CAT, PET, fMRI

Question 1

What does a CAT scan show?

Answer 1

Shows structure not function

Question 2

Why is a CAT scan useful?

Answer 2

Useful for detecting areas of brain damage following an accident or positioning of trumours

Question 3

How does a CAT scan work?

Answer 3

X ray beams passed through the head from different angles to create cross sectional images of the brain showing structure

Question 4

Is a CAT scan invasive?

Answer 4

No

Question 5

What does a PET scan show?

Answer 5

Activity, most and least active areas. Warm colours = more activity. Cool colours = less activity

Question 6

What is injected into the bloodstream for a PET scan to work?

Answer 6

A radioactive tracer that is used up during brain activity, reaches the brain after 1 minute

Question 7

What is radioactivity in the form of in PET scans?

Answer 7

Gammar rays

Question 8

How does a PET scan work?

Answer 8

Brain cells take up oxygen in the water/glucose, tracer decays, releases radioactivity - positrons, active areas have more radioactivity

Question 9

Why is a PET scan reliable?

Answer 9

Same areas would be highlighted if replicated

Question 10

Why is a PET scan ethical?

Answer 10

Images taken outside of the body, non invasive

Question 11

Why is a PET scan high in validity?

Answer 11

Measures activity which is what it claims to measure

Question 12

Why is a PET scan unethical?

Answer 12

Injections are invasive

Question 13

Why can PET scans lack validity?

Answer 13

Hard to pinpoint exact areas of the brain so even if PET scans are clear, they are only valid up to a point as it is hard to claim from a scan exactly which part of the brain is performing which function

Question 14

What is an fMRI scan based on the idea of?

Answer 14

That brain activity is associated with blood flow in the brain and this activity is used to gather the info by the scanner to produce a picture

Question 15

What does an fMRI scan involve a person doing?

Answer 15

Putting your head in a large, very powerful electromagnet

Question 16

What happens inside the magnetic field of an fMRI?

Answer 16

The nuclei within the hydrogen molecules in water align themselves with the direction of the magnetic field

Question 17

What happens as neural activity increases in the brain of fMRI?

Answer 17

Blood flow increases in the active areas to keep up with the demand for oxygen which is carried to the neurons in haemoglobin within red blood cells

Question 18

What happens when haemoglobin carries oxygen in fMRI?

Answer 18

It repels a magnetic field and when deoxygenated it will follow the same direction of the magnetic field

Question 19

What does deoxygentated blood do in fMRI and why is this significant?

Answer 19

Causes disturbances to the magnetic field, whereas oxygenated blood doesn’t, these changes will create an image

Question 20

What are more active parts of the brain like in fMRI?

Answer 20

More active part of the brain = more oxygen = less magnetic field disturbances = signal measured for longer

Question 21

How long does an fMRI take?

Answer 21

2 hours

Question 22

Strengths of fMRI?

Answer 22

• Identifies function
• More ethical than surgery
• Scientific, replicable and reliable

Question 23

Weaknesses of fMRI?

Answer 23

• Brain never at rest, can’t isolate regions
• Lacks ecological validity
• Risk for people with pacemakers due to magnetic field