User Tutorial:Performing an Offline Analysis of EEG Data

Although the basic properties of the Mu rhythm are identical for all humans, its spatial pattern and its exact frequency will differ. BCI2000 Offline Analysis helps to determine the frequencies and locations that correlate best with a given instruction.

Experimental Design

In this tutorial, we'll be considering three different data sets recorded from three different subjects. All the datasets referred to reside in data/samplefiles. Below is a list of the datasets we'll be using along with a description of the experiment:

Dataset	Description
eeg1.dat	In this session, the subject was asked to move both hands and both feet in a predefined pattern. The resulting data was recorded using BCI2000 and labeled such that TargetCode is equal to 1 when the subject is responding to the instruction to move both hands and 2 when the subject is responding to the instruction to move both feet.
meg1.dat
ecog1.dat

EEG Analysis

Let's begin with an offline analysis of dataset eeg1.

1. Open BCI2000 Offline Analysis. If this is your first time using BCI2000 Offline Analysis, you may want to review the instructions on how to install and run this application: User Reference:BCI2000 Offline Analysis.
2. Set the analysis parameters as follows:
   1. Analysis Domain: Choose "Frequency" in order to perform a frequency-domain analysis
   2. Acquisition Type: Choose "EEG" since the data we'll be working with in this section was recorded using an EEG.
   3. Data Files: Click the "Add" button and navigate to data/samplefiles. From there double-click or otherwise open the file named "eeg1.dat".
   4. Montage File: Leave this blank. The reason for doing so will be explained shortly.
   5. Target Condition 1: Enter the value "states.TargetCode == 1". This instructs BCI2000 Offline Analysis to search the data for sections where the TargetCode indicates that the subject was responding to the instruction to move both hands.
   6. Target Condition Label 1: The text entered here will be used to label data that is specific to condition 1. So, it would seem that entering the value "Both Hands" would be appropriate.
   7. Target Condition 2: Enter the value "states.TargetCode == 2". This instructs BCI2000 Offline Analysis to search the data for sections where TargetCode indicates that the subject was responding to the instruction to move both feet.
   8. Target Condition Label 2: The text entered here will be used to label data that is specific to condition 2. So, it would seem that entering the value "Both Feet" would be appropriate.
   9. Trial Change Condition Enter the value "states.IntertrialInterval == 1". This instructs BCI2000 Offline Analysis that the trial edges correspond to data samples where IntertrialInterval becomes 1 or is 1 and becomes something else.
   10. Spectra Channels: Leave this blank. The reason for doing so will be explained shortly.
   11. Topo Frequencies: Leave this blank. The reason for doing so will be explained shortly.
   12. Spatial Filter: Choose "Common Average Reference (CAR)". Typically, filtering the data with a simple spatial filter such as CAR results in sharper, more useful plots.
   13. Ignore Warnings: Unchecked
   14. Overwrite existing plots: If you have not yet run any analyses, this field should be disabled. If it is enabled, it is best for the purposes of this tutorial to leave it checked. Unchecking this box will instruct BCI2000 Offline Analysis to open new figures whenever it plots. This is useful if you want to compare the results of one analysis against another.