Plotting individual source stat data

[Robert Oostenveld]

Hi Christine

On 12 Jan 2009, at 17:29, Christine Gruetzner wrote:
> I'm trying to plot source stat data from individual subjects on the
> respective mri (according to the procedure suggested in the
> beamformer tutorial), but there seems to be a problem when I use
> sourceinterpolate (see below).
>
> Does anybody have an idea what's going wrong here?
> ...
> the input is source data with 4560 positions
> the input is volume data with dimensions [256 256 256]
> not downsampling anatomy
> not downsampling inside
> selecting subvolume of 0.0%
> interpolating
> ??? Attempted to access sel(1); index out of bounds because
> numel(sel)=0.

To speed up the interpolation of the functional onto the anatomical
data, the function determines the subvolume of the anatomical mri that
is spanned by the functional data. Usually the anatomical mri covers
the whole head (including chin and quite some air around the head),
whereas the functional data only spans the brain. The functional data
therefore takes only approximately 1/4 th of the volume of the
anatomical mri.

In your case it selects a subvolume of 0%, where I would expect a
subvolume of 25%. That means that the functional data completely lies
outside the space that is spanned by the anatomical MRI. Think of both
volumes as a wireframe cube: normally the functional "cube" would be
completely inside the anatomical "cube", but in this case it is
completely outside.

I suspect this to be due to a misspecification of the units (cm v.s.
mm) of either functional or anatomical data. You should check your
cfg.mriunits and cfg.sourceunits, or alternatively please read on:

I have recentently been working on the autodetection of the units,
which makes the manual specification unnecessary. The attached version
of sourceinterpolate (not yet part of standard fieldtrip) should
automatically detect the correct units (cm or mm) for the anatomical
and functional data. Could you please try ot the attached version?
Please rename your exsisting sourceinterpolate.m into
sourceinterpolate_orig.m and then copy this function into your
fieldtrip directory. I hope it solves your problem.

best regards,
Robert


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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 http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.