Getting electrode coordinates after simulations

[Gabriel]

Hello,

I am currently working with ROAST to simulate electrode placements and brain electric fields. After running the simulation, I would like to retrieve the coordinates of the electrodes (in MNI or voxel space), but I haven’t found a method or an output file where these coordinates are stored. Could they be stored in the _seg8.mat file? Or should I exctract them manually using the mask_elec.nii file?
I have checked the documentation and several forums, but I wasn’t able to locate this information or figure out how to extract or convert the coordinates correctly.

Does anyone know of a workflow or script to access and extract electrode coordinates after the simulation has run?
Any help or advice would be much appreciated!

[Yu (Andy) Huang]

Hi Gabriel,

Electrode coordinates are not output by roast, but you can get them by loading the mask_elec.nii file where each placed electrode is marked by a unique number.

In the upcoming release of Roast V4, the transform from voxel space to MNI space (mri2mni) will be output in the log file and option file. For now you can compute the transform using data stored in _seg8.mat file.

Hope this helps.

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[Gabriel]

Hi,

Thank you very much for your previous advice—it has been very helpful. I have a follow-up question regarding electrode placement: Is it possible to place the electrodes Ex17 and Ex18 within the 10-10 EEG model in ROAST? Alternatively, is there an equivalent to these electrodes in the model (I was thinking perhaps Exx35 and Exx36)?

Thanks again for your invaluable support!

Best regards,
Gabriel