> I have prepared my own customized template using
> SPM99, now using the simple VBM protocol I want to
> smooth the images to prepare the customized gray and
> white matter template.
>
> The question is, is it ok to use 8mm FWHM instead of
> 12 mm because we have some small structures to be
> taken into consideration. I read in the emailing list
> sometime back that it should be atleast 2-3 times
> bigger than the voxel size. I have 1.5,1.5,1.5 voxel
> size image!
Templates should be smoothed by 8mm, if you use the default
settings. Images included in a VBM analysis are usually
smoothed by about 12mm, but they could be made less smooth.
Check how well registered these structures are after spatial
normalisation. The amount of smoothing that should be used
is partially related to the accuracy of the registration.
Best regards,
-John
--
Dr John Ashburner.
Functional Imaging Lab., 12 Queen Square, London WC1N 3BG, UK.
tel: +44 (0)20 78337491 or +44 (0)20 78373611 x4381
fax: +44 (0)20 78131420 http://www.fil.ion.ucl.ac.uk/~john
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