B6 - ways of studying the brain

Question 1

Functional magnetic resonance imaging (fMRI)

Answer 1

Technique used for measuring changes in brain activity while a person performs a task, this is done by measuring changes in blood flow (indirectly measuring electrical activity of neurons)

When a specific area of the brain is active, more oxygen is used to meet the increased demand, therefore an increase in blood flow is found in the active area

3D images are produced which shows what specific parts of the brain are involved in certain mental processes

FMRI scanning has helped develop our understanding of localisation of functioning

Question 2

Electroencephalogram (EEG)

Answer 2

Measures general electrical activity in the brain using electrodes (which are fixed to the skull)

The scan records and plots brain wave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity

Unusual, arrhythmic patterns may indicate neurological abnormalities

Question 3

Event-related potentials (ERP)

Answer 3

Detects very small electrical changes in the brain, triggered by a specific event or stimuli

EEG’s record thousands of simultaneous ongoing neural processes, but the brain’s response to a specific stimulus or event is not visible

To establish the specific electrical response (ERP), averaging is used, in which the stimulus is repeatedly presented and a computer displays all of the images of brain activity for each presentation, on top of one another

The ERP is consistent and always present, and other general brain activity is inconsistent and the computer filters it out

Question 4

Post-mortem

Answer 4

Brain is analysed after death to determine whether certain observed behaviours can be linked to structural abnormalities in the brain

Question 5

Strength 1 fMRI

Answer 5

A strength of using fMRI to scan the brain is that is non-invasive with low risks

As the procedure is painless with very few negative side effects

This is because the technique uses no radiation as part of the process, unlike CAT and PET scans

Question 6

FMRI strength 2

Answer 6

FMRI scanning has excellent spatial resolution

Which refers to its ability to accurately localise function

For example, fMRI’s provide very clear and highly accurate images of within 1-2mm when identifying changes in brain activity

Question 7

FMRI limit 1

Answer 7

Poor temporal resolution

Which refers to its ability to precisely measure brain activity as it occurs

This is because there is a five second time lag between brain activity occurring and the image being seen, therefore it can be difficult to establish which areas of the brain are responding to certain tasks

Question 8

FMRI limit 2

Answer 8

FMRI scanning relies fully on patient co-operation

As without this it can be impossible to establish localisation of functioning

This is because a clear and detailed image can only be captured if the patient lays completely still, the slightest movement can significantly impair the quality of the image

Question 9

EEG strength 1

Answer 9

Excellent temporal resolution

Which refers to its ability to precisely measure brain activity as it occurs

For example, unlike fMRI, an EEG can detect brain activity within 1 millisecond of it occurring

Question 10

EEG strength 2

Answer 10

EEG’s have proven invaluable in the diagnosis of conditions such as epilepsy

A disorder that is characterised by random bursts of activity in the brain

For example, EEG’s clearly present the random bursts of activity on screen, so the ability to diagnose such conditions is made easeir

Question 11

EEG limit 1

Answer 11

Poor spatial resolution

Which refers to its ability to accurately localise function

This is because the generalised picture provided by thousands of neurons means the exact source of the activity can be difficult to localise

Moreover, it is difficult to isolate activity from one area from the activity in the adjacent areas, making specific responses to a single stimuli impossible to identify

Question 12

ERP strength 1

Answer 12

Excellent temporal resolution

Which refers to its ability to precisely measure brain activity as it occurs

For example, ERP’s are able to match a stimulus to a response because they occur close together in time

Question 13

ERP strength 2

Answer 13

ERP’s directly measure neural activity, not just blood flow to an area

Which means that researches have been able to identify many different types of ERP and describe their precise role in cognitive functioning

For example, the P100 wave is thought to be involved in the maintenance of working memory

Question 14

ERP limit 1

Answer 14

Poor spatial resolution

Which refers to its ability to accurately localise function

This is because ERP’s don’t exactly identify where the activity is occurring, and often it is difficult to eliminate general brain activity

Question 15

ERP limit 2

Answer 15

Lack of standardisation in ERP methodology

As different research studies use different procedures to identify the ERP

This means that it can be challenging to make valid comparisons, and to conform findings

Question 16

Post-mortem strength

Answer 16

They provided early knowledge and understanding of the effects of brain trauma on functioning

This is because before the use of scanning and technological advances, autopsies from post-mortems were the only way for hypotheses to be generated

For example, findings from post-mortems were vital in providing a foundation for early understanding of key processes in the brain

Question 17

Post-mortem limit

Answer 17

It is difficult to establish a causal relationship between 2 variables

This is because the data collected is used to show that differences in observable behaviour is due to structural abnormalities observed during post-mortem,

When it is possible that other factors could contribute to the development of specific abnormal behaviours