Using Scanning to Study the Brain

Question 1

Why do we use brain scans?

Answer 1

Helps understand the relationship between different parts of the brain and their functions; helps locate affected areas in the brain by neurological disorders and devise new strategies of scanning for treatment

Question 2

How is the procedure similar for all types of scans?

Answer 2

The individual lies down in the scanner, as still as possible, whilst detectors circle their heads, obtaining information about one ‘thin slice’ of brain at a time

Question 3

How is ‘thin slices’ produced by brain scans useful?

Answer 3

Using multiple “slices”, we can build up a 3D image of the brain

Question 4

define spatial resolution

Answer 4

how much fine detail is presented in the scan image

Question 5

Why is spatial resolution good?

Answer 5

high spatial resolution shows more detailed images

Question 6

define temporal resolution

Answer 6

how well the scanner tracks the changes in brain activity over time

Question 7

why is temporal resolution good?

Answer 7

higher temporal resolution scanners are more responsive to short-term changes in the brain

Question 8

Define voxel size

Answer 8

a 3D pixel, on the image of a scan

Question 9

What is C.A.T stand for?

Answer 9

Computerised Axial Tomography

Question 10

How are CAT scans similar to X-rays?

Answer 10

It involves passing x-rays though a person’s brain where the beams are then interpreted by a computer however, unlike an X-ray, it uses multiple angles of the brain

Question 11

Why are CAT scans considered useful?

Answer 11

they are useful for detecting damage or tumours as well as allowing a detailed picture of the brain to be seen

Question 12

What do CAT images show?

Answer 12

a grey-scale image, of high detail about the structure of the brain: images of bone, soft tissue and blood vessels imaged simultaneously

Question 13

How are CAT scans inferior to PET/fMRI scans?

Answer 13

they do not convey information about brain activity or function which limits their psychological usefulness

Question 14

how are CAT scan useful in terms of psychologically understanding?

Answer 14

Their level of detail in brain structures is useful when relating brain damage to psychological functioning

Question 15

What are CAT scan’s resolutions?

Answer 15

Spatial resolution of 0.5mm (voxel size) and no temporal resolution as it only creates images of brain structure

Question 16

How much does a CAT scan cost?

Answer 16

Around £1 million and takes round 5 minutes per scan, which roughly translates to £100-£400 per scan

Question 17

What are the strengths of CAT scans?

Answer 17

Easier to plan surgeries as structures are seen before beginning the operation

Non-invasive, though sometimes a dye is injected for higher clarity

Removes the need for exploratory surgery

Reduces the time an individual must spend under general anaesthetic

Cheaper and somewhat faster than PET/fMRI scans

Question 18

What are the weaknesses of CAT scans?

Answer 18

• Involves radiation, and therefore unadvised for pregnant women as radiation may harm the unborn child
• Risk of overexposure to radiation,

Question 19

What does f.M.R.I stand for?

Answer 19

Functional Magnetic Resonance Imaging

Question 20

How does an fMRI scan work?

Answer 20

It scans the blood flow in the brain. The individual’s head is placed within a large electromagnet, and they are given a task to do. As neural activity increases, so does blood flow: active areas require more blood and the scan shows where the blood goes. The haemoglobin within the blood dispels the magnetic field when oxygenated and goes with the magnetic field when deoxygenated - these differences help the scanner to create an image.

Question 21

Why is fMRI scans favoured by scientists more so than PET scans?

Answer 21

It has a higher spatial resolution, non-invasive and lacks radiation exposure to the participant

Question 22

Why is fMRI scan practically useful?

Answer 22

No need for radioactive tracers, although small movements may badly affect fMRI scans and so cannot be used to may different types of chemicals within the brain like PET scans`

Question 23

How are fMRI scans similar to PET scans?

Answer 23

They both generate images of active brain areas, and so have the same applications and strengths

Question 24

What is the resolution of fMRI scans?

Answer 24

1.5mm (voxel size) spatial resolution and a temporal resolution of 20 seconds

Question 25

How much does a fMRI scan cost?

Answer 25

A scanner cost around £1.9 million, and takes around 30-40 seconds which roughly translates to around £200- £500 per scan

Question 26

What are the strengths of fMRI scans?

Answer 26

• High temporal resolution (with 4 images per second)
• Can be done during tasks, allowing scientists to infer about brain localisation and function

-Non invasive

Question 27

What are the weaknesses of fMRI scans?

Answer 27

• Can trigger claustrophobia for some patients as they would have to lie still in a large tube for the duration of the scan
• Unsuitable for some magnets or people with pacemakers/recent metallic surgical implants

Question 28

What does P.E.T scan stand for?

Answer 28

Positron Emission Tomography

Question 29

How do PET scans work?

Answer 29

A patient is injected with radioactive substances (FDG) which conducts the scan. Once the radioactive tracer is absorbed into the bloodstream (which takes around 30 mins), a task is given to stimulate the blood supply within the brain and encourage activity. The tracer attaches itself onto glucose molecules (which are used as energy by the brain). Once the glucose is used up, the tracers produce gamma rays which are picked up by the scammer: a high activity within a brain region means a higher concentration of gamma rays within that region (warm colours).

Question 30

How are PET scans useful to scientists and psychologists?

Answer 30

Its ability to investigate brain activity makes it useful, as brain activity can be compared to different tasks to strengthen localisation of the brain - it can investigate a wider range of brain functions and behaviours, through mapping different types of chemicals within the brain

Question 31

What are the limitations of PET scans in relation to fMRI and CAT scans?

Answer 31

Brain structure portrayal is less detailed

Question 32

What are the resolution within PET scans?

Answer 32

Spatial resolution of 6mm (voxel size) and a temporal resolution of 5-15 mins

Question 33

How much does a PET scan cost?

Answer 33

A scanner costs around £2 -3 million, with higher running costs due to the need to have a facility to make the short-lived radioactive isotopes used as radioactive tracers and hence this roughly translates to £500-£800

Question 34

What are the strengths of PET scans?

Answer 34

• Helps doctors see existing problems and predict future problems
• Good for monitoring of progressive neurodegenerative diseases

Question 35

What are the negatives of PET scans?

Answer 35

• Cannot have too many scans as this will negatively affect the patient’s health
• More invasive than CAT scans, and some may object to the insertion of radioactive tracers (although it does decay quickly)

-Expensive and hence only used for diagnostic purposes

Question 36

Why is Raine et al. (1997) important when using scanning to understand the brain?

Answer 36

Raine et al. (1997) used PET scans to compare murderers with ordinary people. They found that the murderers had different patterns of brain activity in the forebrain and the limbic system.

Question 37

Why is Hirvonen et al. (2011) important when using scanning to understand the brain?

Answer 37

Hirvonen et al. (2011) used PET scans to show that long-term users of cannabinoid drugs show changes to the brain.

Question 38

Why is Gazer et al. (2000) important when using scanning to understand the brain?

Answer 38

Gazer et al. (2000) used MRI scans to show that schizophrenia patients had reduced volumes of brain tissue compared to a comparison group.

Question 39

Why is Carlsson et al. (2000) important when using scanning to understand the brain?

Answer 39

Carlsson et al. (2000) used a range of studies, including brain imaging to show that schizophrenia is related to abnormalities in brain systems that use dopamine and glutamate as their main neurotransmitter.

Question 40

Define brain scanning/imaging

Answer 40

using technology to produce images of brain structure and/or activity without needing to open up the skull.

Question 41

Define CAT scan

Answer 41

an imaging technology that uses X-rays to generate pictures of brain structure.

Question 42

Define PET scan

Answer 42

an imaging technology that generates images of brain activity by tracing the uptake of glucose in different brain areas.

Question 43

Define fMRI scan

Answer 43

an imaging technology that generates images of brain structure and activity by tracking the movement of water/blood in different brain areas.

Question 44

What research methods are used when trying to understand how brain scanning is used to understand the brain?

Answer 44

Brain-scanning techniques (CAT, PET and fMRI)