If you open the "Mesh morphing and coloring" dialog and click on "Options",
one of the options is named "Restrict selection area".
The standard value here is 150.
You can change this value and get accordingly smaller or larger minimal regions selected.
Please let me know if you have any other questions.

best regards

Armin

Thanks-
Jim Stefansic
Vanderbilt University[/B][/QUOTE]

After your nice answer, can I follow on to ask a related question?

When I click the activation in the flattened map, I can see the corresponding location in the axial-corronal-saggital slices. But I notice that the areas are the same, but the size are NOT! For example, the following pictures come from the same subject.

When I click the flattened image, I get the corresponding roi in her axial slice, with the roi size 170 voxels. But there are 326 voxels originally in that roi (according what's shown on the option-> voi info window).

Apparently some voxels are lost in the flattening process, but what cause those losses? Any comment or suggestion is welcome!

Thanks,
Chun-Chia

[This message has been edited by Chun-Chia_Kung (edited 22 October 2003).]

I'm not Armin, but let me give you a quick answer: When you select a ROI in the surface, the readout is restricted to a certain depth. I assume this is why the ROI sizes differ in your case.
You can try and play around with the readout:
Go to "Mesh morphing and coloring",
"Options" and select the readout depth in the "Functional data VTC access" part in the left upper corner.

I hope this answers your question!

Cheers,

Thanks for the previous suggestions, which are exactly where one can change the depth of the readVTC function (Meshes->Mesh morphing and coloring -> Options -> top left "Functional data VTC access"). But interesting, what really made me succesfully get the full ROI voxels is by checking the lower row of "Vertex > voxel > cluster access", instead of the upper "Surface patch > voxels access". Changing the starting or end "Read func depth" didn't help much. I did use the mask file in my data analysis. The only downside of being able to choose the whole ROI voxels in the flattened map is to lose the ability to highlight (by circumscribing the border of) the ROI.