Hello Rafael,
Ideally, you want the smoothing kernel to be not much larger than the smallest spatial effect you are looking for, while still improving signal-to-noise. Practically, you can use FSLview to check the results of smoothing - a good value is one that will appear to "soften" the image slightly without eroding detail. 1.5 times the voxel size is a common starting value.
Kind Regards
Matthew
> Dear all
>
> I have fMRI images of size 85 x 30 x 12 x 350 and voxel dimensions of 0.2mm x 0.2mm x 0.5mm. I have now applied a smoothing of 0.2mm.
>
> Is this too much or what value is recommended for smoothing here?
>
> All the best
>
> Rafael
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