> I'm very confused by this... I thought SPM results were in MNI space.
> As far as I understand the various templates, from e.g.
> http://imaging.mrc-cbu.cam.ac.uk/imaging/MniTalairach
> SPM's templates are in the space of MNI305 and ICBM152. Can you give any
> more information/references about the shift you discuss?
> Thanks,
> Ged.
Dear Ged,
Don't worry about spm: the templates are indeed in MNI space. However, as I
understand it the Anatomy Toolbox works with an adapted MNI space, which
they name "anatomical MNI space" (see below for the passage where they
explain that, in Eickhoff et al. NIMG 2005). That was meant to keep the AC
at [0 0 0], which is not the case in he "original" MNI space. It does mean,
however, that the very nice skull-stripped template (colin27) they use is
also is this "anatomical" MNI space. That does not fit with the "original"
MNI space as employed by SPM...
Greetings, Rick
Eickhoff et al. NIMG 2005:
"The probabilistic maps are located in the space of the T1 weighted MNI
single subject template (Collins et al., 1994, Evans et al., 1992 and
Holmes et al., 1998). The origin of the MNI space is located 4 mm more
caudally (y axis) and 5 mm more dorsally (z axis) than the intersection
between the AC and the interhemispheric fissure in this specific brain. To
keep the AC as the anatomical reference of the coordinate system, the
origin of the probabilistic maps was corrected for this displacement. The
correction results in the so called “anatomical MNI space,” which differs
from the original MNI space by an affine translation along the y and z axes
of 4 and 5 mm, respectively. When using these maps for structure–function
analysis, the user is prompted, whether the functional data have been
normalized to the templates in standard MNI space as provided by SPM2 or
the corresponding templates in anatomical MNI space as used by the SPM
Anatomy toolbox. If the functional data have been normalized into the
standard MNI space, the SPM Anatomy toolbox automatically applies the
linear correction to the anatomical MNI space. All locations are then
reported both in standard and anatomical MNI coordinates."
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