Hi Ron,
On Wed, 7 Sep 2005, Ron Cheng wrote:
> Hi, there,
> I use Feat for fMRI analysis. I have some questions.
> suppose the folder for all experimental data is ~/exp1/, the fMRI data file is
> a.{hdr,img} with voxel resolution 3.3*3.3*3mm
> (1)After running feat preprocessing, i find a file filtered_func_data.nii.gz
> in ~/exp1/a.feat. I'm wondering whetehr this is the file after temporal
> filtering, and before registration (normalize to MNI space).
Yes, that's right - see
http://www.fmrib.ox.ac.uk/fsl/feat5/detail.html#prestats
and
http://www.fmrib.ox.ac.uk/fsl/feat5/detail.html#reg
> (2) I check the file filtered_func_data.nii.gz. Its voxel resolution is same
> as the orginal fMRI file, and different from MNI template image. It seems
> feat filter the data before normalization. In SPM, you first realign,
> normalize, and smooth the original image data, then model the preprocessed
> data as a time series; and use AR(1) to adjust data. My question is which
> method is better?
Theoretically, there's not much difference - our approach saves some disk
space, but apart from that it's not a big deal.
Cheers.
--
Stephen M. Smith DPhil
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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