Flashcards in Using fMRI to study cognitive neuroscience Deck (24):
What can you measure in the brain?
What is Functional magnetic resonance imaging (fMRI)?
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
What does active brain tissue use more of?
Blood i.e. glucose/O2
I.e. Hemodynamic response (HDR)
What does fMRI measure?
Blood Oxygenation Level Dependent (BOLD) signal
Changes in deoxygenated and oxygenated haemoglobin ratio
What is the difference between deoxygenated and oxygenated haemoglobin?
Different magnetic properties
What regions do the functional face localiser scan pick up?
Occipital face area, fusiform face area, posterior superior temporal sulcus, amygdala, posterior cingulate cortex and medial orbitofrontal cortex, and inferior frontal gyrus
What are things to consider when designing an fMRI experiment?
Haemodynamic response- astrocytes function as link between synapses and blood vessels
Temporal resolution only sufficient for longer trials
What is the fMRI technique?
Strong magnet to detect oxygen changes in blood; BOLD signal, haemodynamic response
--> indirect measurement of neuronal activty
What are the resolutions for fMRI?
Spatial resolution- excellent
Temporal resolution- okay for longer trials or blocks
What are the limitations of fMRI?
No ferromagnetic objects
Discomfort for larger participants or individuals suffering from claustrophobia
Long scanning time
What is Event Related Potentials?
Electrodes on scalp surface measure electrical activity generated by neurons
What is measured in ERPs?
Secondary current from many neurons
We measure the difference between "target" electrode and a neutral "reference" electrode
What is the resolution of ERPs?
Spatial resolution- okay-poo, depends on number of electrodes used; signal comes from many neurons
Temporal resolution- excellent (ms)
What are the limitations of ERPs?
Long preparation time and long experiments; many trials needed for averaging
Artefacts caused by movement, eye blinks etc
What is magnetoencephalography (MEG)?
Measures magnetic field that is generated by neural activity
What do magnetic fields on surface of scalp measured by what detectors?
What technique is measured for MEG?
SQUIDs measure the magnetic field on surface of scalp (generated by primary current)
What is the resolutions of MEG?
Spatial resolution- good, large number of detectors
Temporal resolution- excellent
What are the risks/discomforts of MEG?
Artefacts caused by movement, ferromagnetic objects etc
Long scanning time
What can be used to measure blood flow?
Transcranial Dopler Sonogrpahy (fTCD)
What can be used to measure oxygen level?
What can be used to measure electrical activity?
What can be used to measure magnetic field?