Chapter 1: The Classification of Motor Skills
Skill: capactity to control our bodies – biological necessity
Degree of skill = ability to use movements
Motor skill performance influenced by:
Motor skill
Performance environment
Physical and psychological characteristics of the person performing the skill
Motor skills: activities or tasks that require volutantary control over movements of the joints and body segments to achieve a goal
E.g are the movements of the arms or legs cordinted in a similar or distinct ways whena person walks or runs at various speeds?
Motor Learning: the acquisition of motor skills, the performance enhandcement of learned or highly experienced motor skills or the reaqusition of skills that are difficult to perform or cannot be performed because of injury, disease, and the like.
Behavioural/neurological changes must occur as a person learns a motor skill and the variables that influence those changes
E.g feedback given- help or influence motor skill squsiiton?
Behavioural level:
Motor Deveolpment: the relationship between motor control and learning and human development from infancy to old age
How groth and maturation influence changes in motor beh for ex.
Old vs young for ex
Skills, Actions, Movements and Neuromotor Processes
Skill:
A. An activity or task that has a specific purpose or goal to achieve
B. An indicatior of quality of performance
A. The extent to which the person can consistencly schieve the goal of the task, (higher skilled more consistent to achieve the task goal)
B. The extent to which a person can achieve the task under a range of different conditions (more skilled = can deal w wider range of contions—richer repotorie of movements to draw upon in the different situions)
C. Degree of efficacy (more skilled = more efficient—solving problems, deploying info, muscular effort put into a task)
Purpose of a motor skill:
Cause some type of change in the environment or in the persons relation to the environment – purpose describes the problem & many different ACTIONS may be required to solve the problem
Multiplication= COGNITIVE SKILL (mental skill)
NOT a motor skill as it doesn't require manip over joints etc
COULD use your fingers to use the calc FOR MULTIPLICATION but NOT required – thus why it is a cognitive skill (but can USE motor in conjunction)
THUS – MOTOR SKILL = AN ACTION
Characteristics of skills and actions (motor skills)
1. There is a goal to achieve = have a purpose (action goal)
2. Are performed voluntarily: reflexes are thus NOT skills
Eye blink might involve movement and have a prupose but does NOT occur voluntary- this NOT a motor skill
3. Requires movement of joints and body segments to accomplish the goal of the task
4. Need to be learned, or relearned, in order for a person to achieve the goal of the skill
E.g walking- babies, strokes, knee/hip replacement et
Movements
Specific patterns of motion among joints and body segments
*Component parts of motor skills (the means by which action goals are accomplished or problems aree solved*
E.g LOCOMOTION is an ACTION
Action goal can be achieved used running, walking etc (specific pattern = movements)
Thus, variety of MOVEMENTS can accomplish same action goal*
Many to one relationship*
Can walk up the stairs in many different varities (skipping, one foot, speed etc) but at the end of the day = same goal was accomplished (got to the top)
One to many relationship*
One movement pattern could be used to acheiev many different action goals
E.g walking can be used to move the body from one location to another BUT CAN ALSO be used to MAINTAIN the body in one location if walking on a treadmill
*Even if context changes—same movement can be used to accomplish completely diff purposes*
PURPOSE ANY MOVEMENT FUFILLIS IS ENTERILY DETERMINED BY THE CONTEXT IN WHICH THE MOVEMENT OCCURS*
Neuromotor Processes
The mechanisms within the central and peripheral nervous system as well as the muscular system that underlie the control of movements and actions
Neuromotor process + movements = many to one and one to many relationship
E.g
Walking pattern can be maintained while fatigued by regulating the number and size of the motor units that are recruited as well as their firing frequency
Also, the motions of the joints and segments during each stride can be reproduced quite faithfully even though the motor units that are recruited might be quite different from stride to stride
Other hand – one to many*
A muscle might be activated in an identical way from one movement to the next but lead to a different movement if the context changes
E.g pectoralis major
Arm held out by side below horizontal, activation of this muscle brings arm back fo the side (adducts)
Arm is above the horizontal, the same activation of the muscle will bring arm closed to the head (abducts it)
INITIAL POSITION OF THE ARM DETERMINES THE RESULTING MOVEMENT**
Importance of distinguishing neuromotor processes, movements and skills
1. People learn actions especially when they begin to learn or relearn motor skills
Diff people may move in diff ways to achieve the same action goal (technique for ex)
2. People adapt movement characteristics to achieve a common action goal
Bcuz they differ in physical features that limit the movement characteristics they can produce to perform a skill (physical feature limitation)
3. People evaluate motor skill performance, movements and neuromotor processes with different types of measures
Motor skill performance: In terms of outcome (distance walked)
Movements: evaluated by displacements, velocities, and accelerations of the joints and body segments as well as the forces that cause these motions
Neuromotor processes: measured by activity in the nervous and muscular system
One Dimension Classification System
Motor skills can be classified by determining which skill characteristics are similar to those of other skills
*Categorize skills according to 1 common characteristic
This characteristic is divided into 2 categories, which represent extreme ends of a continuum rather than dichotomous categories
SO, thus a skill can be classified in terms of which CATEGORY the skill characteristic is MORE Like, rather then requiring that the characteristic fit one category EXCLUSIVELY
E.g using hot and cold (opposite ends BUT classify various temp levels according to this)
Three Motor Skill Classification Systems that use the one-dimension approach:
1. Size of Primary Musculature Required
Gross Motor Skills: Require large musculature
"Fundamental Motor skills" – walking, jumping, throwing etc
Fine Motor Skills: greater control of small muscls (esp hand eye coordination)
High degree of precision in hand and finger movements
Handwriting, typing, drawing
*LARGE muscles may be involved in performing a fine motor skill BUT the small muscles are the primary muscles INVOLVED in ACHEIEVING the goal of the skill
2. The Specificity of Where Movements of a skill Begin and End
Discrete motor skill: have a specified beginning and end location
Flipping light switc, hitting a piano key
*Specified plane in environment to begin and end movement*
Are usually simple, one movement skills
How we CONTROL movement
Continuous motor skills: skills with an arbituary beginning and end location
Steering a car, swimming, tracking a cursor, walking
End location is almost always arbitrary even if beginning has a location (walking for e.gx)
Movements are REPETITIVE
Serial motor skills:
A series or sequence of discrete movements
E.g playing a piece on the piano or shifting gears
Include the REPETIVE MOVEMENTS of contnious and the specified begiing and end in DISCRETE
3. The Stability of the Enviornmental Context
Enviornmental contex; the specific physical location where a skill is performed
Three features:
The supporting surface: which the perform perfoms the skill
The objects involved (in performing the skill)
Other people (involved in the performance situation)
E.g if a person is hitting a ball, the EC is the ball
Walking = Surface, prescence/absence of object and other people
Stability: weather the revelant EC features are stationary (stable) or in motion (not stable)
Stationary = CLOSED MOTOR SKILL
EC is thu stationary, = they DO NOT change locations during the performance of a skill
E.g picking up a cup from a table while you are sitting on a chair (supporting surface and object do not move)
Shooting arrow, climbing stairs, hitting ball off tee
**Important feature = the performer initates the movements involved in performing the skill when he or she is ready to do so = SELF PACED
Person does not have to adjust the movements to changing conditions while the performance is in progress
In motion = OPEN MOTOR SKILL
Enviornment has supporting surface, objects and or pppl moving when the performer performs the skill
Person must act according to these in motion*
= EXTERNALLY PACED
E.g surfacing a wave, catching thrown ball, walking on sidewalk with other people running
Movmement conditions must change when performing skill to adapt
Places more demand on the performer (monitor +adjust)
Gentile's Two Dimensional Taxonomy
TWO general characteristics of all skills (allows for complexity of skills to be considered)
1) The environmental context in which a person performs the skill
Regulatory conditions
Relevent env. Context features
*Those features of the enviornemnt context to which movements must conform if they are to acheieve the action goal
DO NOT REFER to char of a persons movmenets
ONLY to characteristics in the env context in which a skill is performed (size, shape, weight etc)
Intertrial Variability
Weather the regulatory conditions during performance are the same or different from one attempt to perform the skill to another
Either PRESENT or absetnt
Almost always PRESENT when env in motion
E.g walking thru a room many diff times, nothing changes = abset
Walking thru room, things change = present
If motion caused by a machine (treadmill etc) = ABSET
Non regulatory conditions
Colour, spectations, weather, day or night
Can influence performance but DO NOT DTERMINE movement characteritics*
2) Function of the action characterizing the skill
Function = weather o rnot performing a skill involves moving the body from one location to another, and whether or not the skill involves holding or using an object
Body orientation
Changing or maintaining of body location
A. body stability: skills that involve no change in body location during the performance of a skill, (standing, shooting an arrow, drinking from cup)
B. Body transport: active and passive changes of body locations
Walking (changing body location)
Standing on moving escalator (passive changing of body location)
Manipulation
Maintaining or changing the position of an object, (ball, tool, person)
Holding or using
Skills with this = more difficult to perfom (must do 2 things at once) – manipulate object + adjust body to accomdate for imbalance created by object
Practial Use of the Taxonomy:
Classifying skills provides insight into the demands that those skills place on the performer (early step in task analysis) – determine deficiencies/strengths etc
Can then become a tool to select a progression of functionally appropriate activities to help the person overcome their defictits and increase perofmance
Can chart indv progress of patients (rehab)
Chapter 2: The Measurement of Motor Performance
Performance outcome measures:
A category of motor skill performance measures that indicate the outcome or result of performing a motor skill
E.g how far a person walked, how fast you ran a distance
Based on the OUTCOME of the persons PERFORMANCE
Provide us with info about what happened at the level of actions, where the majr concern is weather or not the goal of the task was accomplished
Performance production measures
A category of motor skill performance measures that indicates the performance of specific aspects of the motor control system during the performance of a motor skill (limb kinetics, EMG etc)
Realte to PEROFMANCE characteristics that PRODUCED the outcome
Provide info that is relvant to the MOVEENT and NEUROMOTOR process levels of analysis
Reaction time: A Performance Outcome Measure
Most common measure indicating how long it takes a person to prepare and initate a movement
Interval of time between the onset of a stimukus (signal) and indicates the required ovement and the initation of the movement
DOES NOT INCLUDE ANY MOVEMENT RELATED TO A SPEIFIC ACTION – only the time time BEFORE movement begins*
The signal can relate to any sensory system & can be required to perform any type of movement
Used to assses "prep phase" to completing an action, and anticipation assessment
Movement time:
The interval of time between the initation of a movement and the completion of the movement
Begins when RT ends
Response time
Total time interval
Both RT and MT included*
BUT ONE DOES NOT PREDICT THE OTHER (independent)
Types of RT situations:
Simple RT
The reaction time when the situation involves only one signal (stim) that requires only one response
Lifting a finger from a key when light turns on
Choice RT
The reaction time when the situation involves more than one signal and each signal requires its own specified response
Red light, must lift index finger. Blue light, lift middle, Green, ring
Discrimination RT
The reaction time when the situation involves more than one signal but only one response, which is to only one of the signals, the other signal requires no response
Lift finger ONLY when red light come on. If blue or green do, do nothing
RT 2 Interval Components
EMG: the time in which a muscle shows increased activity after the stimulus signal has occred
1. Premotor time: time between the onset of the stimulus signal and the beginning of the muscle activity
Indicator of perceptual and cognitive decision aking activity in which the person engages while preparing an action
2. Motor time: period of time from the increase in muscle activity until the actual beginning of observable limb movmenet (muscle activity recorded here)
Indictes a time in lag in the muscle that it needs in order to overcome the inertia of the limb after the muscle receives the command to contract
Error Measures
1. Spatial Accuracy
Situations involving space dimensions, such as distance
2. Temporal Accuracy
Situtions involving time dimensions
3. Consistency problems
Lack in acquiring the basic movement pattern needed to perform the skill
4. Bias Problems
The person has acquired the movement pattern but is having difficulties adapting to the specific demands of the performance situation
Assessing Error for one-dimensional movement goals
Subtracting the achieved performance value from the target/goal amount
Absolute error: general indicator of how successfully the goal was achieved
Absolute diff between the actual performance on each rep and the goal
Provides us with the MAGNITUDE OF ERROR = general index of accuracy WITHOUT regard to the DIRECTION
Constant error: the signed (+/-) deviation from the goal
Provides the tendency to be direrectionally biased when performing a skill – measure of performance bias
Variable error: resprents the variability (or consistency) of performance
Standard deviation of the person's CE scroes for the series of reps
Assessing Error for Two Dimensional movement goals
Radical Error:
Assessing Error for continuous skill
Kinematic Measures
Kinematics: the description of motion without regard to force or mass (displacement, velocity and acceleration)
Displacement: describes changes in the spatial positions of a limb or joint during the time course of the movement
Kinetics: Force as a cause of motion Sep 21 2015
- Human movements organized by external and internal forces
- Importance of force: all 3 of Newton's laws of motion refer to force
1. Force is presented as necessary to start, change or stop motion
2. Force influences the rate of change in the momentum of an object
3. Force as being involved in the action and reaction that occurs in the interaction between two objects
- Angular force = Torque (rotary force)
- Effect of force on the rotation of body segments around their joint axes
- force: mass x acceleration (second law)
- Can show the effect on performance (e.g in swimmers – spreading of fingers during pullphase can improve propulsive forces
Muscle Activity Measures
- Electromyography (EMG): recording of muscle electrical activity
- Common use is to determine when a muscle begins and ends activation (Fig 2.10)
- Fractionated RT (index of movement prep)
Example**: Hamstring first activated if standing upright (holding body down upright) – arm go up; anterior deltoid
- Whole muscle Mechanomygraphy (WMMG):
- Displacement of muscle belly after stimulation
- Estimate muscle fiber composition within a single muscle
- Near infrared Spectroscopy (NIRS):
- Level of oxygen in the muscle (or brain) – (**at the time movement is occurring)
- Portable and can record while participant is moving BUT light probes cant penerate deep, provides info about outermost layer of brain, limited spatial resolution
Brain activity Measures
- Researchers + clinicians
- 4 measures commonly reported in motor learning + con research
- 1) EEG: Electrocephalography
- measures electrical activity in brain (waves)
- From fastest slowest: Beta, alpha, theta, delta (mental activities = fast) (sleeping = slowest)
- Active brain regions produce electrical acivity
- Seizures
-2) PET
- Neuroimaging (brain scanning) technique that measures blood flow in the brain
- Blood flow increases to active brain regions
-3) Fmri
- Neuroimaging technique that measures blood flow changes by deteching oxygenation levels WHILE person performs task (active = blood flow increases)
-4) MEG
- Measures magnetic fields created by neuronal activity
- Direct measure of brain function – can identify damaged brain tissue
TMS
- Transcranial magnetic stimulation
- Excites or inhibits activity in the cortex of the brain which causes a temp disruption of normal activity in the activity of the brain
- Figure of 8 coil (magnetic)
- Electricity goes through it
- Can induce stroke
- magnet of scalp
- Frontal cortex limb blood flow BLOCKED
- Can reverse current and increase neurong firing in brain
- Can help Parkinson's
Measuring Coordination
Asseses how one limb/joint moves relative to another
Quantiative measurement of angle-angle diagrams
Cross correlation technique fig 2.11
Measures the extent to which 2 joints follow a similar movement pattern
Relative phase
An idex of the coordination between 2 limb segments or limbs during the performace of cyclic movement
Inphase (0deg) relative phase
**Simultaneous flexion + extension of homologous muscles (0deg reative phase)
Antiphase (180deg) relative phase
** 0deg relative phase, simulatenous contraction of OPPOSITE muscles across two limbs
Faster you go = fatigue (more efficient for in phase so switch to that)
Chapter 3: Motor Abilities
Ability
A general trait or capacity of a person
Relatively enduring characteristic
A determinant of a person's achievement potential for the performance of specific skills (Indvidual difference)
Motor ability
An ability that is specifically related to the performance of a motor skill
Each person has a variety of motor abilities
Abilities as individual difference variables
Motor abilities establish achievement potentials for specific motor skills
Each motor skill requires specific motor abilities to successfully perform it
2 people have the same
Amount of practice
Leve and amount of instruction
Motivation to perform the skills THEN
** Motor abilities will influence the level of performance success each person can/will achieve!
2 hypotheses:
1) General motor ability hypothesis: many motor abilities are highly related and can be grouped as a singular, global motor ability
All Motor abilities RELATED to one another (general vs specific)
A person can be described as having an OVERALL amount of general motor ability = Singular, GLOBAL motor ability
The level of this ability in an individual influences the ultimate success that person can expect in performing ANY motor skill
E.g IQ (doesn't hold much prescedence in research however—appeal because it is intuitive)
2) Specificity of motor ability hypothesis: Many motor abilities are relatively independent in an individual (henry)
All motor abilities INDEPENDENT
Each person varies in the amount of each ability
A persons motor ability can be described only by a profile of amounts of each specific motor ability
**Research evidence supports this hypothesis**
E.g in Henrys study—Reaction time and Movement speed were UNCORRELATED (each is independent)
"All around athlete explanation" = they involve many foundational motor abilities in common – high performance since their athlethic abilities most likely are foundational to performance
Correlations between motor abilities
Each hypothesis predicts different correlation results – What are these different results?
Initial research compared RT and MT
Henry + colleagues (1960) showed LOW correlations
Generality of Specific Abilities Sept 23 2015
Recent evidence has investigated whether variations of a motor ability commonly seen as specific "actually represents ability"
2 examples:
1) Balance (AKA "postural stability" as a motor ability)
Two types
Static (w/o moving)
Dynamic (moving)
Static vs dynamic balance
Rose et al (2002): Children with CP showed balance problems while walking but NOT while standing
Drowatzy & Zuccato (1967): correlations among various tests of static and dynaic balance typically ranged from .03 to .26 (Table 3.1)
**Static and dynamic balance are distinct, independent abilities
*As a MOTOR ability- balance must be viewed as a MULTI-DIMENSIONAL ability (the ability to stand, sit or move without falling)
Static Balance alone: the maintenance of equilibrium while stationary (standing, sitting or kneeling)
Dynamic alone: the maintence of equilibrium while in motion (waking or running)
THUS – Static is not a "similar version"
E.g 14 of 23 children w gait disorders in CP showed normal STANDING balance char (they obvi cant stand)
Tests of balance include: Berg Balance Scale (14 tests of static and dynamic- predict falls in eldery or post stroke patients)
Timing as a motor ability
External vs internal timining
External: movement timining based on external source (externally-paced timing)
Eg stomp then clap
Hitting a moving baseball
Internal: Timing of movement based on persons internal repsentation of time (self paced timing)
"O canada example"
Walking or jogging at desired pace / dancer performing w o music but keeping a certain ryhytmn
2 Hypotheses: -- is this a motor ability?
1st view: Timing is controlled by a common timing process (like an internal clock) that provides the musculature with the rhythmic info needed to produce the continuous timing requirements of a skill
2nd view- The precise rhymtic timing we observe for the skills described results from TASK-SPECIFIC char related to the INTERACTION between the person and the performance environment
*Conclusion: research evidence indicates distinct timing abilities are skill specific (//task specific) rather than related to a general timing ability
E.g Low correlation between 2 tasks that require the same timing timing requirement – how well someone did on one of the two tasks did not predict how well they would do on the other!
E.g timining of 500msec for all 4 simple movements (tapping, vertical line, horixonal line circle)
Timing accuracy poor for all but tapping= SKILL SPECIFIC
Idenitifying motor abilities
Fleishman's Taxonomy of Motor Abilities
Described 11 perceptual motor abilities and physical proficiency abilities
PPA: more generally realted to GROSS motor skill performance = physical fitness ability to most (static strength, dynamic strength, explosive strength, trunk strength, extent flexibility, dynamic flexibility, gross body corrdination, gross body equi, tamina
Table 3.3 for list + definition
People differ in AMOUNT of each ability = Their motor abilities indicate limits that influence a person's potential for achievement in motor skill performance
Relating Motor Abiities to Motor Skill Performance
Motor Abilities are underlying, foundational compoents of motor skill performance
Task ananlysis can be used to identify the abilities that underlie any motor skill for ex.
Ex. In a tennis serve a person must perform certain COMPOENTS of that skill properly to be successfully (grip, stance, ball toss, backswing, forward swing, ball contact, follow through) – which represents the ability (multilimb coordination, control precision, speed of arm movement, rate control, aiming, static strength etc)
Uses for tests of motor abilities: used for a variety of purposes (bcuz of the foundational role played by motor abilitites in the performance of motor skills)
A. The prediction of future performance of a motor skill or phys activity (aptitude tests)
B. Evaluation (may involve eval of the causes of motor skill performance deficiencies or the assement of the effectiveness of an intervention program (rehab)
Chapter 4: Neuromotor basis for motor control
Concept: the neuromotor system forms the foundation for the control of movement
Intro:
The Neuromotor system:
Components of the CNS and PNS (makes muscles active- spine out to limbs) involved in the control of coordinated movement
Focus = CNS structure + function
The Neuron = NERVE CELL
Basic component of nervous system
Range in size from 4 to 100 microns
Provide the means for recieveing and sending info through the entire nervous system
General structure:
Cell body
Contains nucleus – Regulates homeostatsis of the neuron
Dendrites
Extensions from cell body: range from 1 to 1000's per neuron
Relase info from other cells
Many have none- thousands
Axon ("nerve fiber")
Extension from cell body – one per neuron with brances (known as collaterals)
Sends info from neuron
Ends of these = axon terminals (provide a signal transmission relay station for neurotransmitters) = chemical signals passed on to other neurons or to muscles (in movmenet control)
Covered by myelin – cell mem that speeds up the transmission of neural signals along the axon
Passing of neural signals from one neuron to another occurs at a SYNAPSE—junction between the axon of a neuron and another neuron
SAME
SA = Sensory – AFFARENT
ME = Motor – EFFERENT
Types and functions of neurons
Sensory neurons
"Affarent neurons"
Sends info to CNS from sensory receptors (Receive a naural signal and then covert it to an electrical signal that can be transmitted along the neural pathway and received by the CNS)
Unipolar- 1 axon: no dendrites
Cell body and most of the axon located in PNS – only axon control process enters CNS
Motor Neurons
Send neural impulses from the CNS to skeletal muscle fibers
"Efferent"
Alpha Motor neurons
Predominantely in spinal cord- (motor horn cells)
Axons synampse on skeletal muscles
Gamma motor neurons
In intrafusal fibers of skeletal muscles
Interneurons
Specialized neurons that origaniate and terminate in the brain or spinal cord (connector neurons)
Function as connections between
Axons from the brain + motor neurons
Axons from sensory nerves + spinal nerves ascending to the brain
CNS (brain + spinal cord combined)
4 structures most directly involved in the control of VOLUNTARY movement
Cerebrum
One of the components of forebrain
2 halves: right + left cerebral hemisphere
Connected by corpus collosum
Covered by cerebral cortex
Gray tissue: 2-5 mm thick
Ridges – gyrus
Grooves- sulcus
Cortex motor neurons
Pyramidial cells
Nonpyramidal cells
Fig 4.4
Cerebral cortex – Primary motor cortex Fri Sept 25th
The undulating, wrinkly, grey-colered surface of the cerrum; it is a thin tissue of nerve cell bodies (2-5 mm thick) called grey matter
Location and structure
Frontal lobe, just anterior to central sulcus
Contains motor neurons that send axons to skeletal muscles
Function:
Initation and coordination of movements for fine motor skills
Postural coordination
E/g finger movements for typing a piano key
Cerebral cortex- pre motor area
Location: anterior to the primary motor cortex
Functions include
Oganization of movements before they are initated
Ehythmic coordination during movent
Enables transitions between sequential movements of a serial motor skill (e.g keyboard typing, piano typing)
Contrl of movement based on observation of another person performing a skill
Planning of eye movements and orienting visual-spatial attention
Recieves a lot of info from sensory info of the brain (hear- then can do exact same pattern)
e/g for playing the piano (transitioning between movements)
Cerebral cortex- Suppulmentary motor area
Location: medial surface of frontal lobe adjacent to portions of the primary motor cortex
Functions:
Sequential movements
Preparation and organization of movement
Involved in coordinating 2 limbs (binomial coordination**) how limbs will move together
In phase and out phase with fingers
Cerebral cortex- partiel lobe
Patietal and frontal most important for movement control*
Location:
One of the 4 lobes of the cerebral cortex
Function"
Interacts with the premotor cortex, primary motor cortex and SMA BEFORE and DURING movement
Contols visual and auditory selective info, visually tracking a moving target
Cortical areas- anything on the outer portion of brain
Subcortical (under cortex) brain area important in motor control:
* Basal Ganglia
Buried within cerebral hemispheres
Every movement disorder is linked to this structure***
Recieves info from cerebral cortext and brainstem. Sends info to brainstem via thalmus & cerebral cortext
Consist of 4 large nuclei
Caudate nucleus
Putamen
Substantia nigra; black substance
Globus pallidus
Function involves control of :
Movement initation
Antagonist muscles during movement
Force
Parkinsons disease
Common disease associated with basal ganglia dsfunction
Lack of dopamine production by substantia niagra
Motor control problems (BART)
Bradykinesia (slow movement)
Akinesia (reduced amount of movement)
Rigidity of muscles
Tremor
Diencephalon – 2nd component of forebrain
Contains 2 groups of nuclei
Thalamus ** very important for movement control
Functions: a type of relay station- receives and integrates sensory info from spinal cord and brainstem; sends info to cerebral cortex (2 thamali)
Important role in control of attention, mood and perception of pain
*entrance point for ALL sensory info from the body- stops at the thalamus before it goes up anything futher, anything you taste smell etc
Hypothalamus (hypo = smaller)
Critical center for the control of the endocrine system and body homeostasis (temperature control)
Cerbellum
Also important in movement control
Location: behind cerebrum and attached to brainstem
"mini brain" "left and right halves, cortical covering of grey matter"
Structure includes:
Two hemispheres
White matter under the cortex contains:
Red nuelces – where cerebellum's motor neural pathways connect to spinal cord
Oculmotor nucleus (vision towards where you need it to move) through cererbrllo-thamamo-cortico pathway
Functions:
Involved in control of smooth and accurate movements
Clumsy movement results from dysfunction
Involved in control of eye-hand coordination, movement timing, posture
Serves as a type of movement error detection and correction system
Recieves copy of motor neural signals sent from motor cortex to muscles (efference copy) – involved in learning motor skills
Involved in learning motor skills
Brainstem
Location:
Beneth cerebrum; connected to spinal cord
3 components involved in motor control
Pons
Involved in control of various body functions (chewing) and balance control—links to cerebellum
Medulla
Helps coordinate physiological processes so we are able to perform the movement that we need (e.g breathing)
Regulatory center for internal physiological processes*
Reticular formation
Integreator of sensory and motor info; activates neural signals to skeletal muscles
*Not everything has time to get to the brain* eg pain stepping on class- get response from spinal cord to limb AS QUICK AS POSSIBLE (this is where that happens) – makes quick decision
The Limbic System
Parts of frontal and temporal lobes of cerebral cortex, thalamus and hypothalamus. And nerve fibers that interconnect these parts and other CNS structures
Funtion: learning of motor skills
& control of emotions and several visceral behaviours
Brainstem feeds into…
SPINAL CORD
Fig 4.5
Final delivery point for all motor input – initial point for recieveing sensory info
A complex neural system vitally involves in motor control
Structure
Grey matter- H shaped central portion
Consists of cell bodies and axons of neurons
Two pairs of "horns"
Dorsal (posterior) horm; cells transmit sensory info
Ventrual (anterior) horns; contain alpha motor neurons with axons terminating on skeletal muscle
Intereurons (Renshaw cells)- in ventral horms
Connector neurons
Some cases, we need neurons that are going to receive a message and say it needs to go somewhere else as well e.g stepping on glass – get a message for the "ouch get off" and need a message to get to other leg to not hit ground AND to arms to keep balance (connector neuron allows this to happen)
Sensory Neural Pathways Wed Sept 30th 2015
Several Neural tracts (ascending tracts)
Pass through spinal cord and brainstem
Connect to sensory areas of cerebral cortex and cerebellum
2 tracts to sensory cortex especially important for motor control
Dorsal column (comes from proprioceptors) & touch and pressure
Anterolateral system (pain/temperature)
Tract to cerebellum important for motor control
Spinocerebelluar tract: primary pathway for proprioceptive ingo
Tract from spine to cerebellum*
Cross at the brainstem from one side of the body to other; thus sesnsory info from one side recieveed on the other!
For movement; 2 tracks originate in arms and neck, 2 in trunk and legs
Motor Neural Pathways
Called descending tracts
Travel from brainstem through spinal cord
Both tracts work are FUNCTIONALLY DEPEDENT on one another for movement* & these pryramdial lines indicate that the muscles on each side of the body are controlled by the opposite cerebral hem
Pyramidial tracts (corticospinal tracts)
60% from motor cortex
Most fibers cross to other side of body (decussation) in medulla of brainstem
Involved in control of fine motor skill perofmance
Nonpyramdial tracts (brainstem path)
Fibers do not cross to other side of body
Individual in postural control and control of hand and finger flexion-extension
Extrapyramdial tracts (brainstem pathways)
Have their cell bodies in the brainstem w axons descending into spinal cord.
DO NOT cross over to opposite side of body
Involved in postural control as well as facilitation and inhibition of muscles (flexion/extension)
The Motor Unit
An alpha motor neuron and all the skeletal muscle fibers it innervates
When a motor neuron activates (fires) all its connected muscle fibers contract
Neuromuscular junction allows nerve impulses to tracel (between alpha motor neuron and skeletal muscle fibers)
The ultimate end of the motor unit neural info
~200,000 alpha motor neurons in spinal cord
# of muscle fibers served by a motor unit depends on the type of movement associated with the muscle
Fine movmenets (e.g eye = 1 fiber (motor unit))
Gross (e.g postural control = many fibers)
Motor Unit recruitement
Amount of force generated by muscle contraction depends on the # of muscle fibers associated
To increase force, need more motor units
Process of increasing # of motor units involved = RECRUITEMENT
Recruitment follows "size principle"
Size = mptor neuron cell bdy diameter
Size principle = recruit smaller motor units first (i.e the weakest force produced) then systematically increases size recruited until achieve desired force
FIG 4.7
From intent Action: The nural control of vol movement
*Think about the entire process of decding to perform a skill and actually preforming it
The neural activity involved in this process typically follows a heirarchial org. pattern
From high to low levels of neuromuscular system
Carson +kelso (2004)
Demonstrated: we know less about which brain structures involved in which type of movements than how we control movement
*Cognitive intention is a critical component
Experiment:
Part. Performed finger-flexion movement to a metronome
On the beat (synchronize) – Activate contralateral sensorimotor cortex, SMA. Ipsilateral cerebellum
Between beats (syncopate) – premotor, prefrontal. Temporal association + basal ganglia
Task involves exactly the same movement 2 different cognitive intentions
FRMI results showed:
Diff brain regions active for the 2 movement intentions
Chapter 5: Motor Control Theories
*Actions are continuously adapted to the environment*
Theory and Pro Practice
What is a theory?
Accurately describes a large class of observations
Makes definie predictions about results of future observations
Motor learning and control theories focus on:
Explaining human movement behaviour
Provide explanations about why people perfom skills as they do
How does a theory have relevance?
S.I*not testable
Motor control theory
Describes and explain how the nervous system produces coordinated movement during motor skill perofmance in a variety of enviornments
2 important terms:
Coordination
Patterning of body and limb motions relative to the patterning of environmental objects and events
2 parts to consider:
Relations among joints and body segment at a specific point of time
Relation between pattern of corrdition and the environment so the action can be accomplished
Degree of freedom problem
Degree of freedom: # of independent elements in a system and the ways each element can act
Degree of freedom problem: how to control the df to make a complex system act in a specific way
The control of a helicopters flight
For the control of movement:
How does the nervous system control many df of muscles, libs, joints to enable a person to perform an action as intended?
2 general types of control systems Oct 2nd 2015
See notebook for drawing
Open + Closed loop control system
Incorporated into all theories of motor control
Show different ways the CNS and PNS iniate and control action
Each has a central control center (executive)
Function to generate + forward movement instructions to effectors (i.e muscles)
Each includes movement instructions from control center to effectors
Content of the intructions different between systems
Differences
Open loop:
Does not use feedback
Control center provides all the info for effectors to carry out movement
Closed loop:
Uses feedback
Control center issues info to effectors sufficient only to initate movement
Relies on feedback to continue + terminate movement
2 Theories of Motor Control
Motor-Program Based theory:
Memory-based mechanism that controls coordinated movement
Dynamical systems theory:
Emphasizes the role of info in the environment and mechanical properties of the body and limbs in movement control/coordination
Motor program based theory
"Schema Theory" by Schmidt (1988)
Generalized motor program (GMP): Hypothesized memory based mechanism responsible for adaptive and flexible qualities of human movement
Proposed that each GMP controls a class of actions, which are identified by common invariant characteristics
GMP function: to serve as a basis for generating movement instructions prior to and during the performance of an action
Characteristics
Invariant features:
Characteristics that do not vary across performances of a skill within class of actions
The identidying sign of a GMP
Paramaters
Specific movement features added to invariant features to adapt to a specific situation
Characteristics can vary from one performance of a skill to another
Invariant features & Parameters:
E.g of in feature: relative time of the components of a skill (i.e % of total time compomenet)
E.g of a parameter: overall amount of time take to perform a skill
An analogy from music/dance
Relative time = ryhtmn (beat) of the muscle (e/g the 3 beats to a measure for a waltz)
Overall time = tempo (the speed which you waltz)
Regardless of how fast or slow a waltz, the ryhtmn reains the same = INVARIANT
Testing Relative Time Invariance
Shapiro, Zernicke, Gregor and Diestel (1981)
Used gait characteristics to test prediction of relative time invariance for a class of actions controlled by a GMP:
Are walking and running 1 or 2 classes of actions
Assesed 4 compoents of 1 step cycle
Calculated relative time for each component at 9 speeds (3-12 km/hr)
Relative time = % of total time for each component in 1 step
RESULTS
Relative time similar within speeds when walking but diff from speeds when running (similar whithin speeds when running)*
Dynamical Systems Theory
Describes the control of coordinated movement emphasizing the role of environmental info and dynamic properties of the body limbs
Began to influence views about motor control in each 1980's
Views the process of human motion control as a complex system that behaves like any complex biological or physical system
Open + Closed loop control systems
Incorporated into all theories of motor control
Show different ways the CNS and PNS initate and control action
Each has a central control centre (executive)
Function to generate + forward movement instructions to effectors (i.e muscles)
Each includes movement instructions from control center to effectors
Content of the instructions differ between systems
Concered with identifying laws (natural and physical) that govern emergence and change in human coordination patterns
Concepts based on Non-linear Dynamics
Behaviour changes are not always continuous. Linear progressions but are often sudden or abrupt.
Behaviour is organized by the interactions among task, environmental and organismics constraints
Behaviours self organized in response to constraints
Attractors
Attractor: a stable state of the motor control system that represents preferred patterns of coordination (walking)
Characteritictis:
Identified by order paramters (e.g relative phase)
Control parameters (e.g speed) influence order paramerts
Min trial to trail performance variability
Stability remains present state despite perturbation
Energy efficient
Order and Control Parameters
Order parameters:
Also called collective variables
Variables that define the overall behaviour of the system
Enable a coordinated pattern of movement to be distinguished from other patterns
Relative phase is the most prominent order parameter it shows how 1 joint/segment moves relative to another
Control parameters:
A variable, when increased or decreased, will influence the stability and character of the order parameter
Is important to identify since it becomes the variable to mainipulate in order to asses the stabilitu of the order parameter
Provides the basis for determining attractor stage for patterns of limb movements
Self-organization
Behaviour that emerges in response to a particular set of constraints
No one constraint is any more important than another in determine how behaviour is organized
Self-organizaiton Oct 5th 2015
Behaviours that emerges in response to a particular set of contraints
No one constratint is any more important than another in determining how the behaviour is organized
Ex. Gait transitions
A person begins alking on treadmill at a slow speed
Treadmill speed (control parameter) increases gradually
Person shifts to running at a certain speed (not same speed for all people)
Same effect if person begins running on treadmill-shifts to walk at certain speed
Swim Skate Transitions
Each trial involved a swim velocity increasing (began at preferred velocity)
Arm-stroke analysis showed 2 distinct patterns of arm coordination
Began in one mode but abruptly began 2nd mode at aa specific swim velocity
Coordinate Structures (Muscle Synergies)
Groups of muslces (and joints) constrated to act as functional units
If a perturbation stops one set of muscles from working, another automatically compensates
E.g walking w a leg in a cats
Deveolp through practice, experience, or naturally
Perception-Action Coupling – related to dynamic system theory
The linking together (i.e coupling) of info and movement
The perception part
The detection and utilization of critical info for the control of action
The action art
The various movements that are regulated by perceived info
Example—TAU
When walking, the time to contact an object in your pathway (specificed by the perceived rate of change of the object's size) determines when you initiate stepping over the object
I.e your stepping action is "coupled" with your visual perceptuon of the object
Affordances
Possibilities for action
The reciprocal fit between charactiericts of the person and the enviorbment that allow certain actions to happen
E.g the ratio of leg length to stair height determines whether a set of staris is climbable
Present state of the control theory issue
Currently, both the motor program based theory and dynamical system theory predominate
Research investigating each has shown that a theory of motor control cannot focus exclusively on ovement information specified by the CNS
Task and enviornmal characteristics must also be taken into account
Speculation exists that hybrid of the 2 theories as a compromise theory could emerge to explain control of coordinated movement
Chapter 7: Speed Accuracy Skills Oct 5th Cont.
When both speed and accuracy are essential to perofm the skill, there is a speed accuracy trade off
I/e when speed is emphasized, accuracy is reduced and vice-versa
Motor skills that require speed and accuracy? i/e texting
Square ex—less distance (d) Size of target (w) increase = faster
Fitts Law
MT for speed accuracy skills
Movement distance – Target size
MT = a +b log2 (2D/W)
(Index of difficulty): log2 (2D/W)
Application to non lab skills
Dart throwing
Peg board manipulation (used in physical rehab + training)
Reaching/grasping container
Moving curser on comp
Speed-accuracy skills: motor control proceses
Open loop control
At momevemt initation
Moves limb to vicinity of target
Closed loop
At movement termination
Feedback from vision and proprioception needed at end of movement to ensure hitting target accurately
Role of vision depends on MVT phase
Prep phase:
Asses regulatory conditions of enviornmenta cortex
Initial flight phase:
Motor limb displacement and velocity; shift gaze to keyhole at 50% time to contact
Termination phase:
Provide spatial termporal to correct movement accuracy errors to ensure insertion of key
Prehension (reaching + grasping)
3 comp:
Transport: movement of hand object
Grasp: hand take hold of object
Object manipulation: hand carrying out intended use for the object
E.g drinking from it, moving it to another location
Research Demonstrating temporal relationship of reach and grasp Oct 7th 2015
Goodale and colleagues
Object's size influences:
Timing of max griup aperture
Velocity profile of hand transport movement
Regardless of object;s size or distance
Mx grip aperture occurs at 2/3 movement time
Other research shows:
Relationship of movement kinematics for prehension phases ememplify characteristics of a "coordintive structure"
Role of Vision in Prehension
Prep and initation of movement
Assesses regulatory condtions
Transport of hand to object
Central vision directs hand to object- provide time- to contact info to initate grasp
Perpiheral vision provides hand movement feedback
Grasp of object
Supplements tactile and proprioceptive feedback to ensure intense use achieved
Prehension and Fitt's Law
Prehension demonstrates speed accuracy trade off characteristics predicted by Fitt's law
Object width = target width
Index of difficulty for grasphing containers of different sizes and quanities of liquid
Deveolped by Latash & Jaric (2002)
See A closed look in text
Critical component is % of fullness
Ratio of mug size and liquid level
Handwriting
Diff motor control mechanisms involved with what people write + how they write
Much individual variation in limb movement
Motor equivalence
People can adapt to various context demands
Handwriting motor control demonstrates characteristics of a COORDINATED STRUCTURE
Vision and Handwriting
Fig 7.3 text
Bimanual Coordination
Motor skills that require simultaneous use of two arms
May require two arms to move with the same or different spatial (location/distance) and/or temporal characteristics (timing)
Symmetric bimanual coordination
Asymmetric bimanual coordination (antiphase)
Two arms prefer to move symmetrically
Research demonstrates temporal and spatial coupling of the two arms when initially performing asymmetric bimanual skill
With practice, a person learns to dissossciate the 2 limbs as needed to perform the skill
Catching a moving Object
Three phases
Initial positioning of arm and hand
Shaping of hand and fingers
Grasping the object
Evidence
Successful ball catchers initated final hand and finger shaping 80 msec earlier than non-catchers
Amount of visual contact time needed to catch a moving object
Two critical time periods
Initial flight portion ---- specific amount of time was not known
Just prior to hand contact
Between the two critical periods
Brief, intermittent visual snapchots sufficient
Striking a Moving Object
Ball speed effect
Skilled strikers demonstrate similar bat movement time for all ball speeds, change amount of time before initating bat movement
Visual contact with moving ball
Skilled strikers do not maintain visual contact with ball throughout ball flight but visually jump from early slight to predicted striking location
Location
Central pattern generators (CPG) in the spinal cord involved in the control of locomotion (i.e gait)
Provide basis for steryotypic rytmiticity of walking and running gait patterns
But, proprioceptive feedback from muscle spindes and GTO's also influence gait
Locomotion
Spontaenous gait transitions
An important characteristic of locomotion (ch 5)
People sponenteously change from walking to running gait (and vice versa) at critical speed (specific speed varies across people)
Why do spontenaous gait trasnitions occur?
Various hypothesis
Most popular: minimize metabolic energy use
Some agreement that one factor responsible
