Dear andreas,
1) If you coregister your structural to your functional image then I think that
it is inevitable that the voxel size of the coregistered structural image will
be the same as the functional image. I can think of two possible ways around the
problem, both assume that you have normalized your individual subjects'
functional data:
i) Coregister the structural image to the (mean) functional image but coregister
only (do not reslice- which produces an r* image). Then you normalize the
structural image using the *sn3d.mat file generated from normalizing your mean
functional image to the (presumably) EPI template. The structural image is
resliced once only, giving a n*structural image rather than an nr*structural
image. As you have not resliced the structural image, I believe that it should
have the resolution of the MNI template (2x2x2mm).
ii) Another option would be to not coregister the structural image to the mean
functional image, but to normalize it separately to the (presumably) T1
template. If both normalizations work well, then both you functional and your
structural data will be in MNI space.
I hope that others will comment, especially if I have misled you here.
2) Where are the parameters for motion correction saved?
In a file called realignment_params_*txt, named after the first scan in the
realignment process. It should be saved in your working directory. It should
have six columns, with a number in each referring to the translations in x, y
and z and then the rotations in x, y and z.
I'll leave 3) to those who know more.
Cheers.
Alex.
1. When I coregistrate our high-resolution anatomical data to the
functional images, the realigned anatomicals are written with the
resolution of the functionals. Is this inevitable? Can the resolution of
the anatomical images be preserved within the realignment to the
functional? How do I do this? I have not found the opportunity at the
defaults bottom, so maybe it would need some editing in the code. I
guess, another option would be to write the functionals with a higher
resolution but I have no clue how to do this before normalization and I
donīt know whether this is accurate or may inflate the statistics.
2. Where are the parameters for motion correction saved? (I want to
enter them into the design matrix but have forgotten where SPM writes
them to. Sorry for asking that question redundantly!)
3. For a fixed group effects analysis, I would like to enter the single
sessions of the individual subjects into the design matrix together with
an ordinally scaled factor (regressor) of 3 different values. Is this
accurate? How can I specify the regressor and can I do F-testing on a
ordinally scaled factor taking up 3 different values?
Many thanks in advance -
andreas
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