MRI/ fMRI Lecture

Question 1

Basic Principles of fMRI

Answer 1

H molecules spin in line with a magnetic field

• add an electromagnetic pulse to math the frequency of radio waves
• because H molecules want to get in line with the magnetic field they release radio waves to reach equilibrium

Question 2

Why if fMRI ideal for seeing brain structures

Answer 2

cells in brain are coated with myelin (fat)

which appears bright on an fMRI

Question 3

Why do you need a baseline for fMRI studies

Answer 3

A baseline acts a control in order to subtract all brain functions from the one that is responding to the test stimuli
-measuring blood flow influx in brain

Question 4

2 Experimental designs for fMRI

Answer 4

BLOCK

• simple and efficient
• 2 condition alternating block design for best results … switch between stimuli
• ideal length: 16 s (takes 12-14 s for blood influx to peak)

EVENT RELATED
-when you want to observe behaviour and timing of language processing or if you want your stimuli to be unpredictable

Question 5

Voxel

Answer 5

each volume is divided into stacks of slices and each slice is made up of voxels

Question 6

What would a t-test measure in an fMRI test

Answer 6

it would compare level of activation of baseline and task. the value reflects how different they are in that particular voxel

Question 7

what would a correlation test give you?

Answer 7

a value at each voxel to show you how well that voxel’s activation matches the model you’re testing

Question 8

fMRI does not reflect brain function (T/F)

Answer 8

TRUE

Question 9

Advantages of fMRI

Answer 9

non invasive
high spatial resolution
demonstrates brain’s functional connectivity (networks)

Question 10

Disadvantages of fMRI

Answer 10

low temporal resolution
expensive
indirect measure of neural activity
easy for experimenter to make mistake