4.2.2 WAYS OF STUDYING THE BRAIN

Question 1

what is an fMRI?

Answer 1

• functional magnetic resonance imaging
• works by detecting blood flow (oxygenated haemoglobin blood which reacts to the magnets) in the brain
• uses large magnets to detect oxygenised blood and show deoxygenated blood
• more active brain areas need more blood flow, this will show as oxygenated blood
• inactive/less active parts will show deoxygenated blood
• active areas can then be compared with areas that are lower in activity and can be shown on the fMRI image

Question 2

what are 4 pros of fMRI?

Answer 2

1) non-evasive and safe technique for patients

2) produces a moving picture, which allows for comparison over time

3) doesn’t require use of radiation

4) produces images with very high spatial resolution of 1mm
-> providing a clear picture of where brain activity occurs

Question 3

what are 4 cons of fMRI?

Answer 3

1) expensive compared to other brain imaging techniques

2) can only capture a clear image if the person being scanned remains very still

3) has poor temporal resolution
-> there’s a 5-second time lag between the image on the screen and actual activity

4) can only measure blood flow
-> can’t show the activity of individual neurones

Question 4

what is spatial resolution?

Answer 4

• refers to the capacity a brain scan has to tell you exactly which area of the brain is active

Question 5

what is temporal resolution?

Answer 5

• describes the scan’s ability to tell you exactly when the activation happened

Question 6

what is an EEG?

Answer 6

• electroencephalogram
• records electrical activity in the brain through electrodes attached to the scalp using a skull cap
• these electrodes measure the activity from the action of millions of neurones, providing an overall account of brain activity
• the output is then amplified + recorded
  -> this device can record spontaneous brain activity / activity in response to a stimulus
• can be used to detect unusual arrhythmic pattens of activity (no particular rhythm)
  -> this can indicate neurological abnormalities like brain disorders or Alzheimer’s disease, brain waves also indicate stage of sleep

Question 7

what are 4 pros of EEG?

Answer 7

1) extremely high temporal resolution
-> can accurately detect brai activity at a resolution of a single millisecond (or less)

2) it’s valuable in diagnosing conditions such as epilepsy, characterised by random bursts of activity which make it easily detectable on screen

3) has contributed much to our understanding in the stages of sleep

4) not as expensive as other techniques

Question 8

what’s a con of EEG?

Answer 8

• low spatial resolution
  -> cannot pinpoint the exact source of neural activity

Question 9

what are ERPs?

Answer 9

• event related potentials (brain activity related to an event)
• is only a general measure of brain activity
• within EEG data are specific sensory, cognitive and motor events
• these can be filled out using ERPs

-> very small voltage changes in the brain that are triggered by specific events or stimuli
-> they establish a specific response to the target stimulus, many presentations of the stimulus and the response it generates are then averaged together
-> any extraneous neural activity from the original EEG recoding is filtered out leaving only those responses that are related to a specific task/stimulus

Question 10

what are 2 pros of ERPs?

Answer 10

1) researchers can identify many different types of ERP and the precise role of these in cognitive function
eg) P300 component is involved in the allocation of attentional resources and working memory

2) they have excellent temporal resolution and are used widely in the measurement of cognitive functions and deficits

Question 11

what are 3 cons of ERPs?

Answer 11

1) they have practical difficulties
-> they’re small and difficult to pick out from other electrical activity in the brain, it’s very time consuming to gather meaningful data

2) it’s not always easy to eliminate background noise and extraneous material

3) critics have pointed out there is a lack of standardisation in ERP methodology between research studies which makes it hard to confirm findings

Question 12

what are post-mortem examinations?

Answer 12

• analysing a person’s brain, often to look for abnormalities that might explain that behaviour + which aren’t doing in control individuals
• areas of damage within the brain are examined after death as a means of establishing the likely cause of a behavioural deficit the person suffered
• this may also involve comparison to a neuro-typical brain in order to measure the extent of the difference

Question 13

what are three cons of post-mortem examinations?

Answer 13

1) causation?
- the deficit a patient displays during their lifetime may not be caused by the deficits found in the brain
- so we can’t conclude that the deficit is caused by the damage found

2) extraneous variables
- there are extraneous factors that can affect the conclusions of post-mortem examinations
eg) medication, age, length of time between death and examination
- ^ are all confounding factors that make the conclusions of research questionable

3) consent?
- there are ethical issues about informed consent prior to death
- many of these examinations are carried out on ppl with severe psychological disorders who would be unable to provide fully informed consent
- yet the examination has still been conducted

Question 14

what are 3 pros of post-mortem examinations?

Answer 14

1) provide hypotheses for future research and improve medical knowledge

2) allow us to see fine details on a neural level (very important for diseases like Alzheimer’s)

3) have provided practical applications such as Broca’s work into speech production difficulties