[FieldTrip] Probelm with the EEG inverse problem

[Schoffelen, J.M. (Jan Mathijs)]

Hi Sara,

It looks as if the example/tutorial code is out-of-sync with the fieldtrip code (assuming that you are working with a recent version).
The error itself may be solved if you register the MRI image to a supported coordinate system first (i.e. before reslicing etc), using ft_volumerealign with cfg.method = ‘interactive’.

Good luck,
Jan-Mathijs


On 11 Apr 2024, at 17:42, Sara Cinelli via fieldtrip <fieldtrip at science.ru.nl<mailto:fieldtrip at science.ru.nl>> wrote:

Hello,
I would like to explain my problem. I am referring to the tutorial presented in this page: https://www.fieldtriptoolbox.org/workshop/natmeg2014/dipolefitting/#compare-the-eeg-and-meg-dipole-fits<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.fieldtriptoolbox.org%2Fworkshop%2Fnatmeg2014%2Fdipolefitting%2F%23compare-the-eeg-and-meg-dipole-fits&data=05%7C02%7Cfieldtrip%40science.ru.nl%7C047378e1b34c4c158e3b08dc5abd5303%7C084578d9400d4a5aa7c7e76ca47af400%7C1%7C0%7C638485016381261688%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=qfO01iA1QqLUCQw2YMp1kr5IEClcgD0N5RYv39PrqEU%3D&reserved=0>
The issue is that, copying the code in this page, there is an error that I don't understand:

Construct the MEG volume conduction model<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.fieldtriptoolbox.org%2Fworkshop%2Fnatmeg2014%2Fdipolefitting%2F%23construct-the-meg-volume-conduction-model&data=05%7C02%7Cfieldtrip%40science.ru.nl%7C047378e1b34c4c158e3b08dc5abd5303%7C084578d9400d4a5aa7c7e76ca47af400%7C1%7C0%7C638485016381261688%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=nKhusn27s51IEpHLoyojjOXBX%2FuWO6N3D6hjZ0MSgjM%3D&reserved=0>

Now that we have the anatomical MRI coregistered and resliced in to isotropic<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FIsotropy&data=05%7C02%7Cfieldtrip%40science.ru.nl%7C047378e1b34c4c158e3b08dc5abd5303%7C084578d9400d4a5aa7c7e76ca47af400%7C1%7C0%7C638485016381261688%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=TOx8IBtLmLgM0gdRi5DvhEuC8mv3f56AdZkmCNhy4aU%3D&reserved=0> voxels, we proceed and segment the brain, skull and scalp tissue.

cfg           = [];
cfg.output    = {'brain', 'skull', 'scalp'};
mri_segmented = ft_volumesegment(cfg, mri_resliced);


When I run the function ft_volumesegment these errors appears:

Error using ft_affinecoordinates
converting from scanras to acpc is not supported

Error in ft_convert_coordsys (line 169)
  initial = ft_affinecoordinates(object.coordsys, target);

Error in ft_volumesegment (line 301)
    mri = ft_convert_coordsys(mri, 'acpc');



Hope you can help me understanding this issue.


kind regards,

Sara

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https://doi.org/10.1371/journal.pcbi.1002202

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