Basic EEG processing

Basic EEG processing allows you to re-reference and do high-pass filtering of your selected EEG data recordings and obtain a .csv file with pre-processed data. Note: If your records contain event markers/event labels, this pipeline will add a column with event markers corresponding to each timestamp to the output - this aids in identifying corresponding timestamp for each marker.

Slew limit

You can set a slew rate limit to control the EEG signals between successive samples, up to a maximum value. Large voltage step changes from one sample to the next sometimes occur due to electrostatic discharge from the subject (participant), headset movements, or other artifacts. The effect of voltage step changes on filtered signals, and fast Fourier transform (FFT) epochs can artificially persist for a long time after the event. Setting a maximum slew rate limits the extent of step changes and reduces its impact without significantly affecting the EEG signal components.

The default slew rate in Analyzer is 30 microvolts. However, you can enter any positive value here.

Re-Referencing

Data processed by Analyzer can be re-referenced to an aggregate of all the data selected. The available aggregate functions are:

• Mean

• Median

• Interquartile mean

• None (does not perform any re-referencing)

Filter Coefficients

We recommend using default values for second order high-pass filter of 3dB at 0.5Hz which have been set for you. If you are experienced with filter coefficients you can change the values.

Once you have set the values for basic EEG processing, click on the Start button. Analyzer will then process your selected data recordings.

Results

While your data is processing, the job management page will open. You can download your results file when the job is complete.

To understand the fields in your .csv outputs please see the csv outputs section.