Hi Kirstie there is no easy answer to this question, but there are some guidelines:
1. The size of the smoothing kernel depends on the size of the effect you are looking for and how well you expect it to align across subjects. For example, you would need a far smaller smoothing kernel if you expected to find a small change in the middle of the calcarine than if it was in more variable frontal or parietal regions. 2. The more subjects you have in your study the less smoothing you probably need. 3. You pay a far smaller price for large kernels on the surface than you do in the volume. Sorry I don't have a more useful answer. Doug might have more to add (but note our responses may be slower than usual as we are putting on a course in Boston this week) cheers Bruce On Mon, 27 Oct 2014, Kirstie Whitaker wrote: > Hi everyone, > > Firstly - thank you for the excellent tools. This year has been my first > foray into surfaced based analysis and I'm enjoying it very much. > > I don't currently have a gut instinct for an appropriate level of surface > smoothing. I'm sure that can't be easily answered but would a range of, say, > 3 to 5mm sound good? Or more like 10 to 15mm? > > Currently I'm considering cortical thickness analyses, but I may extend into > functional analyses in the future. > > If there are any references that you can recommend I'd appreciate that very > much. > > Best wishes > Kirstie > > -- > Kirstie Whitaker, PhD > Research Associate > > Department of Psychiatry > University of Cambridge > > Mailing Address > Brain Mapping Unit > Department of Psychiatry > Sir William Hardy Building > Downing Street > Cambridge CB2 3EB > > Phone: +44 7583 535 307 > Website: www.kirstiewhitaker.com > > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
