Biopsychology - Methods of Studying the Brain Flashcards
What methods are there to studying the brain?
- psychologists use medical techniques to investigate brain localisation
- fMRI: highlights active areas of the brain
- EEG: shows overall electrical activity
- ERPs: brainwaves related to particular events
- post-morten examinations
How are medical techniques used to investigate brain localisation?
Techniques for investigating the brain are often used for medical purposes in the diagnosis of illness.
The purpose of scanning in psychological research is often to investigate localisation - to determine which parts of the brain do what.
How does an fMRI work?
fMRI detects changes in blood oxygenation and flow that occur due to neural activity in specific brain areas.
When a brain area is more active, it consumes more oxygen and blood flow is directed to the active area (haemodynamic response).
fMRI produces a 3D image showing which parts of the brain are active and therefore must be involved in particular mental processes.
How does an EEG work?
EEG measures electrical activity within the brain via electrodes using a skull cap.
The scan recording represents the brainwave patterns generated from millions of neurons. This shows overall brain activity.
EEG is often used as a diagnostic tool. For example, unusual arrhythmic patterns of brain activity may indicate abnormalities such as epilepsy, tumours or sleep disorders.
How do ERPs work?
ERPs are what is left when all extraneous brain activity from an EEG recording is filtered out.
This is done using a statistical technique, leaving only those responses that relate to the presentation of a specific stimulus or performance of a certain task (for example).
ERPs are types of brainwave that are triggered by particular events.
Research has revealed many different forms of ERP and how these are linked to cognitive processes (e.g. perception and attention).
What are post-mortem examinations?
A technique involving the analysis of a person’s brain following their death.
Areas of the brain are examined to establish the likely cause of a deficit or disorder that the person suffered in life.
This may also involve comparison with a neurotypical brain in order to assess the extent of the difference.
What are the strengths of fMRI?
A strength of fMRI is that it is non-invasive. Unlike other scanning techniques (e.g. PET), fMRI does not rely on the use of radiation and is safe.
Another strength is it produces images with high spatial resolution, showing detail by the millimetre. This means fMRI can provide a clear picture of how brain activity is localised.
What are the weaknesses of fMRI?
A limitation of fMRI is that it is expensive compared to other techniques and can only capture a clear image if the person stays still.
Another limitation is it has poor temporal resolution because of a 5-second lag between initial neural activity and image. This means fMRI may not truly represent moment-to-moment brain activity.
What are the strengths of EEG?
A strength of EEG is it is invaluable in diagnosing conditions such as epilepsy. EEG has also contributed to our understanding of the stages of sleep.
Another strength is that EEG has an extremely high temporal resolution. EEGs can detect brain activity at a resolution of a single millisecond.
What are the weaknesses of EEG?
A limitation of EEG is information is received from many thousands of neurons. The EEG produces a generalised signal from thousands of neurons.
Another limitation is it’s difficult to know the exact source of neural activity. EEG can’t distinguish the activity of different but adjacent neurons.
What are the strengths of ERPs?
A strength of ERPs is a very specific measurement of neural processes. ERPs are more specific than can be achieved using raw EEG data.
Another strength is that, like EEGs, ERPs have an excellent temporal resolution. This is especially so compared to fMRI, for example.
What are the weaknesses of ERPs?
A limitation of ERPs is the lack of standardisation in methodology between studies. This makes it difficult to confirm findings in studies involving ERPs.
Another limitation is that background noise and extraneous material must be completely eliminated. This may not always be easy to achieve.
What are the strengths of post-mortems?
A strength is post-mortems provided the foundation for understanding the brain. Broca and Wernicke both relied on post-mortem studies.
Another strength is post-mortem studies improve medical knowledge. They help generate hypotheses for further study.
What are the weaknesses of post-mortems?
A limitation of post-mortems is that causation may be an issue. Observed damage in the brain may not be linked to the deficits under review but to some other related trauma or decay.
Another limitation is post-mortem studies raise ethical issues of consent from the patient before death. Patients may not be able to provide informed consent (e.g. patient HM).
