Ways of Studying the Brain

Question 1

Functional Magnetic Resonance Imaging (fMRI):

Answer 1

Measures brain activity while a person is performing a task that uses MRI technology. Detects which regions of the brain are rich in oxygen and are active.

Question 2

Electroencephalogram (EEG):

Answer 2

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

Question 3

Event-related potentials (ERPs):

Answer 3

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

Question 4

Post-mortem examination:

Answer 4

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

Question 5

How does fMRI work?

Answer 5

1. Detects the changes in blood oxygenation and flow that occurs as a result of brain activity in specific parts of the brain.
2. When a brain area is more active it consumes more oxygen and to meet this increased demand, blood flow is directed to the active area (haemodynamic response).
3. fMRI produces 3-D images (activation maps) showing which parts of the brain are involved in a particular mental process.
4. Important implications for our understanding of localisation of function.

Question 6

Pros and Cons of fMRI:

Answer 6

1. Unlike, PET, it does not use radiation. If administered correctly it is virtually risk-free, non-invasive and straight forward to use.
2. Produces images that have very high resolution depicting detail by the milimetre.
3. Very expensive and can only capture a clear image if the person stays perfectly still.
4. Has poor temporal resolution because there is around a 5-second time lag behind the image on screen and the initial firing of neuronal activity.
5. fMRI can only measure blood flow in the brain, cannot hone 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 screen.

Question 7

How does EEG work?

Answer 7

1. Measures electrical activity within the brain via electrodes that are fixed to individual’s scalp using a skull cap.
2. The scan recording represents the brainwave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity.
3. EEG is often used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity.
4. May indicate neurological abnormalities such as epilepsy, tumours or disorders of sleep.

Question 8

Pros of EEGs:

Answer 8

1. Proved invaluable in the diagnosis of conditions such as epilepsy, a disorder that can be random bursts of activity in the brain that can easily be detected on screen.
2. Contributed much to our understanding of the stages involved in sleep.
3. Unlike fMRI, it has high temporal resolution and can detect brain activity at a resolution of a single millisecond.

Question 9

Cons of EEG:

Answer 9

1. Generalised nature of the information received (that of many thousands of neurons).
2. The EEG signal is not useful for pinpointing the exact source of neural activity and does not allow researchers to distinguish between activities originating in different but adjacent locations.

Question 10

How do ERPs work?

Answer 10

1. In its raw form it is a crude and overly general measure of brain activity.
2. Within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists.
3. Using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to a specific stimulus.
4. What remains are ERPs: types of brainwave that are triggered by particular events.

Question 11

Pros of ERPs:

Answer 11

1. Bring more specificity to the measurement of neural processes that could ever be achieved using raw EEG data.
2. As ERPs are derived from EEG measurements, they have excellent temporal resolution, when compared to fMRI.
3. Led to their widespread use in the measurement of cognitive functions and deficits.
4. Researchers have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning for instance, the P300 component is thought to be involved in the allocation of attentional resources.

Question 12

Cons of ERPs:

Answer 12

1. Lack of standardisaion in ERP methodology between different research studies which it difficult to confirm findings.
2. To achieve pure data in ERP studies, background noise and extraneous material must be completely eliminated and this may not be completely eliminated, not always be easy to achieve.

Question 13

How do post mortem examinations work?

Answer 13

1. Analysis of a person’s brain following their death.
2. Individuals who are subject to a post-mortem are likely to have had a rare disorder.
3. Areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person experienced.
4. May involve comparison with a neurotypical brain in order to ascertain the extent of the difference.

Question 14

Pros of post-mortem:

Answer 14

1. Vital in providing a foundation for early understanding key processes in the brain.
2. Broca and Wernicke relied on post-mortem studies in establishing links between language, brain and behaviour decades before neuroimaging was possible.
3. Improved medical knowledge and help generate hypotheses for further study.

Question 15

Weaknesses of post-mortem:

Answer 15

1. Causation is an issue within these investigations, damage may not be linked to the deficits under review but to some other unrelated trauma of decay.
2. May raise ethical issues of consent from individuals before death.
3. May not be able to provide informed consent, in the case of HM who lost his ability to form memories and was not able to provide such consent.