Dear SPM users
I am a little bit confused by the discussion about the "anatomical MNI
space"
(Eickhoff et al., 2005, NeuroImage) on the mailing list.
I agree with the observation that the origin of the MNI single subject brain
(Colin27) is not exactely on the AC. When correcting with the proposed
measures (-4 mm in y and -5 mm in z) there seems that the origin is now on
the AC.
But I got the same impression when had a look at the canonical templates and
apriors that were distributed with SPM5 (MNI_T1_152, MNI_T1_305,
ICBM_T1_452). The origin seems also to be 4 mm more caudally and 5 mm more
dorsally than the AC.
On the website http://www.sph.sc.edu/comd/rorden/anatomy/na_ac.html I found
the attached image showing that the MNI and ICBM origin is located not
exactely on the AC. Instead it is located at the right upper corner of the
AC
which in my opinion explains that displacement.
Therefore, there is no differences in the origins among these templates.
Otherwise a lot of published activations (labled with AAL or superimposed on
the single subject brain) would be mislocated by 4 and 5 mm, respectively.
When one corrects the single subject brain's origin with the proposed
mesures and do a segmentation with SPM5 or with the VBM5 toolbox, the
resulted segments showed the old origin again.
The last miracle in that story is that in order to move the origin down (z
direction) one has to type positive values (intuitively I expected -5 to
shift the origin down and +5 to shift them up).
Thanks a lot for clarification in advance
Best regards and merry Christmas
Juergen
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Juergen Haenggi, Ph.D. student
Psychiatric University Hospital
Division of Psychiatry Research
University of Zurich, Switzerland
PO Box 1931
Lenggstrasse 31, 8032 Zurich
0041 44 384 26 10 (office phone)
0041 76 445 86 84 (mobile phone)
0041 44 384 26 86 (fax)
H 115 (office room number)
[log in to unmask] (division email)
http://www.dpr.unizh.ch/ (division website)
http://www.juergenhaenggi.ch (private website)
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