User Tutorial:Configuring Online Feedback

This tutorial step assumes that you have performed and analyzed an initial session. Now you are going to create a subject-specific parameter configuration for on-line feedback.

Starting up BCI2000

Start BCI2000 using the appropriate batch file at batch/CursorTask_<YourAmplifier>.bat. You might consider creating a link to this file on the desktop.

Subject-Specific Parameters

In the next step, we will construct a full parameter file that is specific to that subject:

• In the configuration window, click Load Parameters to load parms/mu_tutorial/MuFeedback.prm.
• Additionally, load your amplifier configuration from parms/fragments/amplifiers.
• When you have a separate monitor for experimenter and subject, load the parameter file at parms/fragments/stdlib/DualMonitor.prm.
  • In your system's display properties configuration, make sure that the subject's monitor is configured to be located to the right of the main monitor.
  • Make sure the WindowLeft parameter matches the main monitor's actual pixel width.
  • You may need to adapt WindowTop, WindowWidth, and WindowHeight parameters as well; click "Set Config" to try the effect of your changes.
• Switch to the "Source" tab; for the "ChannelNames" parameter enter electrode locations corresponding to amplifier channels as a white-space separated list (e.g., Fz CPz Cz CP3 ...).
• Go to the Storage tab, and enter the subject's name or ID into the SubjectName parameter.
• Into the SubjectSession parameter, enter 002.

Configuring the Classifier

Subject-specific electrode location and mu rhythm frequency are part of the classifier's configuration. They are entered into the Classifier parameter on the Filtering tab; there, click the Edit Matrix button associated with the Classifier parameter.

1. Set Number of columns to 4, and Number of rows to 1 (or the number of features that you wish to use); then, click Set new matrix size to apply your changes.
2. In the first column (of the first row), labeled input channel, enter the location of the desired location, e.g. CP3. If you did not specify electrode locations when configuring the spatial filter, enter the channel number associated with the feedback electrode.
3. In the second column, labeled input element (bin), enter feedback frequency in Hz, immediately followed with Hz, as in 12Hz.
4. In the third column, enter the value 2 corresponding to the control channel for vertical control of the cursor.
5. In the fourth column, enter 1 as the weight.
6. Repeat steps 2-5 for each additional feature moving down a row each time (i.e., enter the 2nd feature on the 2nd row, etc...).
7. Finally, save your configuration to parms/subjects/mu_feedback/<Subject>002.prm, or whereever you find appropriate.

Next Step

In the next step, you will learn how to actually perform a Mu rhythm feedback session using the configuration created in the present step.

See also

User Tutorial:Mu Rhythm BCI Tutorial, User Reference:SpatialFilter, User Reference:LinearClassifier