Section 2 - Methods for studying motor behaviour

Question 1

What are the categories of performance measures

Answer 1

1) Performance Outcome
2) Performance production

Question 2

Explain Performance outcome, measures/measurement device examples, and performance examples

Answer 2

Performance outcome is 1 of 2 categories of performance measures

It relates to motor skills

Measures/measurement device examples: Time to complete a task ex) Reaction time RT, Amount of errors, time on/off balance, trials to completion

performance examples: Mile time, time to type, height of vertical jump

Question 3

Explain Performance production, measures/measurement device examples, and performance examples

Answer 3

Performance production is 1 of 2 categories of performance measures

It relates to movement components

Measures/measurement device examples: Displacement, Joint angle, Joint torque, EMG, EEG, PET

performance examples: Distance limb traveled/speed of limb while performing action, brain wave pattern while shooting an arrow, acceleration/deceleration pattern while moving

Question 4

What is the difference between motor skills and movement

Answer 4

section 1.3

Question 5

What are the 3 most common ways of accessing movement

Answer 5

1) Movement error (or accuracy)
2)Movement magnitude
3)Movement time/speed (velocity)

Question 6

What are the types of movement error

Answer 6

1) Constant error (CE)
2) Variable error (VE)
3) Root-mean-square error (RMSE)

Question 7

Define Constant error, what type of error is it, what is its problem

Answer 7

constant error is a type of movement error

definition: provides the amount and direction of deviation from the target (i.e., performance bias). Problem: Doesn’t consider amount of scatter/variability of error.

CE = å (Xi- T) , where Xi is the score on trial i, T is the target position, and n is the # of trials n
performed.

Question 8

Define Variable error (VE), what type of error is it

Answer 8

Variable error is a type of movement error

Definition: measures the inconsistency or variability in the movement outcome. It is basically the standard deviation of CE. CE and VE are often reported together.

Question 9

Define Root-mean-square error (RMSE), what type of error is it

Answer 9

Root-mean-square error is a type of movement error

measure of overall error. Gives an indication of the amount of spread of the movement across the duration of the trial/performance. CE and VE are primarily for discrete skills. RMSE is used for continuous skills, like in pursuit tracking (recall Section 1.8 Classifying Motor Behaviour).

Question 10

Describe difference in CE and VE diagram

Answer 10

refer to page 3

Question 11

What is a way of measuring the movement magnitude

Answer 11

Root-mean-square (RMS)

Question 12

Define Root-mean-square RMS, and why we use it

Answer 12

Quantifies the magnitude of a signal or set of data : NOT THE SAME AS RMSE
ex) displacement across time

RMS is one of several ways to get a sense of magnitude when an average might be misleading

Question 13

Define Reaction time (RT)

Answer 13

Time between the onset of a stimulus and onset of a response (not same as response Time)

Question 14

Define simple-RT tasks

Answer 14

only one response choice available

Question 15

Define Choice-RT tasks

Answer 15

Multiple choices are available and/or multiple stimuli may be presented

Question 16

Define Movement time (MT)

Answer 16

Interval between the initiation of the response to the completion of the movement

Question 17

Define response time

Answer 17

the sum of the RT and MT
graph on page 5

Question 18

Define premotor RT and give an example

Answer 18

time for central processing
ex) perception of stimulus, decision making

Question 19

Define Motor RT

Answer 19

• Reaction time can be based on the onset of movement (as in the figure from Schmidt & Lee 2005 above) or some other variable such as onset of muscle activity (in which case it would be just the Premotor RT). There is usually some delay between muscle activity onset and a measurable movement of the body; Motor RT is this delay period.

Question 20

What are the major categories of Research Equipment/Techniques

Answer 20

1) Force plates
2) Motion capture cameras
3) Electromyography (EMG)
4) Eye tracking
5) Neuroimaging/Neurostimulation & neural recording equipment

Question 21

what is the difference between equipment/techniques that record activity versus manipulate activity

Answer 21

manipulate activity: a stimulus is applied to a brain region/nerve/body part to alter activity

Question 22

Explain Force plates & what are the used for

Answer 22

used to study movement

Force plates : used to measure kinetic data (forces that cause movement)

Embedded in the floor, set of stairs, or on a moveable platform.

Force plates can be used to determine how fast and hard a person loads a surface. They can also be used to measure the centre of pressure (COP) (recall 1.6.1 Standing balance). COP is the location of the vertical ground reaction force vector, which is the weighted average of the location of all downward forces acting on the force plate. COP acts as a measure of postural sway (so can COM motion).

Question 23

Define Posturography

Answer 23

used to assess standing balance. Usually uses a force plate.

Can be used to administer the sensory organization test

Question 24

Explain the sensory organization test

Answer 24

Manipulation across the 6 conditions create different conflicts between sensory information

Question 25

Explain Motion capture cameras, Goniometers and accelerometers, IMU and what they are used for

Answer 25

Used to study movement

Used to quantify kinematic data (eg. during walking or reaching)

Motion capture cameras: often used to quantify movement for videogames/movies

Goniometers: records kinematic data, measures joint angles

accelerometers: records kinematic data, measures body/limb acceleration

Question 26

Define Kinematic data

Answer 26

Kinematic data describes movement, independent of forces that cause the movement

Question 27

Explain Electromyography and what its used for

Answer 27

Used to study movement

used to record electrical activity from muscles

indwelling electrodes:inserted into individual muscles

surface electrodes: places on the skin above a muscle of interest

Question 28

explain head-mounted eye tracking and what it is used for

Answer 28

used to study movement

used to record eye movements

Question 29

Explain microneuroghraphy definition and process and what its used for

Answer 29

used to study movement

technique to record electrical activity of single axons within a nerve

eg. to determine activity of an individual sensory receptor

A thin microelectrode is passed through the skin, into the nerve, and then into one of the nerve fascicles. Within a fascicle, small adjustments are made, placing the electrode tip next to 1 or more axon sheath(s).

page 9 for detailed diagram

Question 30

explain - Neuroimaging, neurostimulation, and neural recording equipment

Answer 30

used to study nervous system activity and function (related to movement)

Question 31

Explain single neutron recordings

Answer 31

improvements in
1)the ability to amplify very small electrical signals and (2) smaller electrodes, led to the ability to measure and record the activity of single neurons by the 1920s. This allowed for the first studies of receptive fields (Section 3a.3.4.4 and 3b.3.7) and later, tuning curves (Section 3b.3.8). Generally, the ability to isolate the activity of a single neuron is a powerful way to study how information is processed by the nervous system. Single neuron recording requires an electrode in the brain within 50-150 μm of neurons as well as cell sorting

Question 32

Extracellular brain recordings and microstimulation:

Question 33

explain extracellular recording

Answer 33

measures changes in voltage from outside of the cell membrane

note: microneurography (Section 2.4.6) is the same technique applied to peripheral nerves (the nerves that branch out from the brain and spinal cord), using similar electrodes and cell sorting techniques.

Question 34

Explain awake behaving vs anesthetized

Answer 34

Some recording and stimulating is done in anesthetized animals while other studies are conducted in awake animals. Awake preparations allow for the study of how brain function relates to behaviour but require electrodes and/or other hardware to be implanted on the head. Typically, a wire connects the implanted electrodes to amplifiers and a computer, but some wireless systems exist, e.g. for recording neurons in freely-flying bats

Question 35

T or F : there are no pain receptors in the brain, so animals (or people) don’t feel the electrodes in their brains, and it doesn’t hurt.

Answer 35

T

Question 36

explain cell sorting

Answer 36

A microelectrode will record all cells within ~ 100 μm – Each cell will have a slightly different waveform that must be isolated from the others.
– Typically, of the dozens of neurons close enough for an electrode to “hear”, only a few have signals strong enough to be isolated and studied as individual cells.
– This figure shows spikes from 4 cells that are different enough from each other and the background activity of many other cells to be isolated. The hundreds of spikes shown are all aligned to some event (and thus, there is much overlap in their profiles).
– Note similarity to action potential profile

Question 37

explain “analysis of neural activity” , “labelled line concept”

Answer 37

. Action potentials recorded from single neurons are all-or-none (Section 3a.3.2), which means their shape and amplitude, which remain consistent, carry no information. Only the timing and frequency of action potentials is important.

The nervous system uses spike timing/rate to encode information. For example, a neuron that encodes pressure on the skin might fire spikes at a faster rate as the pressure stimulus increases. But another neuron might fire fewer spikes with increased pressure. (The nervous system implicitly “knows” what the firing (or lack of firing) of each neuron means, just as it “knows” which neurons carry information about vision, and which about touch. This is the “labelled line” concept that we will cover in Section 3a.3.4.) What is important is a change in spike rate/timing. Indeed, many neurons have a spontaneous or “baseline” firing rate that means nothing until it changes, up or down. To analyze spike data, one can look for correlations between these changes in spike rates and events like sensory stimuli or behaviours. Such a correlation indicates that something about the event is “coded” by the neuron.

Question 38

explain electrical microstimulation

Answer 38

Using similar or identical electrodes in the brain, it is possible to pass electric current to local neurons (instead of recording the current generated by neurons). This can evoke action potentials in multiple neurons near the tip of the stimulating electrode. These artificially generated spikes then activate other neurons through natural brain circuitry. Regions like motor cortex (see Section 5b) are often mapped with electrical microstimulation, which evokes different muscle contractions from different parts of the cortical area. Stimulation of different parts of the hypothalamus can evoke feeding behaviour or simulate the euphoric high of illicit drugs; stimulation of sensory areas can alter perception.

Question 39

Compare stimulation vs recording

Answer 39

Neural recording is akin to fMRI, EEG etc.
- provides information about function but doesn’t alter neural function

Electrical stimulation via electrodes in the brain is akin to TMS, tES, etc.
- Doesn’t record neural activity but rather seeks to manipulate it. Stimulation and recording via electrodes in the brain are highly invasive.

Question 40

What are 3 technologies used to record brain activity noninvasively and explain them ( explain Neuroimaging to study brain activity)

Answer 40

These have lower spatial resolution, measuring the combined activity of thousands to millions to billions of neurons

• Functional magnetic resonance imaging (fMRI) = a method to visualize the activity of the brain; brain activity causes local changes in blood flow; fMRI measures the magnetic disturbance between oxygen-rich and oxygen-poor blood due to changes in neural activity. Requires large, very expensive equipment.

-Magnetoencephalography (MEG) = measures the very weak magnetic fields generated by the brain’s electrical activity; detects magnetic activity produced by thousands of neurons at a time. Requires large, very expensive equipment.

-Electroencephalography (EEG) = an array of scalp electrodes that record the electrical activity of the brain; signals come mainly from the cortex; uses comparatively cheaper equipment.

Question 41

What are two types of noninvasive neurostimulation to study brain function

Answer 41

transcranial magnetic stimulation (TMS) transcranial electrical stimulation (tES).

Question 42

Explain Transcranial magnetic stimulation (TMS)

Answer 42

This technique stimulates the brain through the scalp and skull. It doesn’t hurt

. A stimulation coil (two types are shown below) is placed on the head and generates a magnetic field (of similar magnitude to an MRI but of much shorter duration and spatial extent). The magnetic field induces an electric current in the brain, which causes activation of the axons of neurons. If you place the coil’s centre over the hand region of the motor cortex, you can activate muscles in the hand. When doing this, you generate a motor evoked potential (MEP), which is recorded by EMG and is shown in the figure below. A MEP is the electrical activity from the muscle (in this example, from a muscle in the hand). The size of this MEP can provide information about a variety of things (as you will see below).

Question 43

What can TMS - Transcranial magnetic stimulation be used for

Answer 43

*Map connectivity in cortex
E.g., stimulate one region and see what other regions are activated

*Map motor excitability of cortex
*The excitability can be quantified by the size of a MEP (among other ways)

*Certain stimulation parameters can temporarily disrupt a brain region, kind of like a very brief (and temporary) stroke. This is tested by measuring how TMS interferes with specific tasks

*Rehabilitate motor function
*Using a repetitive stimulation technique, you can facilitate activation of a brain region to make it more plastic (and thus more likely to recover after injury)

Question 44

What is Transcranial electrical stimulation (tES) and what are three types of it

Answer 44

• Transcranial direct current stimulation (tDCS)
• Transcranial alternating current stimulation (tACS)
• Transcranial random noise stimulation (tRNS)

These techniques use two or more electrodes on the scalp (e.g., saline-soaked sponges) to conduct electrical current into the brain.

Anode, Cathode

Question 45

Define Anode

Answer 45

an electrode, current enters brain FROM anode

Question 46

Define Cathode

Answer 46

an electrode, current exits brain and flow TO cathode

Question 47

Compare TMS (Transcranial magnetic stimulation) and tES (Transcranial electrical stimulation)

Answer 47

tES does not appear to activate cortical neurons directly
* Simply changes membrane potential (so that the brain region is more or less likely to activate)
– This is different than TMS, which activates neurons
* The effects of tDCS can last up to approximately 90 minutes depending on stimulation parameters and brain site

Question 48

Explain difference in tES techniques

Answer 48

The difference in the tES techniques is based on the stimulation parameters.

• all current vs time

tDCS: Line up, flat line, line down

tACS: Uniform waves up and down

tRNS: spikes