Flashcards
SS9606
Cards in this deck (25)
- 1Hierarchy of motor actions: infant reflexes ->> rudimentary movement skills ->> fundamental motor skills ->> sport specific skills Movement = patterns of motion for accomplishing action goals; concomitant signaling to multiple joints for meaningful actionsReflex arc - phasic movement, mediates movement before sensory signals reach the brain
Circuitry of volitional movements: stimulus identification (from external space) -> response selection -> response programming (information processing, prepares motor apparatus) -> action - 2Motor actions = combination (not coordination) of movements (many-to-one, one-to-many) for attainment of goals; unrefined, uncoordinated, high levels of errors Motor skills = coordinated movements resulting in purposeful motor actions with consistent attainment of goalCriteria for classification as motor skills: consistency / efficiency / reproducible under wide range of circumstances and conditions
Purpose of motor skills classification: understand variables (movement / environmental) that influences skill performance / better design practice - 3Motor control = neuromuscular functions to activate + coordinate muscles + limbs involved in performance of motor skill Motor learning = acquisition of novel motor skills / performance enhancement / re-acquisition / improvement due to practiceMotor control vs motor learning: overt vs not observable / specificity of time and situation vs inferred from characteristics over a period of time
- 4One-dimensional classification: gross (low precision high force) vs fine/ discrete (clearly defined start / end) vs continuous (repetitive / cyclical, ending may look the same as starting) / serial (series of discrete skills) / closed vs open (non-stationary environmental variables imposed on movement)Problems with one-dimensional classification: does not capture complex properties of certain skills / inadequate information for practitioners to make decisions (eg instructions / practice routines / therapy regimes)
- 5Gentile's 2D taxonomy: environmental context (stationary regulatory vs in-motion regulatory) x intertrial variability (properties of skill performance change from one trial to next) x body (stability vs transport) x object manipulationApplication of taxonomy: insights into demands of skills imposed on performer / evaluation of movement capability and limitations / selection of progressively functional activities / charting progress towards performance goals
- 6Performance outcome measures (qualitative / quantitative) = results of performing a motor skill eg time / distance / height / errors / successful trials / 3-point shooting percentage / ball possession statistics False start = RT <100ms (anticipatory attempt)Performance production measures = specific aspects of motor control system during performance of motor skill (nervous / skeletal / muscular function); not necessarily looking at scales
Types of performance production measures: kinetics (forces / joint torque) / kinematics (s / v / a) / neurophysiological - 7Force measurements: force plate (for GRF) / force transducers or strain gauges (detect muscular tension / compression) Motor response measures: RT (stimulus to initiation) / movement time (onset of movement to completion) M1 responsible for response programming into neural signalsTypes of RT: simple (1 stimulus -> 1 response) / choice (>1 stimuli, each requiring own response) / discrimination (>1 signal, only one requires response)
RT is worse if it requires separate actions for each stimulus vs simply go or no-go / if instruction conflicts with priori subconscious experiences - 8Neurophysiological measures: concern functioning of brain in relation to other body systems eg muscles (EMG) / electrical fields (EEG) / blood flow (fMRI, measures blood flow / oxygenation).
- 9EMG - electrodes attach to skin / insert into muscle; ground electrode as baseline to complete circuit RT: premotor component (stimulus identification + response selection + response programming) + motor component (muscle activity on top of baseline)EMG activity recorded as percentage of maximum peak, signals start @ motor component of RT (overcome inertia); antagonistic muscles normally one after another (not supposed to have co-contraction leading to joint freeze)
- 10EEG places electrodes on scalp, records electrical fields exiting skull; takes pathway of least resistance (very random fields, need sophisticated source location algorithm for deep ones) ERP = actual event :/: baseline Take out eyeblinks because EOG potential higher than EEGEEG processing procedures: bandwidth filtering (collect >1 just in case need to shrink it down) -> events list (instruct to subjects, inform machine where the event is) -> epoching (actual event vs baseline, usually @ 10s when brain is getting ready) -> artifact detection (take out false actions) -> average epoch
- 11fMRI outputs different images, only isolating brain; poor temporal resolution (vascular response ~4s) Vascular response occurs by metabolic + synaptic signalling Blood flow + oxygenation increased because brain area starts to run out of oxygen -> signal to lungs + heart.
- 12Motion parallax provides depth cues Optical array - stationary position; transformed into optic flow during movement.
- 13Somatosensory neurons: free (pain / heat / cold) / Merkel (sustained, pressure) / Meissner (slow vibration, texture) / Ruffini (deep pressure) / Pacinian (rapid vibration) / Krause end blubs (rapid vibration) / root hair plexus (hair movement)Semicircular canals (rotational acceleration): horizontal (transverse) / anterior (sagittal) / posterior (coronal); saccule + utricle - linear acceleration
Muscle spindle - change in muscle length; GTO - change in muscle tension; joint capsule - somatosensory @ joints - 14Local interneuron - short axon, forms circuits with nearby neurons for small pieces of information; relay interneuron - long axons, connects between circuits @ different regions of brain.
- 15Stimulus identification @ S1 + posterior parietal (secondary somatosensory) -> response selection communication between S1 / posterior parietal xx SMA (posture / bimanual coordination / sequence) / premotor (movement planning / sensory guiding) -> response programming @ M1Cerebellum - more neurons than cerebrum, involved in coordination + motion memory; may have other non-motor functions eg cognition
Basal ganglia - interconnected with cerebral cortex, prepares voluntary movements, involved in procedural learning + emotions - 16Henneman's size principle: smallest motor units (fewer synapses) recruited first -> systematically progresses to larger motor units -> progress until combined force generation yields criterion level.
- 17Dynamical systems theory = role of environment + dynamic properties of body in (non-continuous) control of coordinated movement; focus on interaction between elements (environment x organism x task) Stable system - preferred state; unstable system will spontaneously revertAttractor states = behavioural steady states (HKB model)
Order parameters = variables that define overall behaviour; control parameters = variables that freely change
Self-organisation = emergence of specific stable pattern of behaviour - 18Degree of freedom problem (Bernstein): nervous system has to solve a movement problem, system constraints for many degrees of freedom to produce specific result via neuromuscular controlLearning a novel motor skill: brain does not know which muscles to activate to bring about combination of optimal limb movements (problem augmented if requires many joints) -> redundancy (activate more muscles than required at first) + co-contractions -- many errors, uncoordinated
- 19Motor program based theory = memory representation stores information needed to perform action (no information if novel, many errors); full of variables with various columns (updated during error to better control movement)Challenges to motor program based theory: memory capacity and location for motor program information / computation process to select best motor program (probably not iteratively)
- 20Schmidt's hypothesis: GMP (memory representations combining different movements as one, each sharing common similar invariant features eg relative time / sequence) -> movement specific parameters (variables varied across skills, added to invariant features to meet movement demands)Schmidt's schema theory: abstract representation of rules that govern movement; combine information from past experiences into type of rule -- may help to solve degree of freedom problem via executive control to organise motor programs + schemas
- 21Fitt's law: movement time = a + b + (b * log2 (D/W)) Woodworth's hypothesis = initial movement via open loop (specified by motor program) -> closed-loop feedback (involves sensory information); related to speed\accuracy tradeoffOpen loop components: desired state (from motor program) -> feedforward controller (M1?) -> motor command to muscle; closed-loop components: proprioception combined from GTO + muscle spindle + joint capsule -> input processing -> comparator (cerebellum?)
- 22Movement preparation in reaching movements: sensory systems determine regulatory conditions (eg properties of target / object, may be influenced by pre-coding of motor action by illusory input); CNS integrates sensory inputs -> prepares code to initiate actionInitial flight phase involves proprioception + vestibular sense (\ vision plays minor role) -> vision of limb and target is crucial @ termination phase to convey movement accuracy to CNS -> determine corrections needed
- 23Invariant features in reaching-to-grasp movements: hand closure ~67% movement time regardless of object size and distance \ absolute movement time affected by size of handle (Fitts' law) Limb velocity reduces as hand approaches target to ensure accuracy.
- 24Catching movements: no arm movements @ initial flight phase (stimulus identification) -> emergence of elbow flexion + finger extension -> hand withdrawal @ ~50% ball flight time (rotational inertia easier if ball is closer)Role of vision in catching (especially 200-300ms before contact): combines extrinsic + intrinsic sensory information to code for precision prior to tactile information (feedback to CNS to make force adjustments)
CNS can use intermittent snapshots \ less accurate - 25Run-to-jump movements: stride length increased at relatively constant rate @ initial phase (open loop) -> consistent stride length for optimal force speed @ mid-phase -> adjust for cumulative movement errors @ late phase from inconsistencies @ previous phases.
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- None Sport Science Flashcards on SS9606, created by Andrew Susilo on 28/09/2021.
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