Hi Christophe,
thanks for the link, this is similar to the FDR cluscorr script that Tom
Nichols conceived and sent out a while ago which still seems popular :)
However, in the past I stumbled upon the issue that, when enabling
non-stationary smoothness correction, a smaller cluster may be
significant when a larger one may not be, due to differing local
smoothness estimates. If one wants to use that feature, I believe it is
necessary to not simply apply a global extent threshold, but rather to
loop over the individual clusters to see if they are in the list of
significant clusters provided by spm's results table. But it has been a
while since I looked into this.
Cheers,
Marko
Christophe Phillips wrote:
>
> Hi Luis, Marko et al.
>
> If you want to set your extent threshold such that it corresponds to
> some statistical threshold, i.e. a cluster-level corrected p-value, you
> may be interested in this small routine:
> https://github.com/CyclotronResearchCentre/SPM_ClusterSizeThreshold
>
> Cheers,
> Chris
>
> Christophe Phillips
> GIGA in silico medicine &
> Cyclotron Research Centre
> University of Liège, B30
> 4000 Liège, Belgium
> T: +3243662316
> F: +3243662946
>
> ------------------------------------------------------------------------
> *De: *"Marko Wilke" <[log in to unmask]>
> *À: *[log in to unmask]
> *Envoyé: *Mardi 12 Janvier 2016 08:03:17
> *Objet: *Re: [SPM] SPM 8 Extent threshold voxels
>
> Hi Luis,
>
> the extent threshold value specifies the minimum number of voxels a
> cluster has to meet in order to be displayed. If set to 0, all voxels
> meeting the voxel threshold criterion will be displayed (default). If
> you set it to, say, 10 in an fMRI study, cluster not reaching 10 voxels
> will be hidden. If you search for "cluster extent" and "cluster
> corrected" thresholds in the list archives at
> https://www.jiscmail.ac.uk/cgi-bin/webadmin?S1=spm , you will find some
> hints as to which values may be considered reasonable to some :)
>
> Cheers
> Marko
>
> Luis Casado Aranda wrote:
> > Hi everyone,
> >
> > I'm starting with the use of SPM and I have one question about the
> contrast step. What is the 'extent threshold voxels' and how to change
> the value of 0 in SPM8?
> >
> > Thank you very much in advance
> >
> >
>
> --
> ____________________________________________________
> PD Dr. med. Marko Wilke
> Facharzt für Kinder- und Jugendmedizin
> Leiter, Experimentelle Pädiatrische Neurobildgebung
> Universitäts-Kinderklinik
> Abt. III (Neuropädiatrie)
>
> Marko Wilke, MD, PhD
> Pediatrician
> Head, Experimental Pediatric Neuroimaging
> University Children's Hospital
> Dept. III (Pediatric Neurology)
>
> Hoppe-Seyler-Str. 1
> D - 72076 Tübingen, Germany
> Tel. +49 7071 29-83416
> Fax +49 7071 29-5473
> [log in to unmask]
>
> http://www.medizin.uni-tuebingen.de/kinder/epn/
> ____________________________________________________
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
[log in to unmask]
http://www.medizin.uni-tuebingen.de/kinder/epn/
____________________________________________________
|