Ways of studying the brain Flashcards
(32 cards)
What does fMRI stand for?
Functional Magnetic Resonance Imaging
Define temporal resolution
The amount of time needed to acquire data
Define spatial resolution
The smallest feature a scanner can detect
What is a fMRI and what does it assume/ measure?
These indicates to the research which brain part are most active, they assume the most active parts require the greatest blood flow, so this technique can measure which brain parts use the most blood.
What is the method regarding fMRIs including the BOLD response?
-They measure the blood-oxygen-level-dependent response.
-When blood contains lots of oxygen it’s less affected by a magnetic field when it contains more oxygen it’s more affected by a magnetic field.
What are the two things fMRIs allow from the data collection?
— allows fMRI scanner to measure where oxygen rich blood and where blood low oxygen has come from.
— allows the ability to build a picture of the activity of different brain areas.
What are the 4 steps to the process of fMRIs? (Tasks, comparison, differences)
— ppts complete an experimental task while being scanned, compared to a scan on ppts doing nothing at all.
— tasks are often simple words / thoughts (e.g read swear words) as they are easy to do in the fMRI scanner
— Compares brain activity of Exp. task with control task
— Differences indicate which brain parts are active when completing exp. Task
What are the two strengths to fMRIs?
—They are non-invasive which doesn’t require radiation. Therefore they are ethically safe
—They have excellent spatial resolution + can identify small areas of activity in the human brain
What are the 6 weaknesses to fMRIs?
(Blood supply, concept, networks, cost)
—requires intensive training
— uses blood flow, which isn’t a perfect measure of activity in some brain areas, as some can have high activity with low blood flow
—unable to identify networks
— works slowly unlike ERP/ EEG, it tracks changes only over 1-2 seconds, not milliseconds
—concept of blood supply is an assumption
—very expensive ($10-20 MIllion) which means it has higher running costs then other techniques
What are the differences between MRIs and fMRIs?
MRI— scans every body part
FMRI— only scans the brain.
What does EEG stand for?
Electroencephalography
What are the 3 steps to the process of carrying out an EEG?
— when neurons fire, they create tiny electrical fields that can reach the scalp
—Electrodes are placed on a PPTS scalp with salt gel/glue to measure the changes in the electrical field.
—The signal is amplified, filtered and processes onto a computer. The computer then displays the changes in electrical charge as a line up and down.
What is the main concept of EEGs and what is an electroencephalogram?
‘ electric brain drawing ‘
It is a test used to evaluate the electrical activity in your brain.
What are EEGS used to see?
Used to see the occurrence of different types of electrical change, which is called a wave that has negative/positive peaks
What are the 5 waves an EEG tracks in the brain?
Gamma
Beta
Alpha
Theta
Delta
What do levels of each of the 5 following waves indicate within the brain?
-Gamma, Beta, Alpha, Theta, Delta
Gamma- indicate focused attention on a task
Beta- indicate ppt was engaged in thinking/completing a task
Alpha- found in posterior regions, indicate the ppt is awake/ very relaxed
Theta waves - indicate drowsiness / deep relaxation
Delta - indicates sleep
What are the 4 strengths to EEGs?
-good temporal resolution ( can measure what occurs very fast)
-Very useful in diagnosing conditions
- relatively cheap technique (100k - 300k)
- requires less training to learn how to collect analyse EGG data
What are the 2 weaknesses to EEGs?
-Only works for neurons that are close to the scalp, as signals from deeper regions of brain aren’t strong enough to be read by EEG
-EEG isn’t very accurate when it comes to spatial resolution as it is poor. Researcher may know when activity occurs but may not know its source.
What does ERP stand for and how do they differ/ compare to EEGs?
Event-related potential
They use the same technology as EEGs but with more electrodes/ extra stages of processing
What are the two uses of ERPs?
-Measure changes in electrical activity following a stimulus (e.g an angry face)
-Used to determine what the brain is doing millisecond per millisecond, showing the electrical wave of activity linked to the task.
What is the issue with ERPs?
Individual action potentials are too small to be measure due to the ‘noise’ from other neurons.
What are the 4 steps to the process of ERPs that aims to prevent noise/ turn the EEG into an ERP?
– The researcher will make recordings of 5 or more EEGs presentations of the same task. These recordings will show both the response to the task (always the same) and random noise from the brain.
–When the recordings are averaged together, the random noise will cancel itself out.
–The activity associated with the task is always there and so isn’t cancelled out.
–This leaves a “wave-form”, called an ERP.
What are the two types of peak that ERPs contain and how are these expressed as?
Provide examples for both
-Positive peaks are labelled with a ‘p’, E.g p100 is a positive electrical wave occurring around 100ms after the presented stimulus
-Negative peaks are labelled with a ‘m’, E.g n400 is a negative electrical wave that occurs around 400ms after presented stimulus.
What is the important peak for a positive electrical wave and why is this important?
p300 which occurs around 300ms after the stimulus
This indicates the ppt is experiencing surprise at the stimulus.
