Using fMRI to study cognitive neuroscience

Question 1

What can you measure in the brain?

Answer 1

Blood flow
Oxygen level
Electrical activity
Magnetic field
Neurotransmitter

Question 2

What is Functional magnetic resonance imaging (fMRI)?

Answer 2

A strong magnet detects slight changes in local magnetic fields caused by changes in blood oxygenation
Oxygen level in blood translates how active a brain area is

Question 3

What does active brain tissue use more of?

Answer 3

Blood i.e. glucose/O2

I.e. Hemodynamic response (HDR)

Question 4

What does fMRI measure?

Answer 4

Blood Oxygenation Level Dependent (BOLD) signal

Changes in deoxygenated and oxygenated haemoglobin ratio

Question 5

What is the difference between deoxygenated and oxygenated haemoglobin?

Answer 5

Different magnetic properties

Question 6

What regions do the functional face localiser scan pick up?

Answer 6

Occipital face area, fusiform face area, posterior superior temporal sulcus, amygdala, posterior cingulate cortex and medial orbitofrontal cortex, and inferior frontal gyrus

Question 7

What are things to consider when designing an fMRI experiment?

Answer 7

Haemodynamic response- astrocytes function as link between synapses and blood vessels
Temporal resolution only sufficient for longer trials

Question 8

What is the fMRI technique?

Answer 8

Strong magnet to detect oxygen changes in blood; BOLD signal, haemodynamic response
–> indirect measurement of neuronal activty

Question 9

What are the resolutions for fMRI?

Answer 9

Spatial resolution- excellent

Temporal resolution- okay for longer trials or blocks

Question 10

What are the limitations of fMRI?

Answer 10

No ferromagnetic objects
Discomfort for larger participants or individuals suffering from claustrophobia
Long scanning time

Question 11

What is Event Related Potentials?

Answer 11

Electrodes on scalp surface measure electrical activity generated by neurons

Question 12

What is measured in ERPs?

Answer 12

Secondary current from many neurons

We measure the difference between “target” electrode and a neutral “reference” electrode

Question 13

What is the resolution of ERPs?

Answer 13

Spatial resolution- okay-poo, depends on number of electrodes used; signal comes from many neurons
Temporal resolution- excellent (ms)

Question 14

What are the limitations of ERPs?

Answer 14

Long preparation time and long experiments; many trials needed for averaging
Artefacts caused by movement, eye blinks etc

Question 15

What is magnetoencephalography (MEG)?

Answer 15

Measures magnetic field that is generated by neural activity

Question 16

What do magnetic fields on surface of scalp measured by what detectors?

Answer 16

Superconducting
Quantum
Interference
Device

Question 17

What technique is measured for MEG?

Answer 17

SQUIDs measure the magnetic field on surface of scalp (generated by primary current)

Question 18

What is the resolutions of MEG?

Answer 18

Spatial resolution- good, large number of detectors

Temporal resolution- excellent

Question 19

What are the risks/discomforts of MEG?

Answer 19

Artefacts caused by movement, ferromagnetic objects etc
Long scanning time
Expensive

Question 20

What can be used to measure blood flow?

Answer 20

Transcranial Dopler Sonogrpahy (fTCD)

Question 21

What can be used to measure oxygen level?

Answer 21

fMRI

Question 22

What can be used to measure electrical activity?

Answer 22

EEG/ERP

Question 23

What can be used to measure magnetic field?

Answer 23

MEG

Question 24

What can be used to measure neurotransmitters?

Answer 24

Positron Emissions Tomography (PET)