User Tutorial:Obtaining Mu Rhythm Parameters in an Initial Session

Although the basic properties of the Mu rhythm are identical for all human subjects, its spatial pattern and its exact frequency will differ. Thus, it is necessary to obtain these individual parameters prior to any feedback experiments, in an initial session.

Experimental Design

In the initial session, the subject is instructed to imagine hand and/or feet movements according to a pre-defined pattern. To identify a subject's Mu Rhythm, the amplitude of the EEG signal is then taken for different frequency bands, and correlated with the instructions. Across frequencies, this results in a line spectrum; across electrode locations, the result is a spatial distribution of activity.

Performing the Initial Session

• Start batch/StimulusPresentation.bat.
• Load parms/mu_tutorial/Screening.prm.
• Additionally, load the configuration file appropriate for your amplifier (parms/amplifiers/gUSBamp.prm or gMOBIlab.prm).
• In the operator module, click "Config".
• Under the "Storage" tab, enter the subject's initials into the "SubjectName" parameter.
• Switch to the "Source" tab; into the "ChannelNames" parameter, enter the electrode locations corresponding to the amplifier channels, as a white-space separated list, e.g.

Fz CPz Cz CP3 ...

• Instruct subject
• Click "Start".

Analyzing the Initial Session

• Use NN tool to obtain a feature map.
• Look for vertically dominant structures at 9-15|18-30 Hz to identify the Mu Rhythm.
• Check the topography for plausibility (compare to typical topographies).
• Determine whether you have the pattern of a radial or tangential source orientation.
• Determine the Mu Rhythm base frequency (must be exactly half of the second peak if unsharp).