I want to define several ROIs, but I want to restrict my own ROIs based on Talairach space. Exacly, I would like to define two ROIs within the Supplementary Motor Area, pre-SMA and SMA-proper.

What may I do?

1?. First, I may define a ROI based on Brodman areas (BA6). However, it is too big and my ROIs are located in the mesial surface of BA6 in both hemispheres. And, moreover, I wish to distinguish among hemispheres and likewise among ROIs within hemispheres and within ROIs in the same hemisphere.

2?. Second, I may define a ROI based on pre-active ROI, for instance, in a control subject who allow me to differentiate these four ROIs. But it is not accurate because of the activation within these ROIs are not limited to my target ROIs.

3?. But, maybe if I over activate these ROIs in my control subject I might draw my own ROIs based on voxes sizes x-y-z and Talairach coordinates (x-y-z). However, I donīt know whether there is a perfect correspondence among voxels size and Talairach coordinates. Because when you define a ROI after clicking on OPTIONS button you can see x-y-z Talairach coordinates in "ROI infos" square, next to "Slice" and "NrOfVoxels". These coordinates are supposedly the central Talairach coordenate among that cluster of voxels (minimum 8 voxels within a cluster).

So, if there is a correspondence between voxels (1x1x1)and Talairach coordinates, might I draw accurately my ROI manipulating the "Max cluster range" within "3D Volume Tools"-"Talairach"(because my ROIs are not smaller than 8 voxels cluster)?

And might these ROIs be applied to group analysis correctly?

I donīt know if it is possible or I am dreaming.

Or, how can I do it?

Could anyone help me?

I was wondering how one might create an voi file that contains "subject-specific" ROIs?

I see that one can "draw" their own ROIs for a given space.
However, because of individual sulcul variability I am interested in matching a particular ROI to a specific subject.

Any help is greatly appreciated

hope this helps