whereas novices need additional visual control o Point of Experiment: Skill level also influences the type of control the system adopts CLICKER: Why can you only say open-loop visual control? ∙ Because walking on a balance beam is a closed motor skill ∙ Because the experts could have used other types of feedback ∙ Open-loop control is the same as a open-loop visual control, so it does not matter ∙ Because the researcher visually analyzed the performance of the experts ∙ Control vs. Skill o Open and Closed for Motor Skills Look at the environment when the skill begins ∙ If environment is stableclosed motor skill ∙ If environment is changingopen motor skill o Open and Closed Motor Control Systems Look at the information available before action ∙ If all information is available before actionopen-loop control (can be used) ∙ If not all information is available beforeclosed-loop control (best way if there is enough control Theories of Motor Control ∙ Two different theories o Motor program based theory—memory-based mechanism that controls coordinated movement o Dynamic pattern theory (Dynamical Systems theory)—describes and explains coordinated movement control by emphasizing the role of information in the environment and mechanical properties of the body and limbs ∙ Motor Program-Based Theory o Set of muscle commands that are organized in advance and run off without much feedback (open) o “all or none” initiated then carried out without modification o analogous to computer program—can only do what it’s programmed to do o specific instructions to muscles: which muscles, what order, what timing and sequencing, what duration o CD analogy—CD defines which sounds occur and in what order, duration, and timing ∙ Evidence for Motor Programs o Reaction time increases as the complexity of the movement increases RT is longer because more time is required to organize the action o Complexity can be increased by: Adding elements to an action, involvement of more limbs, longer duration skills ∙ Not the same as difficulty Henry and Rogers (1960) o Method: 27 Respond as quickly as possible to a light o Three different responses: Lift the finger Lift finger, reach and grasp a ball Lift finger, hit several targets in different directions o Results: RT increased with added complexity of task (150, 195, 208 ms, resp.) The same stimulus One response o Point of Experiment: Increased RT occurred due to a more complex response ∙ Evidence for Motor Programs Continued o Deafferentation Experiments Cutting sensory nerves so the CNS does not receive sensory information What are we capable of when deprived of feedback from the limbs ∙ Taub and Berman Experiment (1968) o Method: Deafferented (eliminate nerves) upper limbs of monkeys o Results: Monkey still able to climb, and chase However, difficulties with fine motor control (eating) o Point of Experiment: Commands for some actions must be organized centrally and are not critically dependent on feedback ∙ Wadman, Denier van der Gon, Gueze, and Mol (1979) o Effects of mechanically blocking a limb o Method: Examined muscle activity during quick limb movement On some trials the movement was unexpectedly stopped by the experimenter o Point of Experiment: Even though the limb did not move a similar pattern and timing of muscular action was measured for the first 120 ms ∙ Limitations of the Motor Program Theory o Novelty problem How is a novel movement produced? Isn’t every movement novel in some way—every time we do something we do not do it exactly the same, so every skill is a little bit novel, if the motion is done in a different situation then a new motor program is needed o Storage problem How do we store the countless number of motor programs—need a new motor program for every movement storage becomes a problem Limited storage and retrieval capacity—capacity to retrieve everything is a problem, how can we retrieve fast if there are so many programs available ∙ Solution: Generalized Motor Program (GMP) o A stored pattern that can be modulated slightly 28o Allows the movement to be adjusted to meet altered environmental demands Generalized motor program—hypothesized memory-based mechanism responsible for adaptive and flexible qualities of the human movement ∙ If something changes in environment we can adapt, it is memory based so there is some kind of abstract portion which means we can modulate and change it Proposed that each GMP controls a class of actions that have common invariant characteristics ∙ If you throw something your arm pulls back and then flings forward and releases object, this is an overhand throw—you can throw a baseball, tennis ball or stone and all you would have to adjust is a little bit of hand movement and adjust to the weight difference Best example comes from “Schema Theory” by Schmidt (1988) – using generalized motor program ∙ GMP function o Basis for generating movement instructions prior to and during the performance of an action Allows slight adjustments during performance, can now use it in an open motor skill ∙ GMP characteristics o Invariant features Does not vary within class of action Identifying signature—overhand throw what doesn’t vary is that the arm is pulled back, flung forward, and ball released o Parameters Specific features which need to be added for performance Does vary from one performance of a class of action to another Ex: putting more force into a throw to make it go further, direction of throw—general pattern and you incorporate what you need to adapt o Example of an invariant feature: Relative or percentage time/relative or percentage size o Example of a parameter: Overall or absolute time/overall or absolute size o Analogy from music and dance: 1. Rhythm (beat) of music—kept the same—invariant 2. Tempo—fast and slow movement—parameter CLICKER: When comparing the movement components of task A and B (A was 3 sec with 4 sequences, and B was 5 secs with same sequence and percentage) 1. A and B have the same GMP 2. A and B have different GMPs (see sequence) 3. A and B have different GMPs (see percentage) 4. A and B have different GMPs (absolute time) 5. A and B have different GMPs ( see sequence and percentage) 6. A and B have different GMPs (see sequences, percentages, and absolute time) CLICKER: When comparing the movement components of task A and B (A and B were same time but flipped sequences 1. A and B have the same GMP 2. A and B have different GMPs (see sequence) 3. A and B have different GMPs (see percentage) 294. A and B have different GMPs (absolute time) 5. A and B have different GMPs ( see sequence and percentage) 6. A and B have different GMPs (see sequences, percentages, and absolute time) CLICKER: When comparing the movement components of task A and B (A and B were same time but flipped percentages) 1. A and B have the same GMP 2. A and B have different GMPs (see sequence) 3. A and B have different GMPs (see percentage) 4. A and B have different GMPs (absolute time) 5. A and B have different GMPs ( see sequence and percentage) 6. A and B have different GMPs (see sequences, percentages, and absolute time) ∙ Invariant Characteristics—Relative Time and Sequence o Same GMP—sequence of events are constant and percentages are the same o Different GMP—different sequences and different time percentages ∙ Evidence for GMP o Variations in Movement Amplitude o Hollerbach Experiment (1978) Method: ∙ Write words of different sizes Results: ∙ The same pattern was produced, just with different amplitudes of movement Point of Experiment: ∙ Overall pattern is the same, force required to make different sized movements can be modified o Variations in used Effectors (effector = parameter) Raibert Experiment (1977) ∙ Method: o Write a sentence with right hand, right arm, left hand, mouth, and foot ∙ Results: o The writing style looks the same ∙ Point of Experiment: o The GMP can be the same and the types of muscles used can be modified o Variations in movement time Armstrong Experiment (1970) ∙ Method: o Produce four direction-reversals at the elbow joint ∙ Results: o When the first segment of the movement was performed too fast, the whole movement was performed to fast o The pattern of the movement was preserved, the overall time was adjusted and the relative times stayed the same 30∙ Point of experiment: o Relative time is invariant (GMP); overall time is not (parameter) o Running and walking invariant: relative time for gait phases parameter: walking speed Shapiro et al Experiment (1981)—used gait characteristics to test prediction of relative time invariance for a class of action controlled by a GMP ∙ Method: o Assessed four components of one step cycle o Used nine speeds o Calculate relative time of a full step cycle Relative time= % of total time each component required for one step cycle ∙ Results: o Relative time similar within speeds of walking or running, but relative time was different between walking and running o Running and walking are two different generalized motor programs CLICKER: Open-loop controlled motor skills are externally paced because the environment is unpredictable (i.e. the regulatory conditions are in motion) during the action. A. True B. False o Dynamic Systems Theory (Dynamical Pattern/Ecological theory) o Describes the control of coordinated movement that emphasizes the role of information in the environment and dynamic properties of the body/limbs We know our limitations—we know if we can bend and reach something or if we need to take a step to reach it o Began to influence views about motor control in early 1980’s o Views the process of human motor control as a complex system that behaves like any complex biological or physical system 31o Concerned with identifying laws (natural and physical) that govern changes in human coordination patterns Not linear, sudden o Motor control system operates on the basis of non-linear dynamics: Behavioral changes are not always continuous Behavior is specified by the environment and the characteristics of the task Behaviors are self-organized (we take the information in from the environment and task at hand and we also have all of the information of limitations of our system and we come up with the best solution for that moment, how we adapt) o Movements are thought of as the end product of a system o The system is made up of many cooperating and sometimes competing subsystems gravity vs. arm muscles o Subsystems can be internal to the performer or external Effectors—the body Task—what are we trying to achieve Environment—environment competes against completing tasks o Movement is a product of cooperation of many subsystems in the body Strength, balance, coordination, etc. Motivation, attention, etc. (if you are not thirsty or do not notice the cup of water sitting next to you, you won’t want it) o Movements are flexible-assembled and self-organized Subsystems differ in importance for different skills under different circumstances o The assumption is that the system has the autonomous ability to find stable solutions, even if they are more complex, which can lead to more efficient, effective and consistent behavior o New forms of behavior arise out of old forms o Perturbations disrupt the stability in old forms and give rise to new behavior being in a new environment, new motivation o The movement product is formed by the three subsystem components o The movement product varies in relation to the three subsystem components (lose leg—come up with solution and learn to walk with prosthetic leg) The three subsystems are sometimes also called the movement constraints o There is a disorganizing tendency of the universe The system overcomes this disorganizing tendency by striving for order and complexity (funnel cloud, galaxy, school of fish) The system utilizes resources from the environment, task, and the body to organize and facilitate movement o Concepts of Dynamical Systems o 1. Attractor—stable state of the motor control system that leads to behavior according to preferred coordination patterns (why we recognize walking as walking, throwing as throwing) Identified by order parameters (not the same as GMP parameter) 32 Control parameters influence order parameters Minimal trial-to-trial performance variability (because of stability) Stability (same pattern still present) Energy efficient o 2. Order parameter (collective variables)—parameters that exert compression of multiple degrees of freedom of the system The dimension of the system that expresses the underlying pattern that emerges from the cooperation of the elements (take into account limitations of body, size of ball, environmental factors and this is the pattern that emerges) It enables a coordinated pattern of movement that can be reproduced and distinguished from other patterns ∙ Relative phase a very very stable order parameter = an attractor state o 3. Control parameter—move the system through its collective dynamic attractor states (varied forms of movement) Example: speed Control parameter can be manipulated to asses the stability of the order parameter (turn treadmill speed up to 8.5) Once the control parameter reaches a critical point, a phase shift occurs and another movement pattern emerges (treadmill speed of 8.5 for someone with long legs may still be walking but if they have short legs at this speed they may be running) It provides the basis for determining attractor states for patterns of movement (can change this and see where it is stable, there is an unstable point at some point) o 4. Self-organization—when certain conditions characterize a situation, a specific pattern of movement emerges This pattern of movement self-organizes within the characteristic of environmental conditions and limb dynamics Example: when there is no wind you cannot lean forward while walking, when wind picks up you may have to lean forward to walk Example: people taller, heavier, longer arms—taken into account along with what is happening in the environment o Coordinative Structures o Functional synergies of muscles and joints that act cooperatively to produce an action o Developed through practice, experience, or inherited Example: prosthetic developed through practice and experience Example: hammering a nail o Perceptual-Action Coupling o linking together of movement to information from the environment o perceptual—detection of critical invariant information in the environment immediately begin to recognize certain situations o action—movement that becomes associated with what is specified by environmental information 33 perceive something and immediately know what kind of movement needs to be done to accomplish the action Ball Example o Ball in stable state—order parameter o Give it so much force it will go over the peak—control parameter o Too much force and it will fall in the next valley o The next valley is the next stable state o --performing an action and change something and it gets worse until you realize it is actually better than before which is another stable solution that is even better than before b. ∙ ∙ Present State of the Control Theory Issue o Both motor program-based theory and dynamic pattern theory dominate o Research using both approaches has shown that a theory of motor control cannot focus exclusively on movement information specified by the CNS Cannot say this is what people are always doing because the environment is always changing things o Probably a hybrid of the two theories could emerge to explain control of coordinated movement what Van Gemmert believes strong TEST: -40 questions ∙ -30 multiple choice ∙ -10 true false ∙ -even throughout the chapters ∙ don’t know: any years, dates, no pictures CLICKER: Which of the following answers shows a limitation of the (traditional) motor program theory (TMP) that was solved (partly) with the generalized motor program theory (GMP) 34∙ The TMP has a difficulty to explain how we choose between the infinite number of degrees of freedom available to us--degrees of freedom problem ∙ The TMP has a difficulty to explain how we coordinate our limbs, body, and head during actions--coordination problem ∙ The TMP has difficulty to explain how we are able to perform fast paced discrete movements--discrete pacing problem ∙ The TMP has difficulty to explain how a novel movement is produced-- novelty problem ∙ no limitations of TMP that were solved by GMP 35