2d. Techniques used to study brain

Question 1

CAT scans

Answer 1

Computerized Axial Tomography. Radiology technique that creates clear images of deep internal structures of the body

Question 2

What can CAT scans see?

Answer 2

Produces detailed images of hard and soft tissues, blood vessels and bones

Question 3

How does CAT scans work?

Answer 3

Uses cross sectional images that are compiled to form a 3D image. Contrast dye helps highlight certain areas like blood vessels

Question 4

Uses of CAT scans

Answer 4

Post-trauma head damage, blood clot, tumors, fluid in brain

Question 5

Advantages of CAT scans

Answer 5

• Less expensive than MRI
• More detailed than xrays
• Widely available
• Very clear
• Fast and non-invasive

Question 6

Disadvantages of CAT scans

Answer 6

• Exposed to high doses of ionizing radiation
• Requires breath holding
• Pregnant ladies should avoid

Question 7

MRI

Answer 7

Magnetic resonance imaging

Question 8

How does MRI work

Answer 8

• Uses strong magnets to create unified field that hydrogen protons follow
• H atoms emit energy when placed in field so machine captures location

Question 9

Advantages of MRI

Answer 9

• Non-invasive
• No radiation exposure
• High spatial resolution

Question 10

Disadvantages of MRI

Answer 10

• Metal is attracted to magnet
• Expensive
• Problematic for claustrophobics
• Lot of noise and one has to be still

Question 11

fMRI

Answer 11

Functional magnetic resonance imaging

Question 12

What do fMRIs use?

Answer 12

BOLD signals (Blood-oxygen level dependent) where oxy blood repels magnetic fields and deoxy blood is weakly attracted creating a gradient

Question 13

How do fMRI images look like?

Answer 13

Different colours represent gradient eg. Yellow is low activity and red is high

Question 14

What idea does fMRI rely on?

Answer 14

Idea that when brain cells use energy, there is more blood flow to that region to provide oxygen

Question 15

Use of fMRI

Answer 15

LoF and neurobehavioral disorders

Question 16

Advantages of fMRI

Answer 16

• No radiation exposure
• Able to record signal all over the brain
• Used to localize function

Question 17

Disadvantages of fMRI

Answer 17

• Localization is complex
• Costly and lengthy
• Metal implants attracted
• Claustrophobia

Question 18

PET scans

Answer 18

Positron Emission Tomography scans where blood flow is indicator of activity

Question 19

How does PET work?

Answer 19

Radioactive tracer is ingested and it binds to glucose. Scanner registers frequencies emitted and shows which brain area is more active

Question 20

Uses of PET

Answer 20

• Cancer cell identification

- Tumours

Question 21

Advantages of PET

Answer 21

• Spatial resolution
• Small and portable
• Usable on small animals
• Demonstrates biochemical changes

Question 22

Disadvantages of PET

Answer 22

• Very slow process

- Exposed to radioactivity

Question 23

EEG

Answer 23

Electroencephalography.

Question 24

What concept does EEG rely on?

Answer 24

Neurons in our brain use small electrical and chemical impulses to communicate. If large groups of neurons fire at the same time, electric potential can become detectable

Question 25

Does EEG give structure of brain?

Answer 25

No. Only function

Question 26

Uses of EEG

Answer 26

Epilepsy, seizures, head injury, encephalitis

Question 27

How is EEG done

Answer 27

Small electrodes are attached to scalp using glue or cap. Electrodes are connected to an EEG monitor. Takes two electrical impulses and outputs difference

Question 28

Advantages of EEG

Answer 28

- Changes can be seen in real time - Cheaper - Silent

Question 29

Disadvantages of EEG

Answer 29

- Only shows current results - Can trigger epilepsy - Hard to figure out where electrical activity is coming from