[FieldTrip] Resting State EEG Connectivity

[Eelke Spaak]

Dear Elene,

Have a look at ft_sourceparcelllate and the following tutorial,
particularly the part about parcellation:
http://www.fieldtriptoolbox.org/tutorial/networkanalysis/ .

Cheers,
Eelke


On Wed, 8 May 2019 at 08:57, Elene Beitia Loinaz
<elene.beitia at alumni.mondragon.edu> wrote:
>
> Dear all,
>
> Continuing with the connectivity issue, we have seen that the problem of memory come from the size of the leadfield`s grid used previously for source reconstruction and now for connectivity. The variable related with that grid is data.pos,  which was created in ft_prepareleadfield. This value contains the coordinates of the centroids' voxels, related with the grid. As this variable is too large, it supposes really high computational effort that matlab cannot handle.
>
> We want to cluster the data.pos voxels coordinates into different brain regions such as: temporal area, frontal field....
>
> Does anyone know how we can group those coordinates into regions in order to decrease the size of data.pos variable needed in ft_connectivityanalysis function?
>
> Thank you in advanced.
>
> Hau idatzi du Elene Beitia Loinaz (elene.beitia at alumni.mondragon.edu) erabiltzaileak (2019 mai. 7, ar. (11:11)):
>>
>> Hi Fieldtripers,
>>
>> We are trying to perform a conectivity analysis using source reconstructed data. We have seen that ft_connectivityanalysis can be calculated using the output of ft_freqanalysis or ft_sourceanalysis. Someone knows which are the benefits of using the results obtain in ft_sourceanalysis to perform the connectivity analysis?
>>
>> Furthemore, we have problems when we compute the choerence approach with the source reconstructed data.
>>
>> Our code:
>>
>> cfg           = [];
>> cfg.method    = 'coh'
>> coh           = ft_connectivityanalysis(cfg, beamformer);
>>
>> The error that we obtain is:
>> Out of memory. Type "help memory" for your options.
>>
>> Error in univariate2bivariate (line 314)
>>          data.crsspctrm = (transpose(mom)*conj(mom))./nrpt;
>>
>> Error in ft_connectivityanalysis (line 449)
>> [data, powindx, hasrpt] = univariate2bivariate(data, 'mom', 'crsspctrm', dtype, 'cmb', cfg.refindx,'keeprpt', 0);
>>
>> This segment of code has been concluded following the tutorials below:
>> http://www.fieldtriptoolbox.org/tutorial/networkanalysis/
>> http://www.fieldtriptoolbox.org/tutorial/connectivity/
>> http://www.fieldtriptoolbox.org/workshop/meg-uk-2015/fieldtrip-connectivity-demo/
>>
>> Thank you in advanced,
>>
>> Waiting for your answer.
>
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