ways of studying the brain Flashcards
fMRI - how they work
Measures blood flow in the brain when a person performs a task.
When an area of the brain is highly active, that area needs more oxygen and greater blood flow to provide this oxygen. By measuring blood flow and oxygenation, fMRI scanners enable researchers to identify which areas of the brain are activated during certain tasks.
fMRI - strengths
Non-invasive as does not use radiation or involve inserting instruments directly into the brain, therefore is risk free which allows more participants to have fMRI scans, helping psychologists gather further data on the human brain and therefore develop our understanding of localisation of function.
Good spatial resolution which allows psychologists to discriminate between different brain regions with greater accuracy. Therefore, psychologists can determine the activity of different brain regions with greater accuracy than other techniques.
fMRI - limitations
An expensive technique and will only gain a clear image if the participant is perfectly still.
Do not provide a direct measure of neural activity, therefore it is impossible to infer causation. While any change in blood flow may indicate activity within a certain brain area, psychologists are unable to conclude whether this brain region is associated with a particular function.
EEGs - how they work
Measure electrical activity through electrodes attached to the scalp. Small electrical charges that are detected by the electrodes are graphed over a period of time, indicating the level of activity in the brain. Often used to diagnose unusual patterns of activity and can indicate neurological abnormalities such as epilepsy.
ERPs - how they work
Use similar equipment to EEGs and measure brain waves. However are done by presenting a stimulus to the participant, and the researcher will look for activity related to that stimulus. The stimulus is presented many times to reduce any extraneous neural activity and the average response is graphed.
EEGs and ERPs - strengths
Non-invasive so risk free.
Cheap techniques so are readily available and allows more patients to undertake EEG/ERPs, which could help psychologists to gather further data on the functioning brain and therefore develop our understanding of different psychological phenomena, such as sleeping, and different disorders like Alzheimer’s.
Good temporal resolution - takes readings every millisecond, meaning it can record the brain’s activity in real time as opposed to looking at a passive brain. This leads to an accurate measurement of electrical activity when undertaking a specific task.
The limitations of EEGS are mainly addressed through ERPs as they are much more specific to the measurement of neural processes. This has led to their widespread use in the measurement of cognitive functions and deficits.
EEGs and ERPs - limitations
Poor spatial resolution so are unable to provide information on what is happening in the deeper regions of the brain.
Uncomfortable for the participant, as electrodes are attached to the scalp. This could result in unrepresentative readings as the patient’s discomfort may be affecting cognitive responses to situations.
Information gained is generalised so does not help pinpoint exact source of neural activity.
post mortem - how they work
Researchers will study the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage. This may involve the comparison of this brain with a “normal” brain. E.g. the work of Broca who examined the brain of a man who displayed speech problems when he was alive. It was discovered that he had a lesion in the area of the brain important for speech production. This later became known as Broca’s area.
post mortem - strength
Initially important in providing a foundation for early understanding of key processes in the brain - Broca and Wernicke both relied on post-mortem studies to improve medical knowledge and help generate hypotheses for further study.
Allow for a more detailed examination of anatomical and neurochemical aspects of the brain and enable researchers to examine deeper regions of the brain.
Successfully contributed to the understanding of many disorders - was found that schizophrenic people have higher concentrations of dopamine.
post mortem - limitations
Causation is an issue with these investigations as observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay.
Issue of ethical consent - people may not give consent to their brain being studied after they die.
There are many extranous factors that could affect conclusions: any medication a person may have been taking, their age, and the length of time between death and the post-mortem examination are all confounding factors that make the conclusions of such research questionable
