Hi, I've just started using the newest freesurfer v 5.3 and I've noticed in the labels folder that every .label has a thresh.label. When overlaying the two, they can be quite different (for example MT.label is much larger than MT.thresh.label) or quite similar (V1.label is just a tiny bit larger than V1.thresh.label). What is the difference between the two and which is best to use?