Minimum norm analysis for timelock-data

[jan-mathijs schoffelen]

Computing MNE is apparently not something many people want to do with  
fieldtrip so it seems the implementation is still far from streamlined.

For the time being, you could try a hack, which transforms your output  
into one which fieldtrip may swallow.
I would suggest something like this:

nvox = size(source.pos,1);
mom = cell(1,nvox);
for k = 1:length(source.inside)
   indx = source.inside(k);
   mom{indx} = source.avg.pow(xx,:); %I don't know whether avg.pow  
contains only the inside voxels, so xx could be either indx, or k.
end
source.avg.mom = mom;
source.avg = rmfield(source.avg, 'pow');

I wonder whether it works after this...

Best,

JM

PS: I would actually opt for improving fieldtrip's implementation and  
handling with MNE-estimates. Perhaps we could do this together? We can  
do this offline (not through the discussion list). Would it be  
possible to post some fieldtrip data-structure, along with the  
necessary accessories (grids, vols etc), as well as your script?



On Jan 11, 2010, at 3:55 PM, Christine Gruetzner wrote:

> Dear Fieldtrippers,
>
> I still have this problem with performing source analysis (minimum  
> norm estimate) on timelockdata. As already mentioned, the main  
> problem occurs in sourcegrandaverage, probably because the output  
> data from source analysis (using cfg.method = 'mne' on timelock  
> data) contain an avg.pow field with the dimensions 4560x211 for each  
> subject, where 211 is the number of time samples.
>
> I have tried several things to avoid the problem with  
> sourcegrandaverage, but there are always new problems; for example,  
> when I put the source data directly into sourcestatistics, without  
> using sourcegrandaverage, there is a problem with checkdata, saying  
> that the function requires source or volume data as input. Computing  
> the timelockdata only for a single latency results in a problem in  
> source analysis ('error in minimumnormestimate at 143, mom = w*dat).
>
> Does anyone have a script for computing MNE on timelockdata that  
> works?! I would be very glad if someone could help me out with this  
> problem!
>
> Thanks and Best
> Christine
>
>
> -- 
> Christine Grützner, geb.Tillmann
> Max-Planck-Institut für Hirnforschung
> Abt. Neurophysiologie
> Deutschordenstr. 46
> 60528 Frankfurt am Main
> Germany
>
> Phone: +49 (0)69/6301-83225
> E-Mail: tillmann at mpih-frankfurt.mpg.de
> http://www.mpih-frankfurt.mpg.de/global/Np/Staff/tillmann.htm
>
>
> ----------------------------------
>
> 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.
>
> http://listserv.surfnet.nl/archives/fieldtrip.html
>
> http://www.ru.nl/fcdonders/fieldtrip/
>

Dr. J.M. (Jan-Mathijs) Schoffelen
Donders Institute for Brain, Cognition and Behaviour,
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands
J.Schoffelen at donders.ru.nl
Telephone: 0031-24-3668063


----------------------------------
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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