I am starting to re-learn Brainstorm after a long period away from it. I used to know how to register a set of EEG electrodes to the default anatomy, but now am almost completely lost. I currently have an R-Net with 64 electrodes, and I have its electrode positions in generic Cartesian and spherical coordinates. I do not have actual head coordinates of the electrodes or the fiducial points. I am looking for a version of the coordinates that has already been warped to fit to a head so that it is more closely aligned to begin with, but may have to use the spherical coordinates and manually warp them. Can someone please suggest a strategy to follow?
Do I have to load an EEG first before I can register the electrodes?
Thanks,
-Jeff Eriksen
Hi Jeff, as the R-Net is using the 10-20 system, you can the locations for the EEG electrodes on the default anatomy (e.g., ICBM152).
Right-click on the channel file (
) > Add EEG positions > ICBM152 > Generic > 10-10 65
If some of the electrodes are not found, try with a cap with more electrodes e.g., ASA 10-20 94
Usually yes, as the channel file is created at the moment of reviewing the raw data.
Hi Raymundo,
Your answers got me on the right path. I eventually remembered I had made a SET-file version of the raw EEG that has the correct montage and electrode positions in spherical coordinates. I was able to import that into BS. Now I need to manually position the electrode sphere and size it to match the MRI head surface, then extrapolate to the surface. I am having a problem with that, however - the translation controls do not work. I can rotate and resize, but not translate. Any reason you can think of for this to be happening?
Hi again,
Aside from my problem with translation of the electrode cloud during manual registration (previous message), it would make things much easier if I had a real head electrode digitization. BrnStm has them built in for the BrainProducts ActiCap and EasyCap, but not for the R-Nets. Did BrainProducts provide those, or were they contributed by users?
I have asked BrainProducts if they might have electrode location files for the R-Nets that they could send you. What format would they have to be in?
Solved! I figured out how to do it.
Add EEG positions -> NotAligned -> Generic -> ASA 10-05 343
Please ignore my last two posts.