On Fri, 12 Feb 2010 17:15:36 +0000, John Ashburner wrote:
>Realign, Coreg, Normalise and the old Segment are pretty much the same
>as in SPM5. However, SPM8 has a new version of the segmentation (see my
>email from a few minutes ago) that I think will achieve more accurate
>spatial normalisation than the older versions.
Given the improvements you listed in the other post, does this dramatically
change the structure of the output files? I only ask because my system (1GB
physical + 3GB virtual memory in 32 bit XP) reports "out of memory" when I try
to import certain new segmented images - specifically 150ish megabyte
MPRAGE files - into DARTEL. The new segmented images (i.e. c1 to c5) were
produced and can be viewed but this "out of memory" seemed to pop up when
the program tries to produce the DARTEL files (i.e. rc1 etc.).
I should note that the old segmented files of these MPRAGE images were
processed through DARTEL without trouble and the 50ish megabyte SPGR files,
which were segmented using the new method, could also be successfully
imported into DARTEL.
>Dartel is a still more accurate approach to spatial normalisation,
>although it is a bit more complicated to use.
I've been following this modulated vs. unmodulated debate here on the mailing
list. I understand that Dr. Ashburner's position is that an unmodulated
comparison merely reflects registration error but others such as Mechelli 2005
and Gaser etc. suggest that unmodulated analyses reveal brain matter
density/concentration. Now, with the improvement of registration through the
use of new segmentation and DARTEL, does this change the debate in any
way? If not, I'm sorry for beating a dead horse. Of course, I am assuming we
are not studying subjects with significant deformation or volume reduction
which would interfere with registration.
Thank you for your attention.
Sincerely,
Dennis
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