MOTOR: Exam I Flashcards
Fitts and Posner
- Cognitive stage
- Associative stage
- Autonomous stage
Cognitive
– Thinking about learning
– Experimenting with strategies
= Most basic stage of motor skill acquisition
Associative
- Refining selected strategy
- Skill develops and improves with practice
Autonomous
– Automaticity of skill
– Attention diverted to scanning environment or multi-tasking
= Expert stage
NOTE: Not truly autonomous if performance declines when distracted
- May still be highly skilled/”expert”, but not totally automatic
- Truly “perfect” performance is rare; usually some error due to distraction
Theories of Motor Learning and Performance
- Fitts and Posner
- Newell
- Schmidt and Lee
- Gentile
NOTE: Basic elements
Fitts and Posner
- Cognitive stage = thinking
- Associative stage = refining
- Autonomous stage = automaticity
Newell
- Novice stage = basic patterns
- Advanced stage = coordination
- Expert stage = controlled
Schmidt and Lee
- Short-term, implicit memory
- Schema: Recall, Recognition
Gentile
- Closed to open skills
- Demands of environment
- Context vs. Regulatory Variability
- Requirements of action
- Object manipulation
- Body transport
Newell
- Novice stage
- Advanced stage
- Expert stage
Novice
- Understanding basic patterns of movement
- Few degrees of freedom
- Highly variable movements trial to trial
Advanced
- Coordination
- Increasing degrees of freedom
- Adds cognitive element
- Increasing consistency of movement
Expert
- Controlled
- Modifying movement to perform desired task (as needed)
- Variability is a sign of skill
- Consistent outcome, but pattern of movement may vary
- Ability to adapt to changes in environment
NOTE: Difference in variability between novice and expert
- Novice variability in outcome
- Expert variability in pattern to achieve outcome
Schmidt and Lee
- Development of schema
- Components of schema
Schema = set of rules for performing a movement
Development of schema: All add to our memory of movement
– Short-term, implicit memory of movement components
– Initial movement conditions (e.g., body position, object weight)
– Motor program parameters = patterns of muscle activity
– Knowledge of results (KR) = outcomes or goals of movement
NOTE: Need to decide what error range is acceptable for successful outcome
– Goal of training is to narrow range, but experiencing error critical to learning
– Even experts never perform same task same way every time
– Sensory consequences = experience or perception of movement
– Feedback from multiple sensory systems (e.g., sight, feel, sound)
Components of schema:
– Recall = Set of rules for movement under different conditions
– Common elements of action and organization (i.e., temporal, rhythmic)
– Memory of movement in different environments/conditions
– Expert has ability to adapt to ensure successful outcome
– Recognition
= Rules of movement coupled w/ current conditions
»_space; Expected outcome
– Expert element of schema
– Recognizing what to do under different conditions
Gentile
- Two-dimensional classification system
- Demands of environment
- Regulatory variability
- Context variability
- Requirements of action
- Closed skill
- Open skill
Two-dimensional classification system:
= Matrix combining demands of environment X requirements of action
– Spectrum of complexity from closed to open skills
– Demands of environment:
– Regulatory variability = stability of environment
Ex: Moving escalator vs. stairs
– Context variability = persons movement in environment
Ex: Standing still vs. balancing on opposite legs
– Progression: Low to high complexity
– Neither RV nor CV
»_space; Only CV»_space; Only RV
»_space; Both RV and CV
– Requirements of action:
– Progression: Low to high complexity
– Neither body movement nor object manipulation
»_space; Only object manipulation»_space; Only body movement
»_space; Both object manipulation and body movement
Closed skill = Performed in stable and predictable environment
Open skill = Performed in unstable and unpredictable environment
– Must use perception and decision-making to adjust movement
NOTE: Most skills somewhere between totally open or closed
Definition of terms:
- Motor learning
- Motor performance
- Motor control
Motor learning = acquiring skilled movement as result of practice
= Internal process that determines capability
– Practice = process of squiring skilled movement via repetition
– Characteristics:
– Improves with practice and experience
– Assessed by observing performance for several trials
– Stable under varied circumstances (repeated trials)
Motor performance = observable action or skill
- Fluctuates day-to-day and trial-to-trial
- Characteristics:
- Influenced by:
- Fatigue, pain, and conditioning
- Motivation
- Attention (distraction)
- Physical conditions
- Environment
Motor control = study of neural, physical, and behavioral aspects of movement
- How our brains and bodies and behaviors relate to this movement
- How we control the movement skill: brain, muscles, and behaviors
Types of skill:
- Motor skill
- Cognitive skill
- Discrete skill
- Serial skill
- Continuous skill
Motor skill = success determined by quality of movement
– Knowing “how” to do the movement
– Emphasis placed on correct performance
– Decision making is minimized and motor performance is maximized
Cognitive skill = having a strategy for movement
– Knowing “what” to do
– Movement less important than decision guiding movement
– Decision making is maximized and motor performance is minimized
NOTE: Most skills are a combo of motor and cognition
– Usually new skills require more cognition than more proficient skills
Discrete skill = distinct beginning and end
Serial skill = discrete actions linked together
Continuous skill = no distinct beginning and end
Feedback:
- Intrinsic
- Extrinsic or Augmented
- Knowledge of Performance (KP)
- Knowledge of Results (KR)
Intrinsic = info about movement from sensory systems
– Can be confusing since we get input from many systems
Extrinsic = supplemental info from command or cue
NOTE: Manual and verbal cueing would be both intrinsic and extrinsic
KP = info about movement or movement pattern used to achieve outcome
– Compared to intended movement
KR = info about outcome of movement
– Compared to intended outcome
Practice:
- Massed
- Distributed
- Constant
- Variable
- Whole
- Part
- Guidance
- Discovery
- Random
- Blocked
- Transfer of practice
- Mental practice
NOTE: Easier»_space; Harder
Massed = time in trial > interval time
Distributed = time in trial < interval time
– More difficult with longer interval between trials (requires recall)
Constant = static or stable conditions for practice
Variable = differing conditions for practice
– Changing surfaces, external environment, etc.
Part = break task into components or interim steps Whole = practice entire task as is
Guidance = physical or verbal instructions through task
Discovery = trial and error
– Discovery can be frustrating, unsafe, time-consuming
– Try to become more efficient in discovery
Blocked = practice one task for period of time, then move to other Random = practice different tasks in random order
Transfer = better transfer between similar skills/movements Mental = thinking about task (w/o doing) may improve performance
Recovery of function
- Compensation
- Spared function
- Stages of recovery
- Factors affecting recovery
Recovery = regaining motor skill
Compensation = learning new way to achieve same outcome
Spared function = some ability remaining that can be used
Stages:
- Spontaneous = suddenly able to perform skill
- Forced = prolonged process of recovery
Factors:
- Age
- Injury or lesion (type, extent, location)
- Pre-injury motor skills (e.g., child still developing)
- Post-injury factors (e.g., PT, meds, tissue healing)
Problem-Based Approach
- Who?
- What? Why?
- Where?
= Key to learning is ability to ask right questions:
Who = characteristics of learner
- Abilities
- Experience
- Motivation
What/Why = goal of task
Where = target context
- Environment task will take place
- Attempt to make practice setting as close to actual
Levels of sensory input
- Interoception
- Exteroception
Interoception = internal sensory feedback
- Information from inside the body
- Hunger, fullness, thirst, and pain
Exteroception = sensory feedback from outside body (external environment)
– Vision = dominant source
– Hearing = “audio flow” indicates location, direction, and directs attention
– Olfaction = may trigger movements or reactions
– Proprioception
= Info about body’s position and orientation in space
– From vestibular system, muscle, joints, and cutaneous receptors
– Vestibular = orientation of head relative to gravity
– Other receptors = location of body parts in space
Kinesthesia = Info about limb movements and muscle contractions
Proprioceptive sensory mechanisms
- Muscle spindle
- GTO
- Joint receptors
- Cutaneous receptors
Muscle spindle:
– Located within skeletal muscle fibers (extrafusal)
– Detects muscle lengthening
– Rapid length change»_space; Stretch reflex = Muscle contracts
– Slow length change»_space; No reflex
– Afferent fibers carry signal to spinal cord
– Motor neurons signal spindle fibers to reset length (intrafusal)
»_space; Remains sensitive to length changes
GTO: Golgi Tendon Organ
- Located in musculotendinous junction
- Detects changes in muscle tension (force generation)
- Inhibits muscle force (damps) to protect muscle and tendon
Joint receptors:
- Free nerve endings
- Pacinian corpuscles
- Ruffini endings
- Golgi type endings
Cutaneous receptors:
- Free nerve endings
- Pacinian corpuscles
- Ruffini endings
- Meisners corpuscles
- Merkels discs
Joint receptors:
- Free nerve endings
- Pacinian corpuscles
- Ruffini endings
- Golgi type endings
Cutaneous receptors:
- Free nerve endings
- Pacinian corpuscles
- Ruffini endings
- Meisners corpuscles
- Merkels discs
- Krauses end bulbs
- Hair follicle receptors
Joint receptors:
- Free nerve endings = pain and non painful stimuli, biochemical stimuli
- Ligaments, synovium, fat pad, joint capsule
- Pacinian corpuscles = vibration (high freq.), acceleration, high vel. change in joint position
- Fibrous layer of joint capsule
- Ruffini endings = vibration (low freq.), amplitude, stretch of capsule
- Fibrous layer of joint capsule
- Golgi type endings = compression of capsule, tension, stretch of ligaments
- Ligaments, joint capsule
NOTE: All provide info to central processes, but none are conscious except pain
Cutaneous receptors:
- Free nerve endings = pain and non painful stimuli, biochemical stimuli, temp
- Pacinian corpuscles = vibration (high freq.), pressure (deep touch)
- Located in dermis (deeper), resets itself
- Ruffini endings = vibration (low freq.), stretch of skin
- Meisners corpuscles = light touch (not sustained), vibration (freq. < 50Hz), speed of stimuli
- Merkels discs = light touch (sustained, very sensitive)
- Krauses end bulbs = touch, pressure
- Hair follicle receptors = movement of hairs on skin
NOTE: Incredibly rich, sensitive, and important source of info
– Respond to chemical, thermal, and inflammatory stimuli
Sensory pathways
- Spinothalamic pathway
- Spinoreticular pathway
- Dorsal column pathway
Spinothalamic = pain and temperature
– Dorsal root > Dorsal horn (synapse 1)
> Cross in anterior cord > Ascend in anterolateral tract
> Thalamus (synapse 2) > Sensory cortex
Spinoreticular = pain
– Dorsal root > Dorsal horn (synapse 1)
> Cross in anterior cord > Ascend in anterolateral tract
> Reticular activating area (multiple synapse)
> Sensory cortex (multiple areas)
Dorsal column = touch, pressure, vibration, and proprioception
– Dorsal root > Ascend in dorsal column
> Cuneate or gracile nucleus (synapse 1)
> Cross in anterior medulla
> Thalamus (synapse 2) > Sensory
Visual system:
- Focal vision
- Ambient vision
- Visual dominance
- Visual capture
– Optical flow
Focal vision = identifies objects in center of visual field
– Conscious and affected by light (center of retina = fovea centralis)
– “What is it?”
– Slow, exteroceptive loop (via cerebellum to info processing) = conscious
Ambient vision = detects orientation of body in environment
– Non-conscious and peripheral (light moves across retina)
– Used a lot in movement control
– “Where am I?” or “Where is it?”
– Fast, inner loop (output to motor program) = nonconscious
Visual dominance = visual info dominates info from other senses
– Primary source of sensory input
Visual capture = visual info captures attention more easily than other sources of info
Optical flow = detects patterns of light moving across retina (ambient vision)
– Perceives:
– Motion
– Direction (left or right, towards or away)
– Velocity (across, towards, or away)
– Position
– Stability
– Size of object
NOTE: Perception of movement can be confusing (you moving in environment vs. environment moving around you); optical flow perceives movement of environment, vestibular system helps you determine if visual info is real (vs. you are moving)
Compensations for muscle movements
- Mechanical
- M1
- M2
- Triggered response
- M3
Compensations = corrections for error in movement
Mechanical = tissue stiffness helps stabilize
M1 = monosynaptic reflex
– Latency = 30-50 ms
– Very rapid, unconscious, limited muscles
– Inflexible, little environmental impact
– No adaptability, effect of instructions or effect of alternatives
M2 = polysynaptic reflex
– Latency = 50-80 ms
– Longer pathway, still unconscious
– Not voluntary, but can be modified/inhibited consciously (involves higher brain centers)
– Low adaptability, effect of instructions or effect of alternatives
Triggered response = rapid, learned, well-practiced response
– Latency = 80-120
– “Wineglass effect”, subcortical but conscious, cutaneous receptors
– Moderate adaptability, effect of instructions or alternatives
M3 = voluntary reaction
– Latency = 120-180 ms
– Much longer pathway (> sensory cortex > motor cortex > muscles)
– Very large adaptability, effect of instructions or alternatives
– Influenced by instruction, anticipation, and stimulus responses
NOTE: Any additional demands on attention will slow reaction time even further
Closed-Loop Control System
- Characteristics
- Components
Open-Loop Control System
- Characteristics
- Components
Closed-Loop = Ongoing modification of movement using peripheral feedback
- Uses feedback, error detection, and correction processes during movement
- Slow, deliberate movements (Requires sensory input to guide movement)
- > 200 ms (M3 voluntary reaction time): Corrections occur a few 100 ms after error
- Effective in unpredictable and unstable environments
- Components:
- Input = Environment or desired action
- Executive = Determines actions (motor planning areas of brain)
- Comparator = Error detection (cerebellum)
- Compares efferent copy of motor plan from brain w/ sensory feedback
- Effector = Carries out movement (spinal cord, motor tracts, muscles)
- Output = Outcome of action
- Feedback = Info about current state (sensory receptors, afferent pathways)
Open-Loop = Rapid, automatic movements w/ no correction during movement
– Response selection and programming occur before movement (preplanning)
– Triggered as a whole; No error detection or sensory input during movement (too quick)
– < 200 ms (only reflex corrections M1 and M2)
– Effective in stable and predictable environments
– After movement (subsequent trials): Error signal processed (stimulus ID stage)
»_space; Movement correction chosen (response selection)
»_space; Modifications organized and initiated (response programming)
– Components: Input»_space; Executive»_space; Effector
– NO COMPARATOR
– Output»_space; Feedback only after movement is complete
NOTE: Closed and open loop do not act in isolation
Motor Program as Open-Loop System
- Components
- Characteristics
- Attention
- Practice
- Learning
- Storage
Components
– Input = Stimulus (e.g., ball is thrown) (sensory systems)
– Executive (cortical areas: frontal, parietal, temporal, occipital)
– Stimulus Identification (e.g., see ball thrown)
– Response selection (e.g., decision to swing bat)
– Response programming (e.g., how fast and hard, where to swing)
= Preplanning based on sensory inputs and past experience
– Motion and force predetermined
– Effector
– Motor program = code for movement (premotor/motor areas, basal ganglia)
– Spinal cord (and motor tracts) = signal for movement
– Muscles = perform movement
Characteristics
- Stages of processing used to develop motor program (executive)
- Little attention needed for movement once program starts
- Effect of practice
- Program can control longer sequences
- Movements become more elaborate
- Effect of learning
- Less time needed for programming
- More focus on higher-level cognitive function
- Stored in long-term memory for use in short-term memory PRN
Support for Motor Program Theory:
- Reaction time
- Deafferentiation
- EMG activity
Reaction time:
– Reaction time is longer when followed by more complex movement
= More time needed to organize system
– More elements or more limbs involved
– Example: finger lift followed by simple or complex sequence
– Deafferentiation
= Severing sensory nerves (no sensory input)
– Monkeys still able to perform learned activities (gross motor)
– Indicates sensory feedback not needed for motor program (open loop)
– Example: able to swing from branches but not do fine motor
- EMG activity
- Electrical activity same for muscles when limb movement is blocked
- No feedback from limbs (not moving) but program remains in muscles
Motor Programs:
- Attributes
- Roles
Attributes
- Specific muscles to perform action
- Order of muscle activation
- Proximal before distal (postural modifications first)
- Force of contractions
- Timing and sequencing
- Duration of contractions
Roles
- Define and issue commands
- Require commands (both for closed and open)
- Organize DoF of movement
- How body will move (sequence, timing, etc.)
- Make postural adjustments
- Proximal muscles first for stability
- Adapt reflexes for goal
- Reflexes used to correct movements
Central Pattern Generator
- Differences with motor program
- Examples
- Reflex reversal phenomenon
CPG = Centrally located control mechanism
- Produces repetitive, genetic movements; Triggered by stimulus (environmental input)
- Complex reflex reaction, but v. rudimentary motion
- Stimulation at level of cord, not cortical control needed
Difference with motor program:
- CPG = Genetically defined (NOT learned)
- Motor program = Learned activities; Developed w/ practice; Used to control learned activities
Examples:
– Locomotion in animals, Swimming in fish, Chewing in hamsters, Slithering in snakes
NOTE: Some elements of human gait, otherwise too complex for CPG only
Reflex reversal:
= Reflex response differs depending on phase of movement
Example:
– Pressure on dorsum of foot:
– Contact w/ surface (heel strike) = Stance phase»_space; Limb EXT (PF)
– Leaving surface (toe-off) = Swing phase »_space; Limb FLEX (DF)
NOTE: Increase stimulus causes increase motion
– Tactile cue during swing increases FLEX
– Tactile cue during stance increases EXT
Generalized motor program
- Definition
- Modifications
- “Surface features”
= General movement pattern stored in long-term memory
– Defines pattern of movement not specific movement
– Modified for use in specific movements
– Adapted to meet demands of task by selecting different parameters
– Selecting different parameters produces different surface features
NOTE: Solves problem of storage space
Surface features:
= Easily changeable components of movement pattern
– Result from changing parameters/constraints of movement
– Parameters set by demands of task
- Timing or speed (e.g., throwing fast or slow)
- Similar pattern of movement regardless of speed
- Change movement time while preserving fundamental timing structure
- Same timing and sequence of events that can run at different speeds
- Amplitude (e.g., writing large or small)
- Patterns of acceleration same for large or small movements
- Vary amplitude of movement by changing acceleration (force)
- Same movement structure just big or small
- Direction (e.g., throw left or right)
- Same movement structure directed high, low, R or L
- Limb and muscles used (e.g., writing on blackboard vs. check)
- Same movement structure w/ different effectors
Coordination:
- Definitions
- Temporal organization
- Scientific theories
Coordination
= Behavior w/ two or more DoF in relation to each other
= Organization of different elements of complex body/activity
– Produces effective, skilled activity
Temporal organization
= Timing or rhythms of movement patterns
– Different timing or rhythm increases difficulty
– Easier if beats are the same (even if out of phase)
Theories:
– Motor program concepts
– Discrete tasks of short duration (only open loop)
– Preplanning is critical, feedback is not
– Examples: flipping switch, swinging bat
– Self-organizing systems
= Movement pattern or rhythm dominates, regardless of intent
– Continuous, rhythmical tasks of long duration (closed and open loop)
– Examples: swimming, running, driving, walking
Reach-and-grasp
- Type of task
- Components
- Effects of:
- Moving block farther away
- Moving arm faster
- Closing eyes
- Adding second limb
- Adding limb w/ different movement
= Discrete, mostly open-loop
– Components
– Transport: Ballistic arm movement (temporal process)
– Grip-formation: Prepares hand to capture object
– Hand opens prematurely, Refines movement as it approaches object
– Widest grip at peak deceleration of arm (Spatial process)
NOTE: Temporal component coordinates movement
– Relative timing does not change despite speed or size of object
- Effects of:
- Moving block farther away
- Arm movement changes (has to go farther)
- Hand movement stays same (grip formation same) = Widest at peak deceleration
- Moving arm faster or closing eyes = Hand opens wider
- Compensates for anticipated error (increased spatial variability)
- Still widest at peak deceleration
- Adding second limb
- Difference distances
- Temporal measures same for both arms = Widest grip and grab objects at same time
- Slower than unilateral (More to preplan and more to coordinate)
- Closer limb slows down to match farther limb movement
- Adding second limb w/ complex movement
- Grasp object at same time
- Arm w/ simple movement slows or slightly mirrors complex movement
- Hard to temporally dissociate two arms (Pattern of complex mvmt detected in mvmt of other arm)
Human gait: Walking and running
- Type of task
- Triggers for shift from walk to run
Type of task:
- Continuous, self-organizing
- Two generalized motor programs (walk vs. run)
Triggers:
– Energy = Inefficiency in metabolic costs
– May be primary catalyst for transition
– Stability = Instability causes transition
– Increasing speed while walking COM shifts forward
– Limbs dissociate»_space; Transition to run
– Vision = Gait speed increases when perceived speed increases
NOTE: Most likely transition occurs based on multi-sensory inputs
NOTE: Self-selected walking speed most efficient (healthy people)
– Other factors may limit speed in impaired people (e.g., pain, fear)
Coordination in Continuous Tasks:
- Timing (in-phase vs. anti-phase)
- Speed (frequency)
- UE w/ LE
- Contralateral vs. Ipsilateral
- Direction of movement
Self-organizing basis
Timing:
– In-phase = same time
– Anti-phase = alternating
= Same kinematics (forces) and timing regardless
Speed:
– As speed increases stability decreases:
– Switch from in-phase to anti-phase
= System moves toward greater stability
Example: Alternating finger tap
– Switches to in-phase tap at 2.25 Hz
UE and LE:
– Easier to coordinate contralateral limbs
– Easier to coordinate movements in same direction
Example: PF (extension) and wrist extension w/ palm up
Self-organizing = systems moves toward stability
– Switch to in-phase as speed increases
– Easier to switch from anti-phase to in-phase
– Contralateral movements have less error
= Continuous actions modified due to decrease in stability
– Phase transition
– Changes basic form of pattern
Invariance or invariant features
- Relative timing
- Surface features
- Parameters
Invariance
= Constant characteristics of a movement
– Despite changes in surface features
– Relative timing ~ Fundamental timing structure of movement
– Ratios of durations of movement features
– Ex) Rel. contribution of ind. mm same regardless of movement time
NOTE: Applies to walking, running, reach and grasp
– Surface features
= Easily changeable components of movement
– Modified as a result of changing parameters
– Speed of movement
– Size of action (amplitude)
– Trajectory of movement
– Forces used to produce action
– Parts of limb used for action
– Parameters
= Variable inputs to a generalized motor program
– Same as above
Spatial accuracy
- Speed-accuracy tradeoff
- Closed vs. open loop
- Fitts Law
Spatial accuracy = Measure of variability in movement's endpoint -- Decreases with increases in (1) Movement distance (2) Movement speed (decreased time)
Speed-accuracy trade off
= Substitution of accuracy for speed or vice versa
– Closed loop: Accuracy is goal
– Time for feedback and correction during task
– Open loop: Speed is goal
– No feedback or correction during task
– Tradeoff applies to both open- and closed loop
Fitts Law
= Movement time (MT) linearly related to index of difficulty (ID)
– MT = log (2A/W)
A = movement amplitude (distance to target)
W = target width
– Changing size of target
NOTE: Applies to combined open- and closed-loop tasks
– Blend of programmed actions and feedback
– Initial part of movement is open-loop
– Later part involves error detection and correction (200-1000 ms)
Violations of Speed-Accuracy Tradeoff
- Timing accuracy
- Forceful movements
Timing accuracy
= Measure of variability in movement time
– Target time for task to take place
– End of movement occurs close in time to another event
***Variability INCREASES as MT INCREASES (speed decreased)
Force of movement
– Fastest but most forceful movement = less spatial variability
– Inverted V relation between force/MT and spatial error
– Highest force = fastest (shortest MT)
– Slowest and least forceful = lowest variability
– Second slowest at 50% max torque = highest variability
– Reason? Large forces (>70% max torque) have lower force variability
– Force production is more consistent for near maximal force
– Resultant trajectory is consistent spatially
NOTe: Limited number of studies, simple linear arm movements
Sources of Error in Rapid Movements
- CNS
- Reflexes
- Nerve impulses
- Muscle force
NOTE: Errors can occur at all points in system
CNS:
– Noisy or inconsistent central processes
– Converting nerve impulses to muscle contractions
– Movement planning processes (response selection)
– Stimulus identification
**Errors in commands for motor program
Reflexes:
– Contribute variability to muscle contractions
Nerve impulses:
– Errors in efferent and afferent signals despite same input
Muscle forces:
– Up to 70% max force force variability increases
– > 70% max force variability levels off and decreases near max
– Multiple mm contribute to single movement
– Error in any or all increases error in resultant movement
– Minimize # mm (degrees of freedom) to decrease error
– Minimize gravity
– Gait train on knees
Movement variability: Good or bad?
- Evidence for good
- Evidence for bad
– Depends on goal of task
Good:
- Postural sway in developmentally delayed children < normal children
- Ability to move COM outside BOS allows exploration of environment
- Post-concussion less variability in sophisticated measures of postural sway
Bad:
- Dysmetria:
- Finger-to-nose test for cerebellar injury»_space; Problems with endpoint accuracy
- Gaze instability:
- Overshooting saccades when trying to fix gaze on target
Theories of motor control (in brief)
- Reflex theory
- Hierarchical theory
- Motor programming theory
- System theory
- Dynamical action theory
- Ecological theory
– Reflex theory = All movements (simple or complex) due to reflex response
»_space; Clinical utility: Reflexes influence movement
– Hierarchical theory = Higher level CNS centers control lower levels
– Higher levels inhibit lower level reflexes; brain pathology»_space; persistent of primitive reflexes
– Motor program theory = Generalized motor programs for movement patterns
– Based on evidence (still used today):
– Still move without sensory input
– Similar patterns among individuals
– Several variations of patterns
– Complex movement from single stimulus
»_space; Clinical utility: Innate and learned programs do exist
– Focus on self-initiated movements, synergies, task and action (not discrete movements)
– Modify old programs for new skill (train new effectors or retrain old effectors)
– Systems theory = internal and external forces on body predict movement
»_space; Clinical utility: Physical properties of body predict movement kinematics
– Dynamical action theory = All movement is self-organized (no influence of CNS)
– Movements arise from demands of task and environment (physical principles, not neural)
»_space; Clinical utility: Manipulate environment to allow movements to self-organize
– Ecological theory (“Perception action”) = Perception of environment drives movement
– Emphasizes exploration and adaptability more than consistency in behavior
»_space; Clinical utility: Perception of environment can influence movement kinematics
– Ability may be impaired due to fear despite innate ability
