Problems with plotting sourcestatistics (partially) solved

Ingrid Nieuwenhuis ingrid.nieuwenhuis at FCDONDERS.RU.NL
Tue Oct 30 15:38:21 CET 2007


Dear Micheal,

You could try cfg.inwardshift = -1.5; when you do prepare_leadfield. This
makes that the "inside" field becomes larger (negative inside shift is
actually an outward shift). Plotting of the grid to see if everything went
okay is recommended. This should make the inside of the data coming out of
sourcegrandaverage also larger, since that function only uses the voxels
present in the inside of all subjects. It worked for me.

Good luck,
Ingrid


-----Original Message-----
From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf
Of Michael Wibral
Sent: Tuesday, October 30, 2007 2:11 PM
To: FIELDTRIP at NIC.SURFNET.NL
Subject: [FIELDTRIP] Problems with plotting sourcestatistics (partially)
solved

Dear Fieldtrippers,

a while ago I posted to this list about some problems with plotting
sourcestatistics for multiple subjects. That problem is solved by now,
fortunately - the plotting routine after sourcestatistics simply needed an
additional cfg.sourceunits='mm' although I do not get exactly where this
information got lost on the way. The other problem I have now is that,
despite (nonlinear) volume-normalisation the brains of my subjects do not
seem to share too many voxels, i.e. the ".inside" field of
sourcegrandaverage
is pretty small. Even if I fake perfectly matching subjects by feeding the
same subject 10 times the area used for the statistics is considerably
smaller than the brain in the template MRI.
Any idea what could be wrong? I made grid and hdm for the individual
subjects as described in the tutorial and used Guido Noltes hdm - is that
too spherical, possibly?? my result are especially "brain deficient" at the
occipital pole.

Thanks for your help,
Michael Wibral

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The aim of this list is to facilitate the discussion between users of the
FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG
and EEG analysis. See also
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http://www.ru.nl/fcdonders/fieldtrip.

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.



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