interpolated source activity values = NaN

[Frederic Roux]

Hi Ingrid,

thanks for the quick reply. I will try your suggestion but I am pretty much sure that the values I want to look at are inside the brain.

My approach is the following:

I want to indentify the voxels that show significant activation.
So first I visualized my data with sourceplot and cfg.interactive = 'yes' and then I write down the indices of the voxels onto which I click.

When I feed these indices into 
SourceInterpolatedStats.stat([x y z]) this returns me NaNs, even tough the voxel was clearly located inside the brain.

Do you have any idea of why this happens?

Frederic

Date: Fri, 4 Dec 2009 13:21:17 +0100
From: ingrid.nieuwenhuis at FCDONDERS.RU.NL
Subject: Re: [FIELDTRIP] interpolated source activity values = NaN
To: FIELDTRIP at NIC.SURFNET.NL






















Hi Frederic,

 

Probably the NaN’s are the voxels
outside the brain. The source estimate is only performed for voxels inside the
brain, the voxels outside are put to NaN. In
the field “inside” it is coded which voxels lay inside the brain.
Try:

SourceInterpolatedStats.stat(SourceInterpolatedStats.inside)

This should give you the non-NaN values.

 

Hope this helps,

Ingrid

 

 









From: FieldTrip
discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf Of Frederic Roux

Sent: Friday, December 04, 2009
12:51 PM

To: FIELDTRIP at NIC.SURFNET.NL

Subject: [FIELDTRIP] interpolated
source activity values = NaN



 

Hi everyone,



I would like to use the values that correspond to the interpolated statistics
at source level. 

The problem is that most of these values are NaNs, even tough I can visualize
them with sourceplot.



Here are the steps I am doing to compute these values:



[signal1] = sourcegrandaverage(cfg,data);

[signal2] = sourcegrandaverage(cfg,data);



[Stats] = sourcestatistics(cfg,signal1,signal2);%the statistics used here is
depsamplesT using fdr and clusterstatistics = maxsum

[SourceInterpolatedSats] = sourceinterpolate(cfg,Stats,template_mri);



This yields:



SourceInterpolatedSats =



       inside: [91x109x91 logical]

         stat: [91x109x91 double]

          dim: [91 109 91]

    transform: [4x4 double]

      anatomy: [91x109x91 double]

          cfg: [1x1 struct]



But when I try :



SourceInterpolatedStats.stat([20 45 68]) = NaN.

And this holds true for almost any index.



Does anyone know if it's possible to access these values?



Frederic







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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.

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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/neuroimaging/fieldtrip.
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