What do you mean with "the atlas can be transformed to the subject space"? What properties are you interested in? How are you planning to do your source analysis?
If you are only interested in specific ROIs that you know how to define for each of your subject, indeed you don't need to have the full source maps available in the template space.
The steps I am planning are:
1.import BISD
2.generate FEM mesh
3.compute tensor for FEM
4.align EEG positions and compute head model
5.running beamformer to reconstruct the source for specific frequency bands
6.extract time series for volumes based on atlas
7.I would use the extracted time series to perform some other statistical analysis e.g granger causality or other approaches.
In general, I am planning to reconstruct the source space and then extract time series from specific volumes (e.g after source reconstruction, I use AAL atlas to extract time series from the motor cortex).
Since subjects in their subject space after the inverse solution is different from template space(correct me if I am wrong), I was thinking about how I can extract the volume per subject, the solution to me seems to create the group grid so that I can compute the head model in line with the template. Later on, I saw the tutorial in section Volume_atlases, it says Volumes in MNI space can be imported and transformed to the subject space.. Does that mean I can just import atlas(MNI space) then it would be warp to my subject space? In this way, I do not need to create a group grid for my head model computation, right?
Thank you very much for your time and attention.