Ways of studying the brain Flashcards
AO1: intro
Over the years science and technology has led to the creation of a scanning techniques which have given psychologists an understanding of the function of the brain and the brain areas that are involved in behaviour.
What are the 4 ways of the studying the brain?
1) fMRI
2) EEG
3) ERP
4) Post mortem
What does fMRI stand for
Functional Magnetic Resonance Imaging
AO1: fMRI
fMRI works by identifying changes in the levels of oxygen in blood that occurs due to brain activity in specific areas. When a brain area is more active it leads to more oxygen being used so there is an increase of blood flow to this area.
This produces a 3D image showing which part of the brain is active, called an activation map.
Its used to identify which specific parts of the brain are active in particular mental processes (showing localisation)
AO3 fMRI (2)
fMRI is a much safer technique to measure brain activity than alternative methods. This is because it is non-invasive and doesn’t use radiation to identify the differences in brain areas. Unlike the use of PET scans which uses small amount of radiation, which despite being low levels, it could still lead to potential harm. Therefore, fMRI is a more appropriate technique as a way of studying the brain.
fMRI have higher spatial resolution than EEG and ERP which is an important feature of brain scans because it can accurately identify specific brain areas involved in behaviour, depicting detail by the millimetre and providing a clear image of how the brain is localised. However, fMRI has poorer temporal resolution as there is around a 5 second time lag behind the image on the screen and the initial firing of neuronal activity. Therefore, fMRIs may not truly represent moment-to-moment brain activity.
What does EEG stand for?
Electroencephalograph
AO1: EEG
EEG works by electrodes being placed on the scalp using a skull cap. It detects small electrical changes resulting from the activity of brain cells.
It produces electrical signals that are graphed over a period to see a person’s general brain activity.
Its used to detect sleep patterns and states such as sleep or arousal or to diagnose conditions such as brain tumours and epilepsy.
AO3: EEG (2)
A strength of the use of an EEG is that it is high in temporal resolution, this enables the researcher to take a real time recording of brain activity rather than a still image of the brain, as is the case with the use of an fMRI or post-mortem. This means that the researcher can gain a more accurate measure of general brain activity in a particular task. Therefore, providing a greater insight into the processes of the brain, such as the activity of the brain during sleep, increasing its validity as a way of studying the brain.
However, a limitation of the use of an EEG is that it is low in spatial resolution, therefore can only provide information on general activity in the brain. It cannot pinpoint the exact source of neural activity that is involved in behaviour, unlike the use of Event Related Potentials (ERPs) which enable a researcher to identify specific brain activity in a particular task. Therefore, findings may be less valuable in developing our understanding than by using alternative ways of scanning the brain such as ERPs.
What does ERP stand for?
Event related potentials
AO1: ERP
Like with EEG, electrodes are placed on the scalp, but an ERP shows the brains response to a specific stimulus. A stimulus is presented to an individual many times and their brain activity is measured in the same way as an EEG. However, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that link to the presentation of the stimulus.
They are graphed and a base line measure line is shown with a test line to the difference in brain activity to specific stimuli.
They’re used to study a range of cognitive processes such as attention, memory or perception in response to a specific stimuli.
AO3: ERP (2)
ERPs also have high temporal resolution, especially when compared to an fMRI. This means ERPs can identify brain activity every millisecond so researchers can see brain activity in real time. However, ERPs have poorer spatial resolution than fMRI as they can only detect brain activity in general brain areas rather than identify the specific location of brain activity.
It can be hard to obtain meaningful data from the use of ERP because they can be affected by external factors such as background noise which means that it can take many trials to obtain meaningful data as it hard to control these other factors. This limits the validity of ERPs as a means of studying the brain for a range of brain processes.
AO1: Post mortem
Post-mortems work by examining the brain of a dead patient and dissecting to see if there are any physical abnormalities. The brain can be compared with a brain that does not show this behaviour or mental process. It is mainly used on people who have a rare disorder or defects. When are they used?
One area of research has been the identification of Broca’s area as an important brain area for speech production.
AO3: Post mortem (2)
This is the only invasive way to study the brain which means that it is possible to get a more detailed examination of the brain than would be possible through solely using brain scanning techniques such as EEG and ERPs. For example, it has meant researchers have been able to study deeper areas of the brain such as the hypothalamus which has helped understand brain functioning in many different behaviours. Therefore, increasing the validity of post-mortems as a way of studying the brain.
However, is hard to establish cause and effect with post-mortem studies as there are many extraneous variables which cannot be easily controlled such as how long a person has had a particular disorder, age at time of death or whether they have received drug treatment for their disorder. This can make it more challenging to interpret the role of specific brain areas in behaviour. Therefore, it limits the internal validity of the findings of these studies and therefore the appropriateness of using post-mortems to study the brain.
