[Freesurfer] Help with subject's functional overlay

Hello freesurfer experts,

The functional overlay for one of our subjects looks like the image attached. You'll notice the "holes" on the overlay that have a value of 0. I'm trying to get ride of these as I expect (as with other subjects) to have values for these vertices that are not 0. Myself and a colleague have tried improving the registration as much as we see possible, but the problem remains. Any tips on how to correct this issue would be greatly appreciated.

Thanks in advance for your help! Cesar Echavarria Research Assistant Martinos Center for Biomedical Imaging, Harvard-MGH Brain & Cognitive Sciences | MIT 2012