Hi Lauren,

It looks like you are getting closer. Few things:
1) In this last example, did you first generate the group template and then register that to the IIT atlas? Or did you register individual subjects to the atlas and then took their mean? I am trying to understand where the blurriness you mentioned comes from.
2) Although blurry, your group wise template looks like it matches the IIT space relatively well.
3) Have you tried other values for the regularization parameters?
4) Atrophy certainly reduces normalization accuracy. The magnitude of this effect depends on the amount and pattern of atrophy. I suggest you experiment with regularization a bit to find a good balance that works for your project.

Regards,
Konstantinos