[FieldTrip] Spatio-temporal cluster-based permutation analysis on EEG sources

Eelke Spaak eelke.spaak at donders.ru.nl
Fri Oct 31 13:29:30 CET 2014

Dear Emma,

I've not read your full post, but can say this about the latter part:
fieldnames() should be a builtin MATLAB command. Most likely your
version of MATLAB is too old; could you try using a more recent
version? Typically we try to support versions up to 5 years old for
use with FieldTrip.

Hope that helps,

On 31 October 2014 13:19, Emma Holmes <eh776 at york.ac.uk> wrote:
> Dear all,
> I am trying to perform spatio-temporal cluster statistics to the sources of
> an EEG dataset, which I localised using the SPM8 toolbox.
> For each participant (averaged across trials), I have a .nii image
> containing the source reconstruction for each of two conditions at multiple
> different time points. Each nifti file contains a matrix of 91 x 109 x 91,
> which corresponds to the source estimates at each voxel.
> My aim is to identify sources of activity that span large clusters of voxels
> and/or time points, similar to what I have done previously with the scalp
> data.
> I understand that the function 'ft_sourcestatistics' should be able to
> achieve this with the data output from the function 'ft_sourcegrandaverage'.
> However, I am having difficulty structuring the data from the nifti files in
> a format that can be successfully input to 'ft_sourcegrandaverage'.
> The data that I am trying to input to 'ft_sourcegrandaverage' contains a
> cell array of structures--one for each participant.
> As far as I understand from the documentation, each structure should contain
> a 'pos' field, which specifies the [x y z] co-ordinates for each position in
> the matrix (in my case, a matrix of size 91*109*91 x 3).
> I have also included a 'time' field, containing a vector of the time points
> to which each .nii image corresponds and a 'dim' field containing the vector
> [91 109 91].
> Could you please let me know whether or not this is correct and in which
> field(s) I should subsequently add the source reconstruction estimates at
> each time point.
> So far, I have tried including an 'avg' field with the data at each time
> point (91 x 109 x 91 x ntps).
> However, when I do so, I get the following error:
> ??? Undefined function or method 'fieldnames' for input arguments of type
> 'double'.
> Error in ==> parameterselection at 47
>     tmp = fieldnames(data.avg);
> Error in ==> ft_checkdata at 578
>   param = setdiff(parameterselection('all', data), exclude);
> Error in ==> ft_sourcegrandaverage at 81
>   varargin{i} = ft_checkdata(varargin{i}, 'datatype', {'source'},
> 'feedback', 'no',
>   'inside', 'logical', 'sourcerepresentation', 'new');
> I am using matlab version (R2008b) and fieldtrip-20140415
> (although I have also tried other fieldtrip versions).
> Any help would be greatly appreciated.
> Best wishes,
> Emma

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