Practical EEG Flashcards
Data analysis practical
What is the difference between EEG and fMRI?
EEG: direct measurement of brain activity
(postsynaptic potentials), high temporal resolution
(WHEN), reference needed, portable, tolerance to
motion and relatively cheap
fMRI: BOLD signal is indirect measure of brain
activity (blood flow), high spatial resolution
(WHERE), scan environment +
magnetic field pose
restrictions (less
naturalistic) and expensive
Of what parts does analysing ERP data consists?
Part I: (pre)processing raw individual data
Part II: group level analyses (stats)
Different datasets!!
Pre)processing raw (individual) data
(Know what type of data you’re working with)
- Visually inspect your data
- Clean your data: filtering, rejecting artefacts etc
- Re-reference your data (not always necessary)
- Set markers to define time intervals
- Define, label, select conditions
- Plot and view ERP of different conditions/channels
Analyze data on group level
Different study design, dataset!
- Same preprocessing steps as individual data
- Visualize the data
- Run statistics (compare ERP amplitudes between
conditions) - Interpret findings
What does the amplitude and latency shows?
Amplitude: strength/ more neural resources
Latency: how often
What do early and later peaks show?
Early peaks: stimulus itself/concentration
Later peaks: motivation/cognitive processing
What is plotted on the Y-axis?
Voltage measured at each electrode
Where are the z-channels located and what does the ‘z’ stand for?
Z-channels are located in the middle of the head and ‘z’ (zero) is for the midline
Give a description of the X and Y-axis
X is the frequency and Y the Log of the Power Sepctral Density. This is a measure of HOW MUCH (power) a frequency is present in a signal - the higher the frequency the faster the wave
8-12 Hz is the alpha waves and 60 Hz is the noise of the electrical network
