Hi,

It appears that the rest.nii files in the Dallas data set are left-right flipped.

I noticed this for two subjects I examined so I assume it's true for all of them.

Now, I could be wrong (left-right issues are tricky), of course. But if you look at sub16493 slice 141 for mprage_skullstripped and 21 for the rest.nii file, examine the posterior horn of the lateral ventricles, where the asymmetry is reversed for the two images. I believe the mprage is correctly oriented (RPI) and the functional image is actually LPI.

also, I flipped the rest image (and then manually resetted the orientation in the header) and reran "align_epi_anat.py" and got much better registration.

Brad Buchsbaum