[FieldTrip] NaNs as output of ft_sourceanalysis (DICS)

[Eelke Spaak]

Dear Andreas,

How many NaNs do you get exactly and in which field? If it is some
NaNs in source.avg.pow, then it is quite normal: the estimates for
dipole locations which were flagged as outside the brain are always
NaN, as they are not scanned. The following should hold:

sum(isnan(source.avg.pow)) == numel(source.outside)
&&
sum(~isnan(source.avg.pow)) == numel(source.inside)

Best,
Eelke

On 4 June 2013 11:42, Andreas Sauer <sauer.mpih at googlemail.com> wrote:
> Dear all,
>
> I would like to analyze sources with the beamforming approach using the DICS
> method. I followed the steps in the tutorial and everything works well.
> However, the output of ft_sourceanalysis contains only NaNs.
>
> I checked the TF data that I calculated in the step before but that looks
> fine, so I assume the error happens somewhere during ft_sourceanalysis.
>
> That's how I calculate the TFRs:
>
>         cfg = [];
>         cfg.toilim = [-0.5 -0.3]; % baseline activity
>         eval(['dataPre =
> ft_redefinetrial(cfg,Cond_',num2str(cond(j)),');']);
>         cfg.toilim = [0.1 1.0]; % task-related activity
>         eval(['dataPost =
> ft_redefinetrial(cfg,Cond_',num2str(cond(j)),');']);
>
>         % Combine the two datasets...
>         data = appenddata(cfg, dataPre, dataPost);
>         trialdesign = [ones(1,length(dataPost.trial))
> ones(1,length(dataPre.trial))*2];
>
>         % ... and compute the CSD matrices...
>         cfg = [];
>         cfg.output     = 'powandcsd';
>         cfg.channel    = Channel.meg;
>         cfg.method     = 'mtmfft';
>         cfg.taper      = 'dpss';
>         cfg.foilim     = [75 75];
>         cfg.tapsmofrq  = 15; % amount of spectral smoothing = +/- 15 Hz
>         cfg.channelcmb = {Channel.meg Channel.meg};
>
>         % ... for the baseline and task part separately...
>         eval(['freqPre.Cond_',num2str(cond(j)), ' =
> ft_freqanalysis(cfg,dataPre);']);
>         eval(['freqPost.Cond_',num2str(cond(j)), ' =
> ft_freqanalysis(cfg,dataPost);']);
>
>         % ... and for the whole trial
>         eval(['freqAll.Cond_',num2str(cond(j)), ' =
> ft_freqanalysis(cfg,data);']);
>         eval(['freqAll.Cond_',num2str(cond(j)), '.trialdesign =
> trialdesign;']); % pre and post info
>
> And that's how I calculate the sources:
>
>         cfg               = [];
>         cfg.frequency     = 75;
>         cfg.method        = 'dics';
>         cfg.grid          = grid; % Here it gives .pos, .inside, .outside to
> the structure
>         cfg.vol           = vol;
>         cfg.dim           = template_grid.dim; % Here I give the dimension
> of the template grid
>         cfg.grad          = Cond_101.hdr.grad;
>         cfg.lambda        = '5%';
>         cfg.reducerank    = 'no';
>         cfg.projectnoise  = 'yes';
>         cfg.realfilter    = 'yes';
>         cfg.keepfilter    = 'yes'; % the output saves the computed inverse
> filter
>
>         eval(['SourceAll = ft_sourceanalysis(cfg,
> freqAll.Cond_',num2str(cond(k)),');'])
>
>         % use the common filter here
>         cfg.grid.filter = SourceAll.avg.filter;
>         eval(['sourcePre_con = ft_sourceanalysis(cfg,
> freqPre.Cond_',num2str(cond(k)),');'])
>         eval(['sourcePost_con = ft_sourceanalysis(cfg,
> freqPost.Cond_',num2str(cond(k)),');'])
>
>
>
> I would really appreciate any help with that! Thanks a lot!
>
> Best,
>
> Andreas
>
> --
> Andreas Sauer
> Max Planck Institute for Brain Research
> Deutschordenstr. 46
> 60528 Frankfurt am Main
> Germany
>
> T: +49 69 96769 278
> F: +49 69 96769 327
> Email: andreas.sauer at brain.mpg.de
> www.brain.mpg.de
>
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip