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It looks like you have the latest version. I'll try to take the time to have a closer look at my code to see if I can figure out the real cause. Best regards, -John On 9 May 2012 17:27, shahrzad kharabian <[log in to unmask]> wrote: > Thanks a lot. > > I am using "Version 4290 (SPM8) 04-Apr-11" and I have exported "affine > transformed" GM and WM from VBM8 toolbox "estimate and write" to DARTEL > module (as it was suggested in VBM8 tutorial!). Could it cause the > mentioned instability?! > > Also, to Khader, the data is a mixture of healthy and non-healthy(in > different stages of disease), old women. I have not checked the white > matter lesions yet. So I have no idea about it and also subjects are rather > in the same age range. BTW, thanks a lot, these are good points that I > could look at them and search on them in future:) > > cheers, > Shahrzad > > > ------------------------------ > *From:* John Ashburner <[log in to unmask]> > *To:* [log in to unmask] > *Sent:* Wednesday, May 9, 2012 5:36 PM > *Subject:* Re: [SPM] Dartel template > > 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 > > >