Hello Helmut,
> thanks for pointing to the Rohlfing and Tahmasebi papers, I didn't
> know about them. Well, it seems there is no easy solution then. My
> subjects are aged 16 to 17, so I would have been interested in
> differences between age-specific TPMs and standard TPMs plus
> differences related to spatial smoothness of the TPMs. However, I'm
> not after evaluating different algorithms, at least at the moment.
> Rather I want to analyse some fMRI data, and I would have liked to
> "prove" why it was a good idea to go with some specific TPMs during
> preprocessing. I guess I'll use the default parameters / 6 TPMs in
> SPM12 then ;-)
I think the principle problem you run into here is that you do not know
what is "right", so it is hard to compare results against a gold
standard. One way to address it is to say, if the error increases with
younger children, then it is probably systematic, but that likely is not
an approach you can or want to take.
From a theoretical point of view, though, there are strong arguments in
favor of using age-appropriate priors, the more so the further you are
away from the population contributing to the standard priors (which is
why I keep reiterating here that I believe this problem to be at least
as big for most research done in elderly subjects).
Cheers,
Marko
PS: And yes, the priors coming out of TOM are somewhat blurry; this is
because we opted to do an affine-only registration, for what I still
feel are defensible reasons. You could of course do it differently if
you reprocess the dataset and use TOM on these results.
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
[log in to unmask]
http://www.medizin.uni-tuebingen.de/kinder/epn/
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