Dear John and SPM experts,
We are new to use VBM (SPM5) and trying to find the gray matter
differences in psychopaths compared to normals. We have a relatively
small sample size (9 versus 16) and smoothed the segmented images using
12 FWHM, and even though some differences were at regions we expected
(frontal areas), but a lot of the clusters were outside the brain. If
we want to try use explicit mask to masking out the non-brain areas,
what would be the best image to use?
Also, even we selected the gray matter images, a lot of x, y, z
coordinations were map onto white matter (used Talairach Daemon for
finding corresponding anatomical region and the BA numbers), what might
be the reason for that?
I know quite a few people talked about this problem before but after
reading through the previous emails, We still don't know what's the
best way to solve this.
Any comment or suggestion would be more than appreciated.
Best,
yaling
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