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For clarification....

Isotropic smoothness is the state of equal x-, y- and z-FWHM smoothness.
Non-isotropic smoothness is never a problem (SPM has never assumed isotropic
smoothness).

Non-stationary smoothness is spatially varying FWHM smoothness.  SPM's
cluster size inference assumes stationary smoothness; dealing with
nonstationarity requires the NS toolbox (directly or via the VBM toolbox).

-Tom

On Thu, Jun 19, 2008 at 1:57 PM, Simone Reinders <[log in to unmask]>
wrote:

> Hi Austin,
>
> Isn't the non-isotropic smoothness related to the smoothness of the
> statistical inference situation, i.e. the resels?
>
>
> http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0802&L=SPM&P=R39928&D=0&I=-3&m=24842
>
> Regards,
> Simone.
>
> On Mon, Jun 9, 2008 at 10:04 PM, Austin Woolard
> <[log in to unmask]> wrote:
> > Is it necessary to correct for non-isotropic smoothness when one has
> > isotropic voxel sizes during the first-level analysis in SPM5?
> >
> > Any relevant information would be very helpful.  Thanks!
> >
>
>
>
> --
> Dr. A.A.T. Simone Reinders, MSc PhD
> King's College London
> Institute of Psychiatry (IoP)
> Box P063, De Crespigny Park
> London SE5 8AF
> United Kingdom
>
>


-- 
____________________________________________
Thomas Nichols, PhD
Director, Modelling & Genetics
GlaxoSmithKline Clinical Imaging Centre

Senior Research Fellow
Oxford University FMRIB Centre