[FieldTrip] What exactly does 'minnbchan' refer just to spatial neighbors?

Eric Maris e.maris at donders.ru.nl
Tue Feb 8 17:01:46 CET 2011


Dear David,


> Thanks very much for the email Eric, but I'm confused as to why you
> answered "No" to my second comment.  From what I understand, if you
> use a value of minnbchan that is greater than 0, then any significant
> clusters will necessarily spread across multiple electrodes.  For
> example, if you set minnbchan to 1, then all significant clusters will
> have to include at least two electrodes so that each significant
> "voxel" has at least one neighbor at another electrode.  Thus, if your
> effect is truly at only a single electrode, having a value of
> minnbchan greater than 0 will force you to miss the effect or to think
> it occurs at more electrodes than it really does.  What part of my
> reasoning is incorrect?

Your reasoning is correct and mine was incorrect. I should read better
before I write. My apologies for this.

I do have to qualify that with minnbchan=0 it may also happen that your
significant cluster contains more than one electrode (the electrode with the
true effect plus some surrounding ones that by accident exceed the threshold
that is used to identify clusters).

Best,

Eric




>      again, thanks very much for the help,
>             -David
> 
> 
> > Best,
> >
> > Eric
> >
> >
> > dr. Eric Maris
> > Donders Institute for Brain, Cognition and Behavior
> > Radboud University
> > P.O. Box 9104
> > 6500 HE Nijmegen
> > The Netherlands
> > T:+31 24 3612651
> > Mobile: 06 39584581
> > F:+31 24 3616066
> > mailto:e.maris at donders.ru.nl
> > http://www.nphyscog.com/
> >
> >
> >
> >
> >
> >
> >
> >
> >>     thanks for your help,
> >>         -David
> >>
> >>
> >> --
> >> David Groppe, Ph.D.
> >> dgroppe at cogsci.ucsd.edu
> >> http://www.cogsci.ucsd.edu/~dgroppe/
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> 
> 
> 
> --
> David Groppe, Ph.D.
> Postdoctoral Researcher
> Kutaslab
> Dept. of Cognitive Science
> University of California, San Diego
> http://www.cogsci.ucsd.edu/~dgroppe/
> 
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