Good afternoon,
I have the head models of 80 subjects from an old protocol that I would like to use on a new protocol. The head models were done on different raw eeg data, the same subjects, collected all at the same time.
So, I would like to know if I can use these previously created head models done with OpenMEEG BEM to analyze the other tasks (new protocol)? Or are the head models dependent on the raw file?
Let me know if you have any questions or need more info.
Thanks a lot,
Gloria
Hi,
The head models depend on the geometry or the shape of the head, the cortex (the number and the location of the dipoles), the conductivity of the tissues, and the location and number of the channels.
If you change one of these parameters you need to re-compute the "head model",
So, if you have the same subjects (same MRI), and your raw data contains the same channels (same numbers of and locations), then you can use the previous head models in your new protocols, otherwise, you need to recompute them.
Indeed, if the anatomy and the structure of the channel files remains the same, you can simply copy the head models.
It also depends how old these files are. If they were computed years ago, we might have fixed important bugs since. It could be interesting to re-import the anatomy and recompute the forward model for one subject, to make sure it is almost the same as the previous one.
The models were created in January of 2018. I will try with one subject then.
To copy them should I copy-paste the file into my protocol and that's all?
Thanks a lot for both of your answers!
-Gloria
Yes, a simple copy-paste, followed by a manual reload of the subject (or the entire protocol) so that the head models appear in the database explorer.
(this is valid if there is strictly no change in the list of channels, the anatomy, the position of the fiducials NAS/LPA/RPA in the anatomy...)