Ways of studying the brain

Question 1

Name the different brain scanning techniques

Answer 1

• Functional magnetic resonance (fMRI)
• Electroencephalogram (EEGs)
• Event related potentials (ERPs)
• Post mortem examinations

Question 2

Define fMRI

Answer 2

A method used to measure brain activity while a person is performing a task. fMRI detects radio waves from changing magnetic fields. This enables researchers to detect which regions of the brain are rich in oxygen and thus are active.

Question 3

fmri

Answer 3

Question 4

How does an fMRI work?

Answer 4

fMRI works by detecting the changes in blood oxygenation and flow that occurs as a result of neural (brain) activity in specific parts of the brain. An active brain area consumes more oxygen.

Question 5

What does an fMRI produce?

Answer 5

fMRI produces 3D images that are activation maps, showing which parts of the brain are using larger amounts of oxygen and are therefore more active.

Question 6

Give some strengths of fMRI

Answer 6

• fMRIs, unlike PET scans, do not rely on the use of radiation.
• fMRIs are virtually risk-free, non-invasive and straightforward to use.
• It produces images that have a very high spatial resolution, giving detail by the millimetre. This means fMRI can safely provide a clear picture of brain activity.

Question 7

Give some limitations of fMRI

Answer 7

• fMRI is expensive compared to other neuroimaging techniques and can only capture a clear image if the person stays perfectly still.
• It has poor temporal resolution because there is around a 5 second time-lag behind the image on the screen and the firing of the neurons.
• fMRI can only measure blood flow in the brain. It cannot home in on the activity of individual neurons and so it can be difficult to tell exactly what kind of brain activity is being represented on the screen.
  THIS MEANS fMRI MAY NOT TRULY REPRESENT MOMENT-TO-MOMENT BRAIN ACTIVITY.

Question 8

Define electroencephalogram (EEG)

Answer 8

A record of the tiny electrical impulses produced by the brain’s activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain.

Question 9

EEG

Answer 9

Question 10

How do EEGs work?

Answer 10

EEGs measure electrical activity within the brain via electrodes that are fixed on the scalp, usually using a skull cap.

Question 11

What do EEGs produce?

Answer 11

The scan recording represents the brainwave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity.

Question 12

Who are EEGs often used by and why?

Answer 12

EEGs are often used by clinicians as a diagnostic tool. This is because unusual arrhythmic patterns of activity (no particular rhythm) may indicate neurological abnormalities such as epilepsy, tumours, or disorders of sleep.

Question 13

Give some strengths of EEGs

Answer 13

• EEGs are important in the diagnosis of conditions such as epilepsy, a disorder characterised by random burst of activity in the brain that can be easily detected.
• Similarly, it has contributed much to our understanding of the stages involved in sleep (more on this later).
• Unlike fMRI, EEG technology has extremely high temporal resolution.
• Today’s EEG technology can accurately detect brain activity at a resolution of one millisecond.

Question 14

Give some limitations of EEGs

Answer 14

• EEGs tend to produce very generalised information so it is not useful for pinpointing the exact source of neural activity.
• EEGs do not allow researchers to distinguish between activity originating in different but adjacent locations of the brain.

Question 15

Define event-related potentials (ERPs)

Answer 15

The electrophysiological response of the brain to a specific sensory, cognitive or motor event that can be isolated through statistical analysis of EEG data.

Question 16

erp

Answer 16

Question 17

What do ERPs use?

Answer 17

EEG data but use statistical averaging techniques to isolate specific neural responses associated with sensory, cognitive and motor events.

Question 18

Who are ERPs of interest to?

Answer 18

Cognitive neuroscientists

Question 19

How do ERPs work?

Answer 19

• ERPs work by using statistical averaging techniques, that filters out extraneous brain activity from the original EEG recording, leaving only the responses that relate to say, the presentation of a specific stimulus or performance of a specific task.
• Event-related potentials remain; types of brainwaves that are triggered by particular events.

Question 20

What has research shown about ERPs?

Answer 20

Research has shown different forms of ERPs, linked to cognitive processes such as attention and perception.

Question 21

Give some strengths of ERPs

Answer 21

• ERPs partly address the limitations of EEG.
• ERPs bring much more specificity to the measurement of neural processes than could be achieved using raw EEG data.
• As ERPs are derived from EEG measurements, they have excellent temporal resolution, especially when compared to fMRIs.
• The excellent temporal resolution of ERPs have led to their widespread use in the measurement of cognitive functions and deficits.
• Researchers have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning including parts of working memory.

Question 22

Give some limitations of ERPs

Answer 22

• Critics have pointed to a lack of standardisation in ERP methodology between different research studies, making it difficult to confirm findings.
• A further issue is that, in order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, which is not always easy to do.

Question 23

Define post-mortem examinations

Answer 23

The brain is analysed after death to determine whether certain observed behaviours during the person’s lifetime can be linked to structural abnormalities in the brain.

Question 24

post mortem

Answer 24

Question 25

How do postmortem examinations work?

Answer 25

• This is a technique that involves the analysis of a person’s brain following their death.
• Areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person suffered.
• This may also involve comparison with a neurotypical (healthy) brain in order to see the extent of the difference.

Question 26

What does psychological research show about postmortem examinations?

Answer 26

In psychological research, those whose brains are subject to a post-mortem are likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime.

Question 27

Give some strengths of post-mortems

Answer 27

• Post-mortem (PM) evidence was vital in providing a foundation for early understanding of key processes in the brain.
• Both Broca and Wernicke relied on PM studies in establishing links between language, brain, and behaviour decades before neuroimaging began.
• PM studies improve medical knowledge and help generate hypotheses for further study.

Question 28

Give some limitations of post-mortems

Answer 28

• Causation is an issue within these investigations.
• Observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay.
• PM studies raise ethical issues of consent from the patient before death.
• Patients may not be able to provide informed consent, for example in the case of HM who lost his ability to form memories and was not able to provide such consent. Nevertheless PM research has been carried out on his brain.