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).
Isn't the non-isotropic smoothness related to the smoothness of the
statistical inference situation, i.e. the resels?
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