Hello,
I am trying to import electrode positions to my channel file for raw data gathered with the 64 electrode EGI Hydrocel. While using ICBM152 default anatomy and trying to import the default positions for EGI 64 GSN, I get a message saying “no channel matching the loaded cap”. I have checked online and confirmed that the electrode map from my acquisition is identical to the EGI default layout. The channel file generated by my raw data is a 67 channels including the 64 electrodes, VREF, ECG, and ANNOTATIONS.
I have also tried loading the GSN .spf files downloaded from the EGI website for use in third party software. I encounter the same message of “no channel matching loaded cap” and my matlab often (not always) encounters an “invalid file identifier” error.
I do not have access to the .spf location files from my acquisition (though I’m sure they would likely work).
Any ideas on what is causing this and/or how I could fix it?
Thanks,
Brett
Hello,
If you link your EGI .raw file to the Brainstorm database, then right-click on the channel file > Add EEG positions > ICBM 152 > EGI > GSN Hydrocel 64, you should get a message that at least some of the electrodes where found.
Otherwise, the naming of the channels in your .raw files does not match the EGI standard naming (E1…E64, or E01…E64).
The electrodes positions are matched with the channels using the labels of the electrodes.
To get the list of the channel names as available in your .raw file: right-click on your channel file > Edit channel file.
Please let me know what is the cause of the mismatch. Maybe there is something that I need to update to take into account new modifications in the NetStation software.
Francois
Hi Francois,
Using the ICBM 152 positions is when I get the "no channels match", so I think the labeling of electrodes in Netstation must have changed. Here is my channel file:
But its odd because as I said, using EGI's location files directly from their website also wasn't working. I will check to see if Netstation is actually what we used and get back to you.
Okay, so I was using an EGI 64 electrode Hydrocel (I’m so sorry for the confusion, the device was from another lab and the info they gave me was incorrect). My data acquisition software was NetStation version 5.2, which is not the current version of Netstation so it must be outdated in comparison to Brainstorm. I will try to get a copy of my position files from our data acquisition computer.
Thanks,
Brett
The reason for which you don’t have the expected naming of the channels is because the files were exported from the NetStation using the EDF file format, instead of the binary .raw format from EGI (+ .epoch files if applicable). If you can, export again your recordings in EGI .raw format, and it should solve your problem.
Otherwise, you will need to rename the channels in the channel file, to match the template positions (I guess you just need to add “E” in front of all the electrode names). You can do this once, and then copy-paste the channel file to your other folders/subjects.
Great, using .raw worked thank you so much!
You do need to update the naming of electrodes 1-9 on the Hydrocel template to be E1, E2, E3, etc. without the leading 0’s because I had to fix them.
Hi Brett,
The default naming for the menu “Add EEG positions > ICBM152 > EGI > GSN HydroCel 64” does not include the 0.
The electrodes are named E1, E2, …
Do you need a template where the electrodes are named E01, E02, …?
(I previously got requests to add this for the 128 and 256 caps)
Francois
Sorry. Yes, I got this backwards, My Electrode names in my .raw were E01, E02… and your template does not include the 0.
Done: I’ve added the E01 template in Brainstorm.
Update Brainstorm to get these new options.
