Ways of Researching the Brain Flashcards
What are the four ways of studying the brain:
- post mortem examinations
- functional magnetic resonance imaging (fMRI)
- electroencephalogram (EEG)
- event related potentials (ERP)
Post-mortem analysis:
ANALYSIS OF A PERSON’S BRAIN AFTER THEIR DEATH.
- Researchers study a person’s unique/ abnormal behaviour whilst they’re alive
- After death, analyse structure of the brain by comparing it to a neurotypical brain to ascertain which parts are not functioning well
- Helps researchers work out which part of the brain is abnormally structured
- Areas of the brain which are found to be damaged during PMA seen as correlated with abnormal behaviour
- If participant was not studied while they were alive (i.e. no primary data) data is gathered about their behaviour from secondary sources
What do researchers compare the brain to?
a neurotypical brain to ascertain which parts are not functioning well
If the ppt was not studied while they were alive, what data is gathered abt their behaviour?
secondary
Strength of PMA: allows for detailed examination of anatomical and neurochemical features compared to non-invasive methods such as fMRI.
This is bc you can physically assess the brain parts - unlike techniques like fMRI that can only visualise them as a diagram. This gives us precise info abt brain regions / neurochemicals involved in particular behaviours.
Increasing the validity of PMA
Strength Of PMA evidence: was crucial in building first understanding of key brain processes.
E.g Paul Broca used PMA to establish the link between language and brain by showing an area of the frontal lobe is related to language production.
Helped add scientific credibility to study of relationship between brain + behaviour / cognition which allowed for hypothesis testing using empirical evidence.
Increasing validity of PMA
Weakness Of PMA: data is retrospective.
If interesting findings r discovered in structure of brain during PMA, cannot follow up to gather further data on beh.
Also possible that damage to brain areas could be due to unrelated trauma or decay after death - could lead to inaccurate conclusions about which parts of the brain are linked to the abnormal beh
Weakness Of PMA: the sample sizes are generally small.
Small sample sizes and samples consist of unique patients - results cannot be generalised to the wider population.
Decrease validity
fMRI
functional magnetic resonance imaging
Functional Magnetic Resonance Imaging
fMRI BASED ON THE PRINCIPLE THAT THE MORE ACTIVITY IN AN AREA OF THE BRAIN -> HIGHER BLOOD FLOW TO THAT AREA OF BRAIN BC TO MAINTAIN HIGH ACTIVITY IN THAT BRAIN AREA: OXYGEN and NUTRIENTS ARE NEEDED TO BE SUPPLIED BY THE BLOOD
- fMRI scanners use magnetic field and radio waves to measure changes in blood flow + oxygenation caused by neural activity.
- Specifically measures change in energy released by haemoglobin - used to identify which areas are active and consuming more oxygen
- Scans are presented as 3D activation map - identify active brain parts + localised functions
- To identify activity, ppts go through an experimental task (e.g identifying faces) and the brain activity in response to the exp task is compared to the brain activity in response to the baseline task (e.g. looking at a cross)
- Areas with higher oxygen consumption = stronger brain activity. These show up as YELLOW/RED on the activation map.
What do fMRI scanners use to measure changes in blood flow and oxygen
magnetic field and radio waves
What realeases energy in the blood?
Haemoglobin
What are fMRI scans presented as:
3D activation map
What colour does higher oxygen consumption show up on the activation map as:
yellow / red
Strength Of fMRI: safer than some other scans.
Avoids the use of radiation (unlike PET), therefore is virtually risk free.
Moreover: it is non invasive and as it is virtually risk free - can be used more frequently while still providing a clear image of where brain activity is based
Increase validity
Strength Of fMRI: has high spatial resolution.
Since fMRI measures where changes in oxygenated blood flow happen - very good at identifying the exact source (location) of neural activity unlike techniques like EEG.
Typical scans can distinguish between activity of brain regions 3mm apart, however some high-resolution scans like fMRI can achieve this at a resolution of less than 1mm.
Strength Of fMRI: it provides both functional and structural info.
Helps us understand change in brain activity during tasks compared to PMA which only gives info on structure of the brain.
Moreover fMRI can measure deeper regions of the brain, e.g, amygdala, compared to EEG/ERP which measures areas near the surface only.
Weakness Of fMRI: poor temporal resolution compared to EEG.
As fMRI measures changes in blood flow - it is much slower than changes in neural activity and lags behind neural activity by several seconds - can make interpreting changes in activity caused by an event difficult.
Furthermore, quick changes in activity of brain (e.g ones that last 50ms) will not be detected/ differentiated well by fMRI.
Therefore, not effective technique for identifying when neural activity happens.
Weakness Of fMRI: expensive which leads to reduced sample sizes compared to EEG.
Bc of the reduced sample sizes (approx less than 25 ppts) - limits generalisability of the sample
Moreover, its expensive nature reduces accessibility to many researchers, making it inaccessible.
Electroencephalogram (EEG):
EEG MEASURES ELECTRICAL ACTIVITY IN THE BRAIN.
- This involves electrodes being placed on the scalp which detect small electrical charges resulting from neural activity occurring in brain cells.
- The number of electrodes planted are based on the areas of research.
Wider area = more electrodes
- These electrodes record signals from thousands of neurons directly under the electrodes - provides a measure of general activity of the brain
- Four patterns of electrical activity that EEG picks up on is: alpha, beta, delta and theta waves
Four patterns of electrical activity that EEG picks up on is:
alpha, beta, delta and theta waves
Strength Of EEG: has helped diagnose and research disorders.
EEG has allowed us to better understand brain activity that involves random bursts of electrical activity - helped develop an understanding of epilepsy + assist its diagnosis.
Moreover, EEG has helped further our understanding on sleep cycles by showing there are different brain waves in different stages of sleep.
Increases validity.
Strength Of EEG: high temporal resolution.
Unlike fMRI which has a delay between neural activity and blood flow- EEG has no delay between electrical currents and neural activity. EEG picks up quick changes in neural activity which happen each millisecond. Bc it has high temporal resolution - EEGs can help identify exactly when neural activity occurs
Strength Of EEG: cheaper than fMRI.
Leads to larger sample size + more affordable - increases generalisability of findings of studies where EEG was used. Makes EEG a more accessible method to researchers.
