Methodologies -brain Scans

Question 1

Brain scan description

Answer 1

A technique used to investigate the functions of the brain by taking either 2D or 3D images of the living brain.

Question 2

Computerised Axial Tomography (cat or ct) scan

Answer 2

Computerised Axial Tomography (CAT or CT): involves a series of x-rays and when combined they can create two or three-dimensional pictures - Torrey (2002) - found on average 15% larger ventricle sizes (cavities or gaps in the brain) with schizophrenics than a control group, suggesting brain deterioration is a cause.

Question 3

Magnetic resonance imaging (mri ) and functional magnetic imaging (fmri) scan

Answer 3

Magnetic Resonance imaging (MRI) and Functional Magnetic Imaging (FMRI): uses a magnetic field to change hydrogen atom alignment in the brain. The electromagnetic signal is measured to produce detailed two and three dimensional images - Maguire et al (2000) found London taxi drivers had larger hippocampus than control, suggesting the hippocampus is responsible for memory of routes.

Question 4

Positive emission tomography (pet) scan

Answer 4

Positron Emission Tomography (PET): administer a slightly radioactive glucose (sugar) tracers - injection.
The most active parts of the brain use the glucose tracers, radiation detectors ‘see’ the radioactive glucose tracers. Can produce still and moving images of brain activity. Raine et al (1997) measured differences in glucose metabolism in areas of the brain between murders and a control.

Question 5

Cat scan advantages and disadvantages

Answer 5

• good for identifying structural abnormalities in the brain such as tissue damage
  -better quality than traditional X-rays

-less detail shown and can’t show the brain in action unlike pet scans
-expose participants to more radiation and can’t be used on pregnant women

Question 6

MRI scan advantages and disadvantages

Answer 6

-provides a more detailed image of soft tissues than cat and pet scans

• take a long time and can be uncomfortable
• can’t show the brain in action like pet scans

Question 7

Pet scan advantages and disadvantages

Answer 7

-can show the brain in action
-use while conducting tasks as patients are alive and awake

-less precise than mri scans
- more costly thus less accessible than cat and mri scans

Question 8

Overall advantages of using brain scans

Answer 8

+Provides a detailed and objective measure of neural activity which has little opportunity
often inaccessible to researchers.
+ Unlike post mortem studies you can investigate neural activity in action (e.g.
Raine’s study using a continuous performance task with live participants.
+ PET scans reveal chemical information that is not available with other imaging techniques

Question 9

Overall weakness of using brain scans

Answer 9

-scanning machines are expensive and therefore often inaccessible to researchers
-some scans such as pet scans can take a long time and can be uncomfortable for participants.this may reduce the number of people who would wish to take part and would be in appropriate for those who suffer from claustrophobia
- only a range of activities can be investigated due to limitations of being stuck in a machine