fMRI and Cognition

Question 1

MRI scans- shows structure of the brain

Answer 1

• Atoms are like constantly spinning magnets
• These atoms align in a scanner’s magnetic field
• Then you send in radio waves to make them face in a new direction
• When they relax and return to their previous alignment, they emit energy
• This energy is what the scanner uses to create an image

-Hydrogen atoms in different tissues have different relaxation times and can be identified separately
- The lower the water content of an area, the fewer hydrogen atoms there will be emitting signals
-The weaker the signal, the darker the area appears on the scan

Question 2

fMRI- shows function

Answer 2

• Measures blood flow to the brain
• Blood contains haemoglobin which contains iron (magnetic)
• Deoxygenated blood is affected by a magnetic field differently than oxygenated blood
• When neurons are active, they burn energy. This is automatically replenished via oxygen carried by haemoglobin in the blood stream
• Active parts of the brain contain more oxygen-rich blood
• By measuring the BOLD (Blood Oxygen Level Dependent) response by the MRI scanner, we can work out which parts of the brain were active recently

Question 3

fMRI 2

Answer 3

Haemoglobin is diamagnetic (weak magnetic field) when oxygenated but paramagnetic (strong magnetic field) when deoxygenated

Question 4

fMRI advantages

Answer 4

• Excellent spatial resolution
• Reasonable temporal resolution
• Non-invasive
• Tells us which parts of the brain are used in tasks

Question 5

fMRI disadvantages

Answer 5

• Expensive
• Claustrophobic

Question 6

How does culture impact face processing

Answer 6

Both Japanese and white American participants performed better on same vs other culture mental state coding from the eyes

Performance pattern was mirrored by culturally tuned neural activity in the bilateral pSTS (an area known for mental state reasoning and eye gaze perception)