Section 2 - Methods for studying motor behaviour Flashcards
What are the categories of performance measures
1) Performance Outcome
2) Performance production
Explain Performance outcome, measures/measurement device examples, and performance examples
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
Explain Performance production, measures/measurement device examples, and performance examples
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
What is the difference between motor skills and movement
section 1.3
What are the 3 most common ways of accessing movement
1) Movement error (or accuracy)
2)Movement magnitude
3)Movement time/speed (velocity)
What are the types of movement error
1) Constant error (CE)
2) Variable error (VE)
3) Root-mean-square error (RMSE)
Define Constant error, what type of error is it, what is its problem
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.
Define Variable error (VE), what type of error is it
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.
Define Root-mean-square error (RMSE), what type of error is it
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).
Describe difference in CE and VE diagram
refer to page 3
What is a way of measuring the movement magnitude
Root-mean-square (RMS)
Define Root-mean-square RMS, and why we use it
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
Define Reaction time (RT)
Time between the onset of a stimulus and onset of a response (not same as response Time)
Define simple-RT tasks
only one response choice available
Define Choice-RT tasks
Multiple choices are available and/or multiple stimuli may be presented
Define Movement time (MT)
Interval between the initiation of the response to the completion of the movement
Define response time
the sum of the RT and MT
graph on page 5
Define premotor RT and give an example
time for central processing
ex) perception of stimulus, decision making
Define Motor RT
- 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.
What are the major categories of Research Equipment/Techniques
1) Force plates
2) Motion capture cameras
3) Electromyography (EMG)
4) Eye tracking
5) Neuroimaging/Neurostimulation & neural recording equipment
what is the difference between equipment/techniques that record activity versus manipulate activity
manipulate activity: a stimulus is applied to a brain region/nerve/body part to alter activity
Explain Force plates & what are the used for
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).
Define Posturography
used to assess standing balance. Usually uses a force plate.
Can be used to administer the sensory organization test
Explain the sensory organization test
Manipulation across the 6 conditions create different conflicts between sensory information
Explain Motion capture cameras, Goniometers and accelerometers, IMU and what they are used for
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
Define Kinematic data
Kinematic data describes movement, independent of forces that cause the movement
Explain Electromyography and what its used for
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
explain head-mounted eye tracking and what it is used for
used to study movement
used to record eye movements
Explain microneuroghraphy definition and process and what its used for
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
explain - Neuroimaging, neurostimulation, and neural recording equipment
used to study nervous system activity and function (related to movement)
Explain single neutron recordings
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
Extracellular brain recordings and microstimulation:
explain extracellular recording
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.
Explain awake behaving vs anesthetized
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
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.
T
explain cell sorting
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
explain “analysis of neural activity” , “labelled line concept”
. 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.
explain electrical microstimulation
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.
Compare stimulation vs recording
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.
What are 3 technologies used to record brain activity noninvasively and explain them ( explain Neuroimaging to study brain activity)
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.
What are two types of noninvasive neurostimulation to study brain function
transcranial magnetic stimulation (TMS) transcranial electrical stimulation (tES).
Explain Transcranial magnetic stimulation (TMS)
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).
What can TMS - Transcranial magnetic stimulation be used for
*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)
What is Transcranial electrical stimulation (tES) and what are three types of it
- 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
Define Anode
an electrode, current enters brain FROM anode
Define Cathode
an electrode, current exits brain and flow TO cathode
Compare TMS (Transcranial magnetic stimulation) and tES (Transcranial electrical stimulation)
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
Explain difference in tES techniques
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
