BPK 207 Lec 2 Methods to Study Motor Behaviour

2 categories of performance measures

1. performance outcome measures (motor skills)

2. performance production measures (movement components)

list 2 examples of performance measures

time to complete a task - ex: time to run a mile

reaction time - ex: time between the gun and the runner’s beginning of movement

list 2 examples of performance production measures

displacement, velocity, joint angle, EEG

for joint angle - ex: angle of each joint in the arm when hitting ball

3 common ways to assess movement

1. movement error/accuracy

2. movement magnitude

3. movement time and speed

ways to quantify movement error/accuracy (3)

1. constant error (CE)

2. variable error (VE)

3. root mean square error (RMSE)

constant error (CE)

amount of direction of deviation from target

not equal to variability of error

variable error

the variability in the movement outcomes/scores

the standard deviation of the CE

describe the CE and VE for these diagrams

1. CE is small because most of the shots are within the black circle, which is the target. VE is large because the shots are very scattered among one another.

2. CE is large because the shots are far away from the target (black circle). VE is small because the shots are located very close to one another.

CE and VE provide what info to a coach

to correct CE, athlete needs to shift their position, thereby improving performance. VE harder to correct.

CE and VE are primarily for ___ skills

discrete (clear start and end)

root mean square error (RMSE)

overall error or spread of the movement across the duration of the performance.

used for continuous skills (no distinct beginning or end)

ways to quantify movement magnitude

root mean square

also many ways to quanity movement magnitude, like the distance a limb travels during a movement, the peak to peak differences in a signal, area under a curve, etc.

root mean square (RMS)

magnitude of the set of data across time

NOT SAME AS RMSE

why use RMS

detects the magnitude of a sine wave oscillating around zero when an average would give us a value of 0

ways to qualitfy movement time and speed

for reaction time paradigms:

1. Reaction time (RT)

2. simple -RT tasks

3. choice- RT tasks

4. movement time (MT)

5. Response time

reaction time

time between onset of a stimulus and onset/beginning of a response.

NOT same as Response Time

onset of movement or muscle activity

simple RT tasks

only one response choice available

choice RT tasks

multiple response choices available and/or multiple stimuli presented.

movement time (MT)

time between initiation of a response to completion of the movement

response time

sum of Reaction time (RT) and movement time (MT)

from the onset of stimulus and completion of response

premotor RT

time for central processing (perception of stimulus and decision making)

foreperiod

between when warning is made and onset of stimulus.

Motor RT

delay in onset of muscle activity or movement

types of equipment for studying movement

1. force plates

2. motion capture pictures

3. electromyography (EMG)

4. eye tracking

5. neuroimaging, neurostimulation, and neural recording equipment

force plates

embedded on a ground surface or on a moveable platform; measure kinetic data (forces that cause movement'/ physical properties of motion)

motion capture cameras

measure kinematic data (displacement, velocity during a movements)

electromyogrpahy (EMG)

record muscle electrical activity

eye tracking

head mounted systems that monitor eye movements

neuroimaging, neurostimulation, and and neural recording equipment

study NS activity and function related to movement

equipment vs technique

equipment= records activity

techniqye = manipulation of activity (ex: stimulus applied to brain to alter brain activity)

→ can be invasive/involve breaking of skin

force plates determine

how hard or fast a person loads a surface. also measures the COP.

COP (for force plates)

weighted average of all downward forces acting on the force plate

COP measures

postural sway

posturography

assesses standing balance usually with a force plate

computerized dynamic posturography (CDP)

platform with an embedded force plate and visual surround, Used for the sensory organization test (SOT). the force plate and the visual surround can move, which is manipulated to create conflicting sensory information

sensory organization test (SOT)

surround sway referenced

support sway referenced

surround sway referenced

visual surround moves in direct proportion to person’s away

describe the states for the visual, vestibular, and somatosensory system in this image

visual system detects no optic flow = not moving.

vestibular system detects head acceleration = moving

somatosensory detects change in muscle length, cutaneous receptors, joint receptors = moving

support sway referenced

force plate moves in direction proportion to person’s sway

describe the states of the visual, vestibular, and somtosensory systems

visual system detects optic flow = you are moving

vestibular system detects head acceleraton = you are moving

somatosensory system detects no change in muscle length, joint receptors, cutaneous receptors = not moving

when blindfolded, does the visual system determining if your moving or not moving

when visual system gone, it does not contribute to perception of movement.

motion capture cameras function

equipment that records kinematic data independent from the forces that caused the movement. Includes displacement, velocity, acceleration.

motion capture equipment purpose in reality

quantify movement for designing videogames and making movies

goniometers vs accelerometers

goniometers: record kinematic data, measure joint angles

accelerometers: record kinematic data, measure body/limb acceleration

electromyography function specifics

record electrical activity of muscles. electrode inserted into individual muscles and on skin above muscles

Head mounting eye tracking

equipment to record eye movements. Various different eye trackers, such as tracking path of gaze

Microneurography

technique that records the electrical activity of a single neuron’s axon within a nerve. Thin electrode embedded through skin, into nerve, and into nerve fascicles, where the electrode tip is on 1 or more axon sheaths of a neuron’s axon. The receptive field of the neuron is stimulated with a vibration.

applied to peripheral nerves

manipulate activity via vibration stimulus

describe this image

the electrical activity of a receptor when 30Hz vibration is applied to the foot. the receptor at row 2 encodes this frequency of 30Hz because (a) the spikes or action potentials occur at the same time with the peaks of the vibration stimulus, and (b) the spikes are the same shape, so the activity is from one neuron.

The receptor at row 4 does not encode at this frequency. The spikes of the receptor are inconsistent with the peaks of the vibration stimulus.

single neuron recording

extracellular recording (measures electrical activity outside the cell membrane) where an electrode is in the brain within 50 to 150 micrometres away from the neurons and requires cell sorting.

applied to cortical neurons

manipulates activity (similar technique to microneurography)

describe other forms of neuronal recording

awake behaving vs anesthetized recording and stimulation

awake studies examine how behaviour related to brain

both microneurography and single neuron recording use similar ____ techniques

cell sorting: microelectrode recording electrical activity of all cells witin 100 micrometers. Of the many neurons near the microelectrode, only a few of the neuron’s signals are strong enough to be isolated and studied as individual neurons. Typically the action potentials of the neurons align with some event.

all or none action potential meaning

action potentials all have the same shape and amplitude. Only the frequency and timing of action potentials is encoded.

labelled line concept

NS knows what info each neuron carries and what their firing pattern means.

T/F baseline frequency means smt

F. baseline frequency does not matter until theres a change in the baseline frequency of the neuron

electrical microstimulation

electrodes emit electrical current to neurons, artificially stimulating action potentials, which activate other neurons via neuron circuitry.

electrical microstimulation on the motor cortex

artificially stimulates muscle activity from different muscles depending on the region of the cortex.

stimulation vs recording

neural recording: provides info about neural function but doesnt alter it

electrical stimulation: uses electrodes to manipulate neural acticity

T/F stimulation is invasive, recording is not

neural stimulation and recording is invasive

neuroimaging is invasive, and manipulates activity

F. it is not invasive and records brain activity

name 3 neuroimaging technologies

1. functional MRI

2. MEG

3. EEG

T/F neuroimaging has high spatial resolution

low spatial resolution; records activity from many neurons

functional fMRI

measures local change in blood flow caused by brain activity

expensive

MEG

measures weak magnetic fields generated by brain’s electrical activity

cheaper than FMRI

EEG

electrodes placed on scalp that record electrical activity of brain

noninvasive neurostimulation techniques definition

study brain function of specific regions via enhancing, activating, or disrupting brain activity

list noninvasive neurostimulation techniques (2)

1. transcranial magnetic stimulation (TMS)

2. Transcranial electrical stimulation (tES)

transcranial magnetic stimulation (TMS)

technique where a stimulation coil is placed on head and generates a magnetic field that induces an electrical current in the brain, activating the axons of neurons

coil’s center has the strongest stimulation

describe TMS when stimulation coil over the hand region of the motor cortex

the stimulation coil generates a motor evoked potential (MEP)/activation of muscles in the hand, recorded by EMG. MEP is the electrical activity of the muscles.

TMS used to (5)

1. map connectivity of the cortex

2. map motor excitability of cortex

3. cause virtual lesions to study function of a region

4. assess the plasticity and recovery of function

5. rehabilitation of motor function

map connectivity in cortex

what TMS can be used for

stimulate a region see what other regions activated

map motor excitability in cortex

what TMS can be used for

excitability of motor map quantified by size of the motor evoked potential (MEP)

cause virtual lesions to study regional function

whatTMS can be used for

certain stimulation parameter can temporarily disrupt brain activity, like a stroke. Can test how this disruption affects specific tasks.

assess plasticity and recovery of function

what TMS can be used for

assessed via size of MEP

rehabilitation of motor function

what TMS can be used for

through repetitive stimulation, can help activate a brain a brain region so that its more plastic (more likely to recover after injury)

tES

transcranial electrical stimulation.

2 or more electrodes placed onto scalp to conduct electrical current in the brain

changes the membrane potential of neurons in the brain

TMS vs tES

TMS activates the axons of neurons.

tES changes the membrane potential or threshold of a neuron. does not directly activate cortical neurons

types of tES (3)

1. transcranial direct current stimulation (tDCS)

2. transcranial alternating current stimulation (tACS)

3. transcranial random noise stimulation (tRNS)

types of tES based on

differences in stimulation parameters (polarity/ the direction of current)

tDS polarity

tDS: polarity/direction of current doesnt change between electrodes

tACS

tACS: polarity/direction of current alternates like a wave between electrodes.

tRNS

tRNS: polarity/direction of current alternates.

describe the electrodes used in tES

anode electrode - current enters brain from anode

cathode electrode - current exits brain to cathode

anodal stimulation/cathodal stimulation - placed over brain area trying to modify

effect of tDS last up to ___

90 min depending on stimulation parameters and brain area.