Hi Sofia, Let's say you have an activation map (fMRI) in volumetric form for your subject, for whom you also have a fiducial surface. Provided that the fMRI has been volume-registered to the same anatomical used to generate the fiducial surface.
When you map that fMRI volume onto the surface, you always map to the fiducial surface. (Note that the fiducial surface might be a white matter, pial, or midthickness representation. If the surface was generated using Caret, it's a midthickness surface. If it was generated using, say, Freesurfer, then a midthickness surface is easily generated by averaging the WM and pial surfaces.) Once the fMRI is mapped onto the fiducial surface, then you have a node-scalar mapping that can be rendered/overlaid on any surface configuration (flat, inflated, etc.). But one never maps to the inflated/flat surfaces directly. It's worth mentioning that the Caret surface, being a midthickness surface, won't necessarily intersect your white matter voxel. It depends on the fMRI resolution and how the fiducial surface intersects the fMRI volume there. There are various mapping algorithms that help you get around this problem (gaussian being the most helpful, probably). But if you have an actual white matter surface available, it is possible to map to that, as well. If the voxel is deep in the white matter, it will still not intersect the WM surface, but then it is of questionable validity, I would think. Hope this helps, Donna On 05/14/2009 04:45 AM, s.cres...@campus.unimib.it wrote: > dear Donna > I have a we question concerning the overlapping metrical data on the flat map. > If I have some voxel belonging to the white matter how does caret manage them > with respect to the flat? > > thank you! > sofia > _______________________________________________ > 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
