Module 2 - Part 2

Question 1

How is fMRI a functional imaging technique?

Answer 1

It tells us which brain areas are active during a task

Question 2

How does fMRI work?

Answer 2

It measures the level of oxygenated blood and deoxygenated blood

• if a brain area is active, it required more oxygenated blood
• once the brain region uses the oxygen, the blood becomes deoxygenated
• this deoxygenated blood distorts the magnetic signal; but oxygenated blood receives a good magnetic signal

Question 3

What is attenuation?

Answer 3

The reduction of a signal

• the more dense, the more attenuation
• the less dense, the less attenuation

Question 4

What is a hemodynamic response?

Answer 4

The time it takes the brain to ask for oxygenated blood and use it

Question 5

What is the time frequency of fMRIs?

Answer 5

the hemodynamic response time is between 8-10 seconds long, so we are not able to quickly compare signals

Question 6

What is a voxel?

Answer 6

A 3D pixel (like minecraft)

Question 7

What is the most critical step when an fMRI experiment is going to be run?

Answer 7

The selection of the baseline task (you have to start with the brain’s most basic function, i.e. just not doing anything, then get participant to fixate on a cross, then look at faces, etc)

Question 8

What is fMRI multivoxel pattern analysis (MVPA)?

Answer 8

• it provides info about a pattern of activity but also patterns across brain regions
• each category of an object is associated with a unique pattern of activation (ex. furniture vs. faces vs. animals)
• the algorithm sets a boundary of prediction between the two variables

Question 9

What kind of category seems to be important to the brain?

Answer 9

Semantic categories

Question 10

What do fMRI resting state approaches focus on?

Answer 10

They examine patterns of brain activity in the absence of a task

Question 11

What is default mode network?

Answer 11

The pattern of brain activation when brain is at rest

- this varies with different pathologies like Alzheimer’s

Question 12

What are the advantages of doing fMRI resting state approaches?

Answer 12

• it doesn’t require a degree of cognitive ability in the participant
• only a short session is required (10-15 mins)

Question 13

What are the advantages of using fMRI?

Answer 13

• it is a functional technique
• high spatial resolution
• higher temporal resolution than PET
• non-invasive
• patterns of activity

Question 14

What are the disadvantages of using fMRI?

Answer 14

• expensive
• claustrophobic
• noisy
• poor temporal resolution compared to EEG and ERP
• identifies multiple brain regions
• it is an indirect measure of brain activity

Question 15

What brain area seems to be responsible for language switching?

Answer 15

The caudate nucleus

Question 16

What is an ERP?

Answer 16

It is an event related potential (the action potential from a stimulus)

Question 17

What does EEG measure?

Answer 17

The neural activity of thousands of neurons

Question 18

Describe ERPs?

Answer 18

• ERPs must be averaged

- they are negative and postitve

Question 19

What is P300 associated with?

Answer 19

ERP pattern when higher order processes are involved

Question 20

What is associated with N400?

Answer 20

ERP associated with semantic processing (400-600ms)

- semantic relationship: does the word fit? if it doesn’t, this spike is higher

Question 21

What are the advantages of ERP?

Answer 21

• direct measurement of mass neuronal activity
• high temporal resolution
• non-invasive

Question 22

What are the disadvantages of ERP?

Answer 22

poor spatial resolution