Dear experts,

I was wondering if someone could please tell me what the mask.nii.gz in the .gica directory (after running multi-session temporal concatenation) is? I assumed that it's the average mask of all the participants' functional images, i.e., the result of fslmerge. But fslmerge (with -t option) outputs a 4D image whereas the mask in this directory is a one volume image. Is there a step that melodic does after fslmerge to turn the 4D into a 3D image or are these two separate images?

Thank you in advance

Helen