Thanks John for the swift reply.
I was wondering, if I don't smooth the EPIs during Normalise to MNI and
then do the analysis (i.e. the preferred way of doing Bayesian inference
at the first level), can I smooth the computed contrasts using the
DARTEL way? Is there a smooth using DARTEL only option without
normalisation?
Regards,
Glad
On 04.06.2014 15:25, John Ashburner wrote:
> Yes there is, which is why I combined smoothing with warping. The
> slides at http://www.fil.ion.ucl.ac.uk/~john/misc/VBQ.pptx may help to
> explain the difference.
>
> Briefly, smoothing involves computing local weighting averages. In
> Dartel, the weighted averages involves summing up the voxel intensities
> (weighted by the smoothing kernel) and dividing by the number of voxels
> (weighted by the kernel). The other way of doing it (warping followed
> by spatial smoothing) essentially computes something different from this.
>
> Best regards,
> -John
>
>
>
> On 4 June 2014 14:01, Paul Glad Mihai <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>
> Dear SPM List,
>
> Is there a difference in the smoothing algorithm of DARTEL vs. the
> typical spatial smoothing?
>
> Regards,
> Glad
> --
> Glad MIHAI, M.Sc. Biomedical Physics
> Functional Imaging | University Clinic Greifswald
> Walther-Rathenau-Straße 46 | 17475 Greifswald | Germany
> Tel: +49 3834 86 69 44 <tel:%2B49%203834%2086%2069%2044> | Fax: +49
> 3834 86 68 98 <tel:%2B49%203834%2086%2068%2098>
> www.baltic-imaging-center.de <http://www.baltic-imaging-center.de>
>
>
--
Glad MIHAI, M.Sc. Biomedical Physics
Functional Imaging | University Clinic Greifswald
Walther-Rathenau-Straße 46 | 17475 Greifswald | Germany
Tel: +49 3834 86 69 44 | Fax: +49 3834 86 68 98
www.baltic-imaging-center.de
|