Introduction Flashcards
what does sensorimotor control include
how sensory information from the environment and body is used to plan and control movement
how the CNS coordinates muscles and joints to generate functional movement
how sensory, cognitive and motor systems, the tasks we perform, and the environment affect motor behaviour
how individuals adapt to different constraints imposed on movement, and how individuals learn motor behaviour
how injury affects movement and the ways which rehabilitation can improve function
motor behaviour
umbrella term
includes individual movements and motor skills
motor skill
a goal directed task that requires voluntary head, body and/or limb movement
made up of a series of movements - can be measured based on outcome and performance
ie/ shooting a basketball into a hoop (goal is to score)
adaptable and flexible
theres a variety of ways we kick a ball or shoot a hoop
movement
is a compound of a motor skill and is defined by the behavioural characteristics of the limb or a combination of limbs
ie/ extending at the elbow when shooting a basketball
behaviour of the actual body part
why do we distinguish movements from skills
people learn movements when beginning to learn a skill - people do things differently to achieve the same motor skill ie/ cooking an omlete - same omlete, but it is made differently
different movements can produce the same skill
- people adapt movement characteristics to achieve the same goal
- ie/ sometimes ppl bowl between legs at the beginning and then later learn to bowl with one arm
how are motor skills and movement measured differently
skills - related to the outcome
movements - relate to specific characteristics (ie/ kinematics like displacement, muscle activity)
feedforward control
deals with delays, planning ahead ie/ scheduling
uses sensory info prior to the execution of movement rather than during the movement
can use what was learned through trial and error from the previous movements
this type of control is often rapid
ie/ movement to swat a mosquito on your arm may be too fast for you to make corrections based on where you feel or see your arm
feedback control
uses sensory info (sensory feedback) during the execution of movement
involves modification of ongoing movement to produce high accuracy
allows for error detection and thus movemetn correction
this type of control is often slower
ie/ change your arm to catch a ball that is curving away because of the wind
degrees of freedom
refers to all the independent variables in a system
coordinate many bones/muscles to achieve a simple movement
ie/ each joint of the body can be positioned at a certain angle. each muscle can exert a specific amount of force. DOF are controlled by groups of neurons that can fire in different patterns
degree of freedom problem
relates to the fact that the nervous system must control (and coordinate) many neurons, muscles and joints to perform a particular motor behaviour
solution: ensures efficiency by avoiding extreme joint angles.
- uses muscle synergies
muscle synergies
group of muscles activated by a common command (thus working together) to perform a movement
serial order problem
relates to the fact that the nervous system must sequence a movement or series of movements
it must activate the correct muscles in the correct order
solution: nervous system plans
co-articulation
joint moving together seamlessly to achieve the movement
sensorimotor integration problem
translating coordinates from various sensory coordinate to one coordinate
also called the perceptual-motor integration problem
relates to the fact that the nervous system need to integrate sensory information (from a variety of sources) to form a perception, which it can then be used to act on
issue is sensory info is encoded by different receptors in different parts of the body and in different coordinate systems
motor learning problem questions
to what extent are we born with a selection of motor skills and to what extent of motor skills are motor skills learned?
how do we aquire skills that we must learn?
how do we adapt our movements to changes in the sensorimotor system?
how is motor memory represented and maintained?
what factors affect postural sway
physical characteristics and condition of the individual
- sway is usually increased with age and fatigue
stance posture
- position of feet can change amount of sway
support surface characteristics
- sway increases when standing on compliant terrain
availibility of sensory info
- sway is smaller when all three relevant sensory systems are available
psychological factors
- fear, multitasking
postural stability
refers to keeping the body’s center of mass within the base of support
centre of mass
is the point that is at the centre of the total body mass
- located roughly at your belly button
thought that the nervous system attempts to control the position of this activation of different groups of muscles to ensure balance
base of support
is the area of the body that is in contact with the support surface plus the space on the ground between these contact points
changes with foot position
centre of pressure
is the centre of the distribution of the total force applied to the supporting surface
- ie/ when standing on one foot and you lean to one side, you feel pressure on the bottom of your foot move to the edge of your foot. think of that as COP
helps keep (vertical projection of) COM inside BOS
anticipatory postural adjustments
this concept applies to any limb movement while standing or sitting and the initiation of walking
relates to the fact that the nervous system uses anticipation of what the task will require
small adjustments anticipating torques to achieve balance
postural changes (caused by changes in muscle activation) that occupy prior to (or at the same time as) the onset of the postural disturbance due to self-movement
purpose of APA (anticipatory postural adjustments)
to maintain equilibrium (postural stability)
stabilize the position of relevant body segments
meant to minimize the potential disturbance that the movement may cause. Remember if you move, you are moving your COM, which you must control
what is important for the brain to consider when reaching and grasping
location of the target
characteristics of target (size,shape,mass,texture,compliance)
initial arm/ shoulder configuration
components of reaching before the target object is grasped
transport of hand to object
orientation of the hand to align it with the orientation of the object
pre-shaping of the configuration of the digits and thumb in preparation to grasp the object
characteristics of reaching
straight-line hand paths to targets
unimodal, smooth, bell-shaped velocity profile of the hand
peak velocity and peak acceleration scale with movement amplitude
characteristics of grasping
progressive opening of the grip with straightening of the fingers followed by gradual closure
max grip aperture
- point in time which the thumb-finger opening is the largest
what part of the eye has the greatest density of cones and rods
retina (fovea) - best spatial resolution
saccade
used to get visual info
to move the eyes as quickly as possible to shift the fovea to a visual target in the periphery (fastest thing in body)
occurs up to 800/s
this ensures we get high resolution details about the object of interest
too fast to use sensory feedback during movement (so complete eye movements are planned in advance)
saccades are highly stereotyped; the distance of the target from fovea determines the velocity
smooth pursuit
keeps image of moving target on fovea
max: velocity up to 100/s
system is important to track moving objects, like a ball through the air
gaze shifts
involve coordination between the eyes and head
we have a neurological limit so the eyes do not stretch to much
motor behaviours emerge from the interaction of what factors
environment
task
individual
environmental factors
size, shape, speed of object
terrain
weather conditions
ambient lighting
ie/ obstacles
what are we ignoring in the environment
two types of task constraints
object interaction and stability
object interaction constraints
do you need to interact or avoid an object
how are we interacting (grasp,carry, hitting)
if interacting how much force is required
stability constraints
relates to base of support, as each requires a different level of control
stationary base of support
- sitting, standing
moving base of support
- walking
individual factors
cognitive, sensory and motor
cognitive related factors
includes attention, motivation and emotional aspects of behaviour
sensory related factors
integration of sensory input into meaningful info (to form a perception)
- sensory info provides info about the state of an individual body and environmental features
what is the limbs position at a given moment
which direction do i need to move and with what trajectory
motor related factors
many muscle joints to be coordinated
reflexive
involuntary coordinated stereotyped patterns of muscle contraction and relaxation elicited by peripheral stimuli
rhythmic
repetitive, can occur spontaneously or triggers by peripheral stimuli
voluntary
goal-directed movements that improve with practice as a result of feedback and feedforward mechanisms
what are the 3 one-dimensional classification systems
size of primary musculature required
specificity of where movements of skill begin and end
stability of the environmental context
pursuit tracking
experimenter-produced actions of the target and participants own movements are both displayed
- eyes track movement of object
compensatory tracking
experimenter-produced variations in the track are combined with participants movements to control a single cursor on a screen; participant must maintain this target value at some location
