brain scans

Question 1

CAT scan AO1

Answer 1

• multiple beams of x-rays are passed around the head from different angles
• a computer produces a DETAILED image of the STRUCTURE of the brain
• useful for finding tumours and areas of brain damage

Question 2

strength of CAT scans

Answer 2

High spatial resolution as CAT scans have a low voxel size of 0.5mm. Therefore, they produce the most fine detail of the structure of the brain, so you can detect tumours and areas of brain damage.

Question 3

weaknesses of CAT scans

Answer 3

Due to having a high spatial resolution as they have a small voxel size of 0.5mm, CAT scans are very susceptible to motion related artefacts and are sensitive to movement. Therefore, any head movements can cause the scanner image to blue, leading to inaccurate estimates of size and location of brain areas.

Question 4

PET scan AO1

Answer 4

• patient is injected with radioactive tracer substance (FDG injection)
• the radioactive atom is attached glucose
• the brain uses up glucose as a form of energy
• once the tracer is absorbed into the bloodstream, the patient can be given a task to stimulate the brain
• as glucose is used up, the radioactive atoms breakdown and emit positrons
• more gamma rays will be produced in areas of high activity
• areas of high activity will show warmer colours like red, areas of low activity will show cooler colours like blue
• can be used to detect tumours and damage

Question 5

strength of PET scans

Answer 5

Lower spatial resolution as their voxel size is 6mm, so they are not as susceptible to motion related artefacts and are not sensitive to movements. Therefore, any small head movements will not cause the scanner image to blur leading to an inaccurate representation of brain functioning.

Question 6

weakness of PET scans

Answer 6

Unethical due to the use of the radioactive tracer substance (FDG injection, which has a radioactive atom attached to glucose). Therefore, making the scan invasive and could lead to physical harm.

Question 7

fMRI scans AO1

Answer 7

• brain activity is associated with blood flow
• head is placed in a large and powerful electromagnet - areas of high activity have increased blood flow to provide oxygen
• oxyhaemoglobin repels a magnetic field (dimagnetic)
• hb follows the direction of the magnetic field (paramagnetic)

Question 8

strength of fMRI scans

Answer 8

High temporal resolution of about 20 seconds, so it generates the fastest image of brain activity. Therefore, it is quick and easy to use to track changes in brain activity.

Question 9

weakness of fMRI

Answer 9

High spatial resolution as the voxel size is 1.5mm, so fMRI scans are susceptible to motion related artefacts and are sensitive to movement. Therefore, head movements could lead to the scanner image blurring and producing an inaccurate representation of brain functioning.