As Satra pointed out, the final template seems to be OK. I therefore
think your overall alignment should be fine.
Which version of SPM8 did you use (and did you use more than the usual
GM and WM tissues)? The problem is the result of an instability in
the way the template is smoothed, which I have occasionally seen. As
far as I was aware though, I thought I'd fixed it in the more recent
SPM8 updates.
The smoothing is not the usual sort of smoothing that involves
convolving with a Gaussian. Instead, the idea was to smooth by
including a regularisation model in the generation of the template,
which regularises more heavily in the earlier iterations and less in
the later ones. Computations are only done with single precision
floating point, so it is a bit more difficult to ensure the various
computations are 100% stable (while still reasonably fast)
Best
regards,
-John
On 9 May 2012 16:08, shahrzad kharabian <
[log in to unmask]> wrote:
> Dear SPM experts,
>
> I have made a DARTEL template of about 68 brains of old subjects and I got
> the attached templates. It seems for me that the first 2 templates _0 and _1
> are rather strange. I need your help to know how should I deal with it, what
> the reason for this could be and if it might affect my further analysis (as
> the last template seems reasonably good to me).
>
> Bests,
> Shahrzad
