research methods (brain imaging) Flashcards
what are the 5 kinds of brain imaging?
MRI
MEG
fNIRS
EEG
PET
how many kinds of MRI are there?
- sMRI
- fMRI
- dMRI
what does the number in a voxel represent?
the bigger the number, the ___________ the voxel
voxel intensity; brighter
which of the 3 MRIs is also known as T1-weighted imaging?
sMRI
sMRI is primarily used to study ____ whereas dMRI is used to study _____-related microstructure.
GM; WM
what are the 2 measurements in dMRI?
- FA (fractional anisotropy)
- MD (mean diffusivity)
what do FA and MD images show? where are they from?
from raw dMRI images.
- FA shows direction of water movements in WM
- MD shows overall amount of water diffusion/movement in WM
high/low levels of FA indicates compromised microstuctural integrity. why?
low.
water movement in WM is highly directional, so should be high FA. Low FA in WM indicates compromised microstural integrity.
*FA highest in WM, low in GM, lowest in ventricles/CSF
high/low levels of MD indicates compromised microstuctural integrity. why?
high.
MD is non-directional. Lowest in WM, high in GM, highest in ventricles/CSF.
what does fMRI measure?
brain activity from GM regions
- measures blood-oxygen-level-dependent (BOLD) activity
- changes in deoxyhemoglobin driven by localised changes in brain blood flow and blood oxygenation
during fMRI scan, multiple brain volumes are acquired across short intervals (from ___ to ____).
duration of these intervals: _______________
0.7s-3s; temporal resolution
fMRI analyses always involve a constrast between 2 conditions only. cannot be more or less.
true or false?
false. at least 2.
the 2 basic conditions of an fMRI study are?
what is the point of the control?
- control task - act as baseline activation level, to compare to activity in the task of interest, as everyone has different baseline activation levels.
- task of interest
what does EEG stand for?
electroencephalogram
what does EEG (electroencephalogram) measure?
electrical activity in the brain during a very brief event
what does high temporal resolution mean?
which imaging method has higher temporal resolution, fMRI or EEG?
data can be collected across very short intervals
EEG
what is subliminal priming?
Subliminal priming refers to the process by which a stimulus is presented below the threshold of conscious awareness, yet still influences a person’s thoughts, feelings, or behaviors.
The idea is that the brain can process this information without the individual being consciously aware of it.
what is a disadvantage of EEG?
poor spatial resolution - difficult to point out exactly where activity is coming from
what is ERP?
Event-Related EEG Potential - a measure used to examine brain activity in response to specific events or stimuli.
what does MEG stand for?
magnetoencephalogram
which other brain imaging method is MEG similar to? compare them.
EEG (electroencephalogram)
- EEG detects electrical acticity of multiple active neurons while MEG detects magnetic field of multiple active neurons
- electrical and magnetic fields are perpendicular to each other. the corticol folds in the brain meant that activity in different parts of the fold is sensitive to different methods
- both have high temporal reso and low spatial reso
- EEG has lower spatial reso (10mm) than MEG (3mm)
- EEG detects activity on cortical surface while MEG can detect activity from subcortical regions
what is SQUID (superconducting quantum interference device)?
superconducting sensor in MEG scanners to detect the very weak magnetic field activity in brain
what is fNIRS?
how does it differ from fMRI?
functional near-infrared spectroscopy
- detect changes in blood ocygenation levels using infrared signals
- needs detector and emitter (emitter emits infrared signals and detector detects reflected signals)
- amt of signal absorbed/reflected by brain tissue caries with blood oxygenation level
- high temporal reso, low spatial reso
differs from fMRI:
- fMRI detects changes in blood oxygenation level via BOLD signals
- fMRI have higher spatial reso than fNIRS
- both have similar temporal reso
how many kinds of brain stimulation are there?
TDCS (transcranial direct current stimulation)
TMS (transcranial magnetic stimulation)
Deep brain stimulation
