Hi,
In order to save channels, as our amplifier limit is 128, I often disconnect the middle sEEG contacts going through the white matter. As a result, I end up with electrodes recording from less contacts than their configuration (say, a 10-contact electrode may end up recording from 6 channels 1-3 & 8-10). This creates a discrepancy between the recorded sEEG file and the implantation map in Brainstorm, as the latter expects more channels. Is there a way around that? Can I erase/de-activate specific contacts from each sEEG group in order to match the recording?
Thank you,
Vasileios Kokkinos
Hello,
This is actually a common case in sEEG. If I understand correctly your question, you have two ways of doing this:
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If you link your recordings and then edit the sEEG positions, the number of contacts actually present on the electrodes should not matter. Set the tip of the electrode at the first contact, even if it is not recorded. This is the case described here:
http://neuroimage.usc.edu/brainstorm/Tutorials/Epileptogenicity#Editing_the_contacts_positions
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Otherwise, you can start with an empty list of electrodes with the menu “SEEG/ECOG implantation”, as described in the same tutorial section. Then export it to a text file (which will include all the contacts), and load it in your recordings with the menu “Add EEG positions”, as illustrated in this tutorial: http://neuroimage.usc.edu/brainstorm/Tutorials/Epileptogenicity#Import_the_contacts_positions
This requires more steps of manipulation, but has the advantage of editing the implantation map independently of the recordings processing, so that it can be reused for recordings with different selections of contacts, or by different people.
Make sure your version of Brainstorm is up-to-date, as these tools were improved in February-March.
Does it help?
Francois
Thank you Francois.
The second solution turned out to be more practical, as I have a solid overview of what’s recording and what not.
Vasileios.