Source grid (Group analysis)

1

Hi Francois,

I am currently trying to do source localization using a volume source model for a group of subjects. I am using EEG data. I was following the tutorial (https://neuroimage.usc.edu/brainstorm/Tutorials/CoregisterSubjects#Volume_source_models). However, once I create the source grid in the group analysis folder and try and compute the head model for the subjects, I am not getting the option of "use template grid for group analysis". Could you please let me know how I should proceed.

Thank you so much.

Best,
Ami

3

If you the option "use template grid" is not visible: you are trying to compute a head model directly in the "group analysis" subject, and this is not meant to work this way. In this case, you can just compute the head model once, with a single grid available only in the group analysis subject.

If you configured your protocol to use shared anatomy or shared channel files between subjects (not recommended), then this option is not applicable.

If you see the option but it is not enabled, you should have some additional text explaining why this menu is disabled: No head model available in "Group analysis". Then there is something that you are not doing correctly.

If after reviewing the configuration of your protocol, you still don't understand why this menu is available, please post screen captures of:

  • the database explorer in "anatomy view" showing the files withing the subject anatomy and the default anatomy
  • the database explorer in "functional view" showing the group grid and the channel file of the folder where you are trying to compute the volume head model.
  • a 3D view showing the grid of points that you want to use for this volume head model
4

Thank you for your response!
If I am using default anatomy for all subjects, will this option be not applicable?

5

In this case, if you simply compute the volume sources for each subject, you should obtain the same grid for all the subjects, and you should be able to average the files together. Isn't it the case?
No need to project a grid defined on a template to different subject spaces.

6

Yes, this is the case. Thank you so much.