I am using Freesurfer 6.0 and the latest (freeview  -beta) to display overlays on my flat surfaces.

I am a novice user of freesurfer and I am a bit confused with how the overlays are displayed / thresholds calculated.

My overlay of rsquare values ranges from 0.2 to 1.0 (i.e all are positive values.). When the overlay is loaded, the threshold histogram depicts values that are negative and positive (centered around zero).

1) Does freeview recaluate/modify the values before they are displayed?

2) Is it possible to display the values of the overlay as they are?