Neuroimaging techniques used PP Flashcards
Unit of measurement for electrocorticogram
Millivolts
Unit of measurement for EEG
Microvolt
2 recording techniques for EEG measurement
Monopolar
Bipolar
Electrode placement in monopolar recording technique
One active electrode in good contact with skin over area of interest
One reference electrode on relatively inactive area (ex tip of nose)
Name for electrode placement in monopolar recording technique
10-20 system
Electrodes are placed 10% or 20% between standard points
Electrode placement in bipolar recording technique
Two active electrodes are placed over cortical areas of interest
Leads record algebraic sum of the electrical potentials
No reference electrode
Disadvantage of bipolar recording technique
Produces record of combined activity at 2 locations
Which applications is the bipolar recording technique used in?
Research application (not clinical)
What can EEG resting state activity detect?
Changes due to disease
Advantages of EEG
Excellent temporal resolution to millisecond level
Cheap
Well tolerated
Widely available
Disadvantages of EEG
Poor spatial resolution
Complex analytical procedures
What kind of imaging is MRI?
Structural imaging
Name 2 kinds of dynamic imaging
PET
EEG
4 kind of functional imaging
Functional MRI
PET
MEG
EEG
Which imaging technique has the highest spatial resolution?
MRI
What does MRI relaxation refer to?
The process by which protons release the radio frequency energy and return to their original configuration
How many relaxation times can be measured in MRI?
2, spin-lattice(T1) and spin-spin(T2)
And for fMRI also T*
What is PET based on?
radioactive decay scheme of positrons
2 types of radio tracers used in PET
Fluorine based (long half life)
Carbon or oxygen based (short half life)
Which imaging technique has the lowest spatial resolution?
Electroencephalography (EEG)
Which imaging technique has the highest temporal resolution?
EEG
Which imaging technique has the lowest temporal resolution?
PET$
What does functional neuroimaging techniques exploit?
Biochemical and biophysical transient changes that occur in the brain cells
What general assumption is cognitive neuroimaging based on?
That complex cognitive tasks are the result of simpler operations
2 data analysis that allow to detect physiological changes related to psychological events
Subtraction
Statistical parametric mapping
What does evidence from PET studies show changes in as response to motor, sensory and cognitive tasks?
Brain blood flow
What does fMRI use?
Changes in magnetic properties of oxygenated and deoxygenated hemoglobin
How long is the delay between stimulus presentation and detection of the hemodynamic response?
4000 ms
What is echo planar imaging (EPI)?
MRI method used to acquire fast one-shot images
What is BOLD contrast?
Blood Oxygen Level Dependent contrast
2 types of design used by functional neuroimaging studies and which technique uses them
Block design (PET and fMRI)
Event-related design (EEG and fMRI)
How does block design work?
Baseline
Activation
Baseline
How does event related design work
Random mix between event 1 and event 2
Limitation of block design
Trails can only be presented in a fixed order
Advantages of event-related design
Random order of trails
Subjective or post-hoc classification of trials
Statistical models can be more accurate than block design
Disadvantages of event-related design
Less efficient in detecting potential effects
Some psychological processes are better measure during a block design (ex task switching)
