Brain Scanning Techniques

Question 1

Why do we use brain scanning techniques?

Answer 1

We use scans to examine aspects of the brain and information processing eg thinking, remembering, using language, attending to information, forgetting and problem solving- as well as physiological aspects.
They are used to research brain structure and function and the impact on aggression.
There are 3 types: PET, CAT, fMRI.

Question 2

What are strengths of brain scanning techniques?

Answer 2

• Brain scanning techniques provide an objective way of studying brain structure and function. Don’t require interpretation by researchers so avoids bias and subjective interpretation.
• Brain scans can easily be replicated as they used a standardised procedure so the research can check for the consistency of results increasing the reliability of findings about human behaviour.
• Raine et Al found differences in murderer brain activity using PET scans showinf their contribution to understanding the brain and human behaviour. Helps make them very applicable to human research.

Question 3

What are weaknesses of brain scanning techniques?

Answer 3

• Brain scanning lacks ecological validity as it takes place in an artificial setting. This means that data collected cannot be applied to everyday life as there may be different activity in the brain when an activity is completed in a real life setting.
• Frequent exposure to radiation could mean brain scanning could by unethical. Studying a person’s brain for psychological research while causing physical harm goes against the BPS ethical guidelines.
• Brain scanning techniques have a high level of cost, so are not always a practical way of analysing the brain.
• Brain scanning techniques are not suitable for certain individuals such as those with claustrophobia or pregnant women, as the individual would not be able to cope with prolonged periods of time in enclosed scanners or it could cause damage to the unborn baby.

Question 4

Describe what a CAT scan is (computerised axial tomography).

Answer 4

CAT scans use multiple X-days to produce a cross-sectional image of brain regions. A CAT scan produces pictures in slices which can be looked at individually or can be put together to give a 3-dimensional view of the whole area, such as part of the brain. The pictures are formed and pick up how the area beinf scanned reacts to the x-eat being passed through it, showing how far the x-rat is blocked. Knowing how areas block the x-rat shows something about the area, such as whether a tumour is present. In psychology CAT scans can be used to understand damage to the brain.

Question 5

What happens in a CAT scan?

Answer 5

In a CAT scan a person lies on a moving platform to be passed through the scanner or for the person to lie still and the scanner moves around them. It can take a few minutes to 30 minutes.

Question 6

What are strengths of CAT scans?

Answer 6

• Non-invasive as there is no injection involved. Safe to use as no radioactive materials used. Allows it to be used over time as no harm from repeating scans so can track changed over time eg to see if a treatment had improved a condition.
• CAT scans can easily be replicated as they used a standardised procedure so the research can check for consistency of results increasing the reliability of findings about human behaviour.

Question 7

What are weaknesses of CAT scans?

Answer 7

• Require more radiation than traditional x-rays and the more detailed and complex the CAT scan is, the more radiation exposure the patient receives. This risks putting the participant at physical harm so is unethical as this is against the BPS ethical guidelines for psychological research.
• CAT scans only provide structural information about the brain, they don’t tell us about function. This means they have limited validity in studying brain areas and they role in particular behaviours.

Question 8

Describe what a PET scan is (positron emission tomography).

Answer 8

A PET scan is used to measure ththe activity of the brain, it highlights “hot spot” areas in the brain which tells us which parts of the brain are working at certain times.

Question 9

Describe what a PET scan is (positron emission tomography).

Answer 9

A PET scan is used to measure the activity of the brain, it highlights “hot spot” areas in the brain which tells us which party’s of the brain are working at certain times. PET scans investigate brain activity when a human is doing a task. PET involved injecting a radioactive tracer into the participant.
A computer generated images from the information from the information and a radioactive tracer is added to oxygen or glucose- something that the body uses. As the tracer is used on the brain, this will show up as an area of activity. The tracer reaches the brain about 1 minute after being injected and takes 10-15 minutes to decay. As the tracer decays, it releases minute amounts of radioactivity (initially in forms of positions). The emission of radioactive particles is detected by the scanner and used to produce a record of the levels of activity in the brain tissue. This shows up as an image which can then be interpreted.

Question 10

How do you conduct a brain scan (PET)?

Answer 10

• The PPS would be given a radioactive tracer before they toon part so the PET scan can measure their brain activity in response to the stimuli.
• The researcher would need to take a measure of the testing brain activity prior to any stimuli being presented to the participants.
• The researcher would then show each participant the stimuli to measure the brain activity in response to the stimuli.

Question 11

What are strengths of PET scans?

Answer 11

• A PET scan will give a researcher an image of the PPS brain activity when they see the stimuli that can be checked by other researchers which increases the reliability of her findings as multiple researchers can interpret the scan to achieve consistency of the results.
• PET scans are a valid measurement of brain activity as they provide a detailed image of brain activity during the completion of a task showing function not just structure of the brain.

Question 12

What are weaknesses of PET scans?

Answer 12

• PET scans involve injecting a radioactive glucose tracer into PPS which could be dangerous therefore limiting the number of times that it can be used with the same PPS.
• Scanners restrict movement so brain activity can only be studied in passive bodily states eg listening or imagining, real action and moving around is limited so PET scans lack ecological validity as they are not measuring brain function in real-life settings.

Question 13

Describe what an fMRI scan is (functional magnetic resonance imaging).

Answer 13

The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast. This is a type of specialised brain and body can used to map neural activity in the brain or spinal cord of humans or other animals by imaging the change im blood flow (hemodynamic response) related to energy use by brain cells. Since the early 1990s, fMRI has come to dominate brain mapping research because it does not require people to undergo surgery, to ingest substances, or be exposed to radiation.
- fMRI refers to functional MRI scanning, which is the same as an MRI scan but looks at the “function” of the brain. Blood and oxygen levels are measured and the scan picks up on changes of use of brain areas depending on the task being carried out. Changes in flood flow highlight neural activity, the FMRI looks at the blood flow showing brain cell use of energy. So the fMRI looks at brain functioning using changes in blood flow when different areas of the brain are used.
fMRI is now used instead of PET scanning as it highlights differences in brain flow to a high degree of accuracy and with sensitivity, is useful for those at risk of, or who have had, strokes. So there is medical application as well as application to understanding the brain.
Areas in psychology thay fMRI scanning has contributed to include looking at regions of the brain at work when we use language and seeing if both sides of the brain are equally used, checking memory regions, looking for onset of Alzheimer’s and looking at mental health issues like depression to see effects on brain functioning.

Question 14

How do you conduct an fMRI scan?

Answer 14

• PPS asked to lie in scanner to take measure of testing brain activity prior to any stimuli presented.
• Researchers then show different stimuli to measure brain activity in response.

Question 15

What are strengths of an fMRI scan?

Answer 15

• Non-invasive as there is no injection involved. Safe to use as no radioactive materials used. Allows it to be used over time as no harm from having repeated scans so can track changes over time eg to see if a treatment has improved a condition.
• High spatial resolution- a high resolution fMRI machine can identify the brain region up to an accuracy of 1mm. This allows for good accuracy of the region being activated by the task. Increases validity.
• Indicates function , not just structure, so tells us which parts of the brain are active in different tasks. More useful in understanding human behaviour.

Question 16

What are weaknesses of an fMRI scan?

Answer 16

-fMRI scanning takes place in an artificial setting which lowers ecological validity. This means that PPS may not show natural behaviour due to the situation being different to everyday life.
- fMRI scanning is not practical for those with pace makers as the magnetic field can cause physical disruption to the hearty as they use a high powered electromagnet.
- Not suitable for those with claustrophobia, as the scan takes place in a confined space and there is a lot of loud noise made by the scanner.