Dear Rick,


I hope you don't mind me copying the reply to the SPM mailing list as I guess other users might have the same question.

The maximum and minimum coordinates given by the function "Visualisation and statistics of cytoarchitectonic probabilistic maps" and shown in the NeuroImage papers define the bounding box of the displayed cytoarchitectonic probability map. That is, the maximum and minimum coordinates, such that the x-coordinates of all voxels where this area was observed fall between Xmax and Xmin, their y-coordinates between Ymax and Ymin and their z-coordinates between Zmax and Zmin. Or, in other words, the respective area has never been observed outside these coordinates.

However, there is no need, for the voxel corresponding to [Xmin, Ymin, Zmin] to actually belong to the probability map as well, or even to fall inside the reference brain. You should, however, see at least one voxel of the respective map in each of the three orthogonal sections, if you centre the crosshairs on [Xmin, Ymin, Zmin].



The second set of coordinates provided (50% min/max), define a second, tighter bounding box, representing the most extreme coordinates inside which voxels with a probability for the respective area of 50% or above can be encountered.


Do they have any use for you? As you would usually compare coordinates, e.g. from other papers, using the "Cytoarchitectonic probabilities at defined MNI coordinates"-function, the main purpose of the descriptive statistics you refer to is, to provide an impression of the size, location and variability or individual cytoarchitectonically defined areas in a more interactive and complete fashion as possible by the two or three sections shown in the respective publications. Having a better feeling for the anatomical data, may then help you interpreting the correspondence between structure and function calculated by the SPM Anatomy Toolbox.



Hope this helps
Simon

> -----Ursprüngliche Nachricht-----
> Von: Rick Helmich <[log in to unmask]>
> Gesendet: 14.12.06 12:45:42
> An: [log in to unmask]
> Betreff: anatomy toolbox


>
>
> Dear Dr. Eickhoff,
>
>
>
>
>
> I have a question about your anatomy toolbox that I hope you
> have time to answer. I already read your Neuroimage papers (2005; 2006) and the
> manual, but one thing still doesn’t make sense to me.
>
>
>
>
>
> In the probabilistic maps of individual regions (e.g. Fig. 2
> in NIMG 2005; area 3b), the centre of gravity is given, as well as the maximum
> and minimum stereotactic coordinates based on two calculations. Could you
> explain to me what those maximum and minimum coordinates represent? When moving
> to those locations, I end up far away from the probabilistic area or even
> outside of the brain (when taking colin27 as the template for my probabilistic
> map). How are these coordinates calculated, and how should I interpret them? Do
> they have any use for me?
>
>
>
>
>
> For your information, I am using the new updated version 1.4
> that I download from your website yesterday.
>
>
>
>
>
> I am curious after your answer, many thanks in advance!
>
>
>
>
>
> Yours sincerely,
>
>
>
>
>
> Rick Helmich
>
>
>
>
>
> --------------------------------------------------------------------------
>
>
> Rick C.G. Helmich, MD (Ph.D student)
>
>
>
>
>
> F.C. Donders Centre for Cognitive Neuroimaging
> P.O. Box 9101
>
> 6500 HB Nijmegen
> The Netherlands
>
>
>
>
>
> T 00 31 (0)24 36
> 65077
> F 00 31 (0)24 36 10989
> E [log in to unmask]
>
>
> web: www.fcdonders.ru.nl
> --------------------------------------------------------------------------
>
>
>
>

--


===================================
Simon B. Eickhoff
Institut für Neurowissenschaften und Biophysik - Medizin
Forschungszentrum Juelich
Leo-Brandt-Str. 5
52425 Juelich
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eMail: [log in to unmask]
Telefon: +49 2461 61 8609
Fax: +49 2461 61 2820
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