[FieldTrip] Specific sources and ft_sourcestatistics

Laura Rueda Delgado Laura.Rueda at faber.kuleuven.be
Mon Oct 20 18:17:25 CEST 2014

Dear all,

I'm working with EEG data and the individual MRIs. I have a doubt about a step for defining ROIs. I have EEG data during a task with 3 conditions (C1, C2, C3) and during rest. I would like to know what is the main effect of the conditions in my source data. I was recommended to use the contrast of Task (C1, C2 and C3 together) vs Rest to obtain meaningful sources, which then are used to restrict the source and statistical analysis between the conditions. This is what I do:

-          Estimate sources with the common filter for Task and Rest separately.

-          Find sources that are significantly different between these two conditions (ft_sourcestatistics with dependent T).

-          Use the position of these sources as ROIs in ft_sourceanalysis for C1, C2 and C3 separately (but using a common filter of these conditions).

-          Find sources that account for the main effect between conditions (ft_sourcestatistics with dependent F).

Now the problem is that if I use the position of the sources in ft_sourceanalysis, I don't have a regular grid anymore, and this becomes a problem when using ft_sourcestatistics as cfg.dim needs to be specified and if I do not specify it (because I don't have a regular grid with 3 dimensions as expected), I get the following error:

Error using reshape
To RESHAPE the number of elements must not change.

Error in clusterstat (line 185)
      posclusobs = findcluster(reshape(postailobs, [cfg.dim,1]),channeighbstructmat,cfg.minnbchan);

Error in ft_statistics_montecarlo (line 361)
  [stat, cfg] = clusterstat(cfg, statrand, statobs);

Error in statistics_wrapper (line 308)
    [stat, cfg] = statmethod(cfg, dat, design);

Error in ft_sourcestatistics (line 107)
    [stat, cfg] = statistics_wrapper(cfg, varargin{:});

So does anybody know a way to work around this?

And what do you think of the logic of these steps?

Thank you in advance for any help!


Laura Rueda Delgado

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