Ways of studying the brain

How does functional magnetic resonance imaging work (fMRI)

It works by detecting changes in both blood oxygenation and flow that occur as a result of brain activity in specific parts of the brain

What happens when when a brain area is more active and what is the response known as

It consumes more oxygen, and to meet this increased demand, blood flow is directed to the active area - known as a haemodynamic response

What does fMRI produce images of and why is this useful

It produces 3D images showing which parts of the brain are involved in a particular mental process, helping us to understand localisation of function

What does an electroencephalogram (EEG) measure and how

It measures electrical activity within the brain via electrodes that are fixed to an individuals scalp using a skull cap

What does an EEG scan represent

The brainwave patterns that are generated from the action of thousands of neurons, providing an overall account of brain activity

What are EEGs often used to diagnose

Unusual arrhythmic patterns of activity which may indicate neurological abnormalities like epilepsy, tumours, or sleep disorders

What is the downside of EEGs

In its raw form it is a basic and overly general measure of brain activity

What is however in EEG data that researchers can make use of

Within the data are all the neural responses associated with specific sensory, cognitive and motor events that researchers have developed a way to isolate out

How do they isolate this useful data

By using a statistical averaging technique, all extraneous data is filtered out to leave only the responses that relate to, say, the presentation of a specific stimulus or performance of a specific task

What remains when all extraneous data is filtered out

Event-related potentials (ERPs) which are types of brainwave triggered by specific events

What are post-mortem examinations

A technique involving the analysis of a person’s brain following their death

Whose brains are most likely going to be subject to post-mortem examinations within psychological research

Those who have a rare disorder and have experienced unusual deficits in cognitive processes or behaviour in their lifetime

What parts of the brain are examined and why, and what is it compared with

Damaged areas as a means of determining the likely cause of the disease. Often compared with a neurotypical brain to assess the extent of difference

What is a strength of fMRI

Unlike PET scans it does not rely on the use of radiation. If done correctly it is essentially risk free, non-invasive and straightforward. It also produces images that have very high spatial resolution, showing detail by the millimetre - provides a clear picture of how brain activity is localised

What is a limitation of fMRI

It is expensive compared to other scanning techniques. It has poor temporal resolution because there is around a 5 second time lag behind the image on the screen and the initial firing of neuronal activity - means fMRI may not truly represent moment-moment brain activity

What is a strength of EEGs

Useful in studying the stages of sleep and in the diagnosis of conditions like epilepsy (characterised by random bursts of activity in the brain easily detected on screen). Unlike fMRI, EEG has extremely high temporal resolution. Todays EEG tech can accurately detect brain activity at a resolution of a single millisecond (and even less sometimes) - real world usefulness - ecological validity

What is a limitation of EEG

The generalised nature of the info received. The EEG is also not useful for pinpointing the exact source of neural activity. Therefore it does not allow researchers to distinguish between activities originating in different but close locations

What is a strength of event-related potentials

They bring much more specificity to the measurement of neural processes than could ever be achieved using EEG raw data. As they are derived from EEG measurements, they have excellent temporal resolution. This means they are frequently used to measure cognitive functions and deficits and the maintenance of working memory

What is a limitation of ERPs

Critics have pointed to a lack of standardisation in ERP methodology which makes it difficult to confirm findings. Also, in order to publish pure data in ERP studies, background noise must be completely eliminated, which can sometimes be challenging

What is a strength of post-mortem examinations

Vital in providing a foundation for early understanding of key processes in the brain. Broca and Wernicke both relied on post-mortem studies to establish links between language, brain, and behaviour. Post-mortem studies were also used to study HM’s brain to identify the areas of damage, which could then be associated with his memory deficits - continue to provide useful info

What is a limitation of post-mortem examinations

Causation. Observed damage to the brain may not be linked to the deficits under review but to some other trauma or decay. Another problem is that post-mortem studies raise ethical issues of consent from the individual before death. Participants may not be able to give informed consent, for example in the case of HM - challenges the usefulness of post-mortem studies in psychological research