brain scans

Question 1

PET

Answer 1

PET scans investigate brain activity when a human is doing a task
* PET involves injecting a radioactive tracer into the participant
* This irradiates the glucose supply in the brain
* When an area is active (and therefore using lots of glucose) it gives off more gamma rays which are detected
* Areas of high energy will be red/orange (warm colours)
* Areas of low energy will be blue/green (cold colours)

Question 2

fMRI

Answer 2

• fMRI looks records brain activity and produces an anatomical picture of the brain
• fMRI uses magnetic and radio waves.
• The person lies in a large cylinder (which can be claustrophobic) in which they must lie perfectly still
• Magnet and radio waves are then sent through the body
• As neural activity increases in the brain, blood flow increases in active areas and requires more oxygen.
• Oxygen is carried to the areas via haemoglobin in red blood cells
• Haemoglobin when it is full of oxygen repels the magnetic field (diamagnetic) but follows the field when it is deoxygenated (paramagnetic) and it uses these changes to build up an image.

Question 3

CAT

Answer 3

• CAT scans use multiple X-rays to produce a crosssectional image of brain regions
• This is done at many angles (an X-Ray is only a 2D image and gets ‘confused’ with objects behind one another) which can then be put together into a full picture
• This lets us see the structure of the brain such as if there is damage/tumours