Hi wangzhiwei, I'm a little confused by the question. There mention of area size and scales hints that there might be a confusion between tools used for quantification / significance testing and those used for display purposes.
Freesurfer has its own tools for significance testing, so you could use those. We often use threshold-free cluster enhancement for that purpose, which finds the significance threshold. Suprathreshold area can be computed once this threshold has been determined. But usually when I make a figure, I generate border around the suprathreshold regions and display these bordersover the "real" t- or f-map, using a scale that corresponds to my alpha (e.g., .05) divided by two (since I usually do both right and left hem tests). I compute this t or f-stat using my n / degrees of freedom. So the significance testing and display steps are separate, the way I do it. Now you might not be going as far as significance testing. Sometimes you just want to look at some preliminary data -- particularly for a single subject. A good start might be to understand if this is a single subject, group results, what kind of statistic. And certainly not everyone does this the way I do, so it would be helpful for others to weigh in with their viewpoints/conventions. Donna On Oct 28, 2014, at 9:53 PM, wangzhiwei3233 <wangzhiwei3...@126.com> wrote: > Hi, experts, > I converted fMRI results derived from freesurfer to caret, and not I want to > count activation areas on caret. So there is a problem of threshold and scale. > > Auto scale range is 0~60. I found that the area size was different when using > scale 1.3~4 from when using scale 1.3~60. And the latter one was smaller. > However , in the latter case(1.3~60), the value of a point that was next to > the border of activation area but in non-activation area was a little bit > lager than the threshold 1.3. > > How to set the scale to guarantee the activation accurate? > > Best! > > > _______________________________________________ > caret-users mailing list > caret-users@brainvis.wustl.edu > http://brainvis.wustl.edu/mailman/listinfo/caret-users _______________________________________________ caret-users mailing list caret-users@brainvis.wustl.edu http://brainvis.wustl.edu/mailman/listinfo/caret-users
