[FieldTrip] Source Reconstruction using Openmeeg method

[Mushfa Yousuf]

Hello Jörn;

I have calculated an indiviual leadfield for both EEG and MEG. The
structure of EEg and MEG shows the following variable

grid_meg =

        xgrid: [1x20 double]
        ygrid: [-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8]
        zgrid: [-2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13]
          dim: [20 17 16]
          pos: [5440x3 double]
         unit: 'cm'
       inside: [1x3177 double]
      outside: [1x2263 double]
          cfg: [1x1 struct]
    leadfield: {1x5440 cell}


grid_eeg =

        xgrid: [-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9]
        ygrid: [-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6]
        zgrid: [2 3 4 5 6 7 8 9 10 11]
          dim: [16 13 10]
          pos: [2080x3 double]
         unit: 'cm'
       inside: [1x1331 double]
      outside: [1x749 double]
          cfg: [1x1 struct]
    leadfield: {1x2080 cell}


Can you please give me a rough idea that how to concatenate the variables
from both structure ?


Thank you

Regards ;

Mushfa Yousuf


On Mon, May 13, 2013 at 11:13 AM, "Jörn M. Horschig" <
jm.horschig at donders.ru.nl> wrote:

>  Dear Mushfa,
>
> I think you have to compute two leadfield matrices, one for EEG (elec) and
> one for MEG (grad), and then concatenate these (and make sure that the
> order of sensors won't get mixed up anywhere, because  sourceanalysis just
> expects the leadfield matrix to be ordered like your data. If that's not
> the case, you either encounter the previous error you described or (if the
> number of channels matches, but order is mixed up) it will just return
> wrong source estimated activity.
>
> Best,
> Jörn
>
>
> On 5/6/2013 2:47 PM, Mushfa Yousuf wrote:
>
> Hello;
>
>  Yes you were right. I have defined the wrong sensors i.e 'grad' instead
> of 'elec' while calculating the Leadfield.
>
>  Actually I am trying to calculate Combined source reconstruction from
> both EEG and MEG sensors.
>
>  Do you have any idea, how to define both elec and grad definition  while
> calculating first forward then inverse solution.
>
>  Because in a fieldtrip either you can defined elec or grad at one time.
>
>
>  Regards;
>
>
>  Mushfa Yousuf
>
>  Neurozentrum,
> Universitätsklinikum Schleswig-Holstein,
> Campus Kiel (UKSH), Deutschland
>
>
> On Tue, Apr 30, 2013 at 6:23 PM, Johanna Zumer <johanna.zumer at gmail.com>wrote:
>
>> Hi Mushfa,
>>
>>  My guess is that the channels that have you used to compute .csdspctrm
>> are not the same as the channels in cfg.elec.    If you set cfg.channel =
>> freqPost.label, does that solve it?
>>
>>  Cheers,
>> Johanna
>>
>>
>> 2013/4/30 Mushfa Yousuf <mushfa.yousuf at googlemail.com>
>>
>>>   Hello Fieldtrippers,
>>>
>>>  I am doing source reconstruction using EEG channels on a fieldtrip.
>>>
>>>  I have computed Forward solution i.e head model using  'Openmeeg' and
>>> lead field successfully.
>>>
>>>  For the inverse solution using 'dics' method, I wrote the following
>>> syntax
>>>
>>>
>>>
>>>
>>>
>>>   cfg              = [];
>>>   cfg.method       = 'dics';
>>>  cfg.frequency    = 130;
>>>  cfg.elec         = dataFIC12.hdr.elec;
>>>  cfg.grid         = grid;
>>>  cfg.vol          = vol;
>>>
>>>   sourcePost = ft_sourceanalysis(cfg, freqPost);
>>>
>>>
>>>  and I have received the following error:
>>>
>>>
>>>  ??? Error using ==> mtimes
>>> Inner matrix dimensions must agree.
>>>
>>>  Error in ==> beamformer_dics at 314
>>>         filt = pinv(lf' * invCf * lf) * lf' * invCf;              %
>>>         Gross eqn. 3, use PINV/SVD to cover rank deficient
>>>         leadfield
>>>
>>>  Error in ==> ft_sourceanalysis at 595
>>>       dip(i) = beamformer_dics(grid, sens, vol, [],
>>>       squeeze(Cf(i,:,:)), optarg{:});
>>>
>>>  Error in ==> newCode at 214
>>> sourcePost = ft_sourceanalysis(cfg, freqPost);
>>>
>>>
>>>
>>>
>>>  Any help would be appreciated.
>>>
>>>
>>>  Regards;
>>>
>>>
>>>  Mushfa Yousuf
>>>
>>>  Neurozentrum,
>>> Universitätsklinikum Schleswig-Holstein,
>>> Campus Kiel (UKSH), Deutschland
>>>
>>>
>>>  _______________________________________________
>>> fieldtrip mailing list
>>> fieldtrip at donders.ru.nl
>>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>>
>>
>>
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>
>
>
> _______________________________________________
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>
>
>
> --
> Jörn M. Horschig
> PhD Student
> Donders Institute for Brain, Cognition and Behaviour
> Centre for Cognitive Neuroimaging
> Radboud University Nijmegen
> Neuronal Oscillations Group
> FieldTrip Development Team
>
> P.O. Box 9101
> NL-6500 HB Nijmegen
> The Netherlands
>
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> Tel:    +31-(0)24-36-68493
> Web: http://www.ru.nl/donders
>
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>
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