I agree with everything that has been said on this topic, but I'd like to plead with all authors of papers to state which "Talairach"
system is used in a paper. If they are MNI space coordinates, it should say so. If they are simple bicommissural coordinates based on
identification of the AC and PC, it should say so. If there is a scaling or transform involved (such as Matthew's) it would be nice to
know.
All the best,
Krish
Russ Poldrack wrote:
> I'm not sure if this is a discussion that's already been had on the list, but I worry about using the MNI-Talairach conversion.
> In particular, what's the logic for computing the converted coordinates? There are several possible reasons that I could imagine
> doing this, and I think that in each case there are arguments against it.
>
> 1. to use the Talairach atlas to determine brodmann's areas. the folly of this has been discussed many times on the list.
>
> 2. to use the talairach atlas to determine the anatomical location of an activation. This also seems to me to be a bad idea,
> since we almost always have the subject's anatomy and can look at it to directly figure out where we are (using a high-resolution
> atlas like Duvernoy or Mai et al. to determine what is what if necessary).
>
> 3. To calculate numbers to put into a foci listing in a paper. It's not clear to me why this is a good idea either. Although
> the talairach space has been the standard, it seems that just as many people now are using the MNI space. In addition, so far as
> I know Matthew's conversion algorithm has not been fully explored or validated (this would be difficult since we don't have
> imaging on the subject from the Talairach atlas). All the more reason to stick with a space that has been well-described and has
> good templates (the MNI305).
>
> If there are other reasons to do the transform that overcome these objections I hope that someone will point them out. Given all
> the problems with the original Talairach space it seems that we should just embrace the MNI space - if someone down the line
> wants to put the data into Talairach space (e.g., for a meta-analysis), then they can use the transformation at that point without
> any loss of fidelity in the original data.
>
> cheers,
> russ
>
> Barbara Tillmann wrote:
>
> > --- You wrote:
> > We have the problem that the Talairach coordinates in SPM do not equal the
> > Talairach coordinates in the Talairach-Tournaux Atlas. Maybe someone could
> > explain us this.
> > Moreover, we are looking for a tool to solve this problem, respectively for
> > a software able to perform this recalculation/ conversion.
> > --- end of quote ---
> >
> > Matthew Brett provides a discussion on the difference between the MNI brain (used by SPM) and the brain in the Talairach atlas:
> >
> > http://www.mrc-cbu.cam.ac.uk/Imaging/mnispace.html
> >
> > This page also includes a possible transform, and further information can be found at:
> >
> > http://www.mrc-cbu.cam.ac.uk/personal/matthew.brett/MNITal/mnital.html
> >
> > Barbara.
> >
> > Barbara Tillmann
> > Dartmouth College
> > Department of Psychological and Brain Sciences
> > 6207 Moore Hall
> > Hanover, NH 03755
> > USA
> > Tel +1.603.646.0062
> > Fax +1.603.646.1419
--
Dr Krish D Singh
Department of Vision Sciences
Aston University
Aston triangle
Birmingham
B4 7ET
ENGLAND
tel: +44 (0)121 359 3611 ext 5176/5190
fax: +44 (0)121-333 4220
email: [log in to unmask]
|