BP- Studying the brain

Question 1

What are post-mortem examinations?

Answer 1

• Psychologists may study a person who displays an interesting behaviour while they are still alive.
• When the person dies, the psychologists look for abnormalities in the brain that might explain their behaviour.

Question 2

Give advantages of post mortem examinations.

Answer 2

1) Allow for detailed examinations and measurement of deep brain structures (e.g. the hypothalamus) not measurable by brain scans.
2) Highly applicable – Broca and Wernicke both relied on post mortem studies in establishing links between language, brain and behavior decades before neuroimaging ever became a possibility – Evidence has improved medical knowledge and less money can be used by the NHS on less efficient techniques which generates a positive impact on the economy.

Question 3

Give limitations of post mortem examinations.

Answer 3

• The issue of causation – The deficit a patient displays during their lifetime may not be linked to the deficits found in the brain, they may be the result of another illness – Psychologists are unable to conclude that the deficit is caused by the damage found in the brain. Various factors can act as confounding variables and might confuse findings/conclusions. For example, length of time between death and post-mortem, other damage caused to the brain either during death or as a result of disease, age at death, drugs given in months prior to death, etc.
• Ethical issues – Deceased people are not able to provide informed consent such as HM because of his lack of short term abilities – There will be problems with replicability because future ethical guidelines will be stricter.

Question 4

What are event-related potentials? (ERP)

Answer 4

ERP’s are very small voltage changes in the brain triggered by specific events or stimuli which are measured using an EEG.

Question 5

What do event related potentials measure?

Answer 5

Measures small voltages of electrical activity when a stimulus is presented. Because these small voltages are difficult to pick out from other electrical signals in the brain, the stimulus needs to be repeatedly presented, and only signals which occur every time the stimulus is presented will be considered an ERP for that stimulus.

Question 6

What are the two types of event-related potentials?

Answer 6

1) Sensory ERPs

2) Cognitive ERPs

Question 7

What are sensory ERPs?

Answer 7

Sensory ERPs are those that occur within 100 milliseconds of stimulus presentation

Question 8

What are cognitive ERPs?

Answer 8

those that occur 100 milliseconds or more after stimulus presentation.

Question 9

what do sensory ERPs indicate?

Answer 9

Sensory ERPS indicate the brain’s 1st recognition of a stimulus.

Question 10

what do cognitive ERPs indicate?

Answer 10

Cognitive ERPS represent information processing and evaluation of the stimulus.

Question 11

What are the strengths of event-related potentials?

Answer 11

1) ERPS provide a continuous measure of neural activity in response to a stimulus. Therefore, changes to the stimulus can be directly recorded: e.g. if a blue coloured slide turned green.
2) Derived from EEG – Excellent temporal resolution compared to fMRI – Much more specificity has led to their widespread use in the measurement of cognitive functions and deficits.
3) Non-invasive - No insertion of instruments unlike PET and no exposure to radiation – Virtually risk free and is avoidant of any danger to the brain itself.

Question 12

What are the limitations of event related potentials?

Answer 12

1) ERPS only monitor electrical activity in outer layers of the brain, therefore, cannot reveal electrical activity in deeper brain sites.
2) Extraneous stimuli must be eliminated in order to collect pure data, the participant may react to background noise or a difference in temperature – For experiments where these variables can’t be controlled, it’s difficult to draw conclusions.
3) Lack of standardisation in methodology between studies – Different groups will use varying averages on what neural activity they decide to filter out – Hard to replicate experiments and confirm findings in a peer review study.

Question 13

What do electroenphalograms measure? (EEGs)

Answer 13

Measures electrical activity in the brain using electrodes attached to the scalp, and measures how electrical activity in the brain varies over time/in different states (e.g. waking vs. asleep).

Question 14

What are the 4 basic wave patterns?

Answer 14

1) Alpha
2) Beta
3) Delta
4) Theta

Question 15

What state is alpha in?

Answer 15

Awake and relaxed

Question 16

What state is beta in?

Answer 16

Awake and highly aroused or in REM (rapid eye movement sleep)

Question 17

What is delta?

Answer 17

Deep sleep

Question 18

What is theta?

Answer 18

Light sleep

Question 19

Give strengths of EEGs.

Answer 19

1) Records brain activity over time and can, therefore, monitor changes as a person switches from task to task or one state to another (e.g. falling asleep).
2) EEGs have medical applications in diagnosing disorders such as epilepsy and Alzheimer’s.
3) Non-invasive - No insertion of instruments unlike PET and no exposure to radiation – EEGs are virtually risk free and is avoidant of any danger to the brain itself.
4) Cheaper than fMRI thus making them more available – Psychologists can gather more data on the functioning of the human brain thus contributing to our understanding of different psychological phenomena.

Question 20

Give limitations of EEGs.

Answer 20

1) EEGs only monitor electrical activity in outer layers of the brain, therefore, cannot reveal electrical activity in deeper brain sites.
2) Not highly accurate – electrical activity detected in several regions of the brains simultaneously – Very hard to pinpoint exactly which area is producing this activity. therefore cannot distinguish differences in activity between 2 closely adjacent areas.
3) Uncomfortable – Hard for the patients as electrodes are attached to their head – Could result in an unrepresentative reading as the patients discomfort could trigger cognitive responses to the real time situation.

Question 21

What is functional magnetic resonance imaging? (fMRI)

Answer 21

• A brain scanner which measures increased blood flow to brain sites when individuals are asked to perform cognitive/physical tasks.
• Increased blood flow indicates increased demand for oxygen in that area.
• This produces 3D images showing which parts of the brain are involved in a particular mental process, important for our understanding of localisation of function.

Question 22

Give a strength of fMRI.

Answer 22

Non-invasive – No insertion of instruments unlike PET and no exposure to radiation – Beneficial to the economy as there is no recovery time so people don’t have to be off work.

Question 23

Give limitations of fMRI.

Answer 23

1) fMRI only measures blood flow – it cannot home in on the activity of individual neurons therefore it’s hard to tell exactly what brain activity is being represented on the screen – High likelihood that the findings will be misinterpreted as it doesn’t show activity like EEG/ERP. •
2) fMRI may overlook the interconnectivity of brain sites. By only focusing on brain sites receiving increased blood flow, it fails to account for the importance of brain sites connecting/communicating with each other.
3) Expensive – Other neuroimaging techniques such as EEG may be cheaper and it can only capture a clear image if the person stays still – May not be worthwhile for the NHS to fund it.