[FieldTrip] Reference to non-existent field 'mom' in ft_connectivityanalysis

Davide Sometti davide.sometti-1 at studenti.unitn.it
Wed May 15 12:28:34 CEST 2019


Thanks a lot  for the answers.

Best,
Davide S.


Il giorno mer 15 mag 2019 alle ore 11:56 Schoffelen, J.M. (Jan Mathijs) <
jan.schoffelen at donders.ru.nl> ha scritto:

> Hi all,
>
> Allow me to correct Eelke’s statement a bit: *in the context of what
> Davide wants to do* ft_connectivityanalysis requires single trial input.
> This is not true in general.
>
> Best wishes,
> Jan-Mathijs
>
>
> On 15 May 2019, at 10:49, Eelke Spaak <e.spaak at donders.ru.nl> wrote:
>
> Dear Davide,
>
> ft_connectivityanalysis requires individual trials, and the
> combination of 'fourier' - 'pcc' is the only combination there that
> results in individual trial estimates. Internally, I think the 'pcc'
> beamformer basically computes the exact same filters as DICS, it just
> has a somewhat different (i.e. more flexible) approach to data
> bookkeeping, allowing straightforward filtering of individual trials.
>
> Best,
> Eelke
>
> On Tue, 14 May 2019 at 15:27, Davide Sometti
> <davide.sometti-1 at studenti.unitn.it> wrote:
>
>
> Dear community,
>
> I’m trying to perform connectivity analysis (Matlab 2018b, FieldTrip
> 2018-12-11), in order to obtain the absolute part of the imaginary
> coherence. Here are the steps that I’ve used in order to perform it.
>
> 1-     First I performed the frequency analysis, on the single condition
> (not showed), and on all the conditions together
>
> cfg = [];
>
> cfg.channel    = chn;
>
> cfg.method     = 'mtmfft';
>
> cfg.output     = 'powandcsd';
>
> cfg.taper      = 'dpss';
>
> cfg.keeptrials ='no';
>
> cfg.keeptapers ='no';
>
> cfg.tapsmofrq  = 3;
>
> cfg.foi        = [6; 11; 16; 21; 26; 40];
>
> data_freq_all  = ft_freqanalysis(cfg, data_reject_all);
>
>
>
> 2-     I computed the beamformer filters based on the entire data
>
> cfg=[];
>
> cfg.method='dics';
>
> cfg.frequency=6;
>
> cfg.grid=lf;
>
> cfg.grid.pos=pos;
>
> cfg.grid.tri=tri;
>
> cfg.headmodel=hdm;
>
> cfg.senstype     = 'meg';
>
> cfg.dics.projectnoise = 'yes';
>
> cfg.dics.lambda       = '5%';
>
> cfg.dics.keepfilter   = 'yes';
>
> cfg.dics.realfilter   = 'yes';
>
> cfg.dics.keepcsd       = 'yes';
>
> cfg.dics.keepmom       = 'yes';
>
> cfg.dics.fixedori     = 'yes';
>
> sourceAll = ft_sourceanalysis(cfg,data_all);
>
>
>
> 3-     I've then performed the source analysis on each of the four
> conditions, using the precomputed filter
>
> cfg.grid.filter=sourceAll.avg.filter;
>
>
>
> source_pre_incl=ft_sourceanalysis(cfg,data_pre_incl);
>
> source_pre_excl=ft_sourceanalysis(cfg,data_pre_excl);
>
> source_post_incl=ft_sourceanalysis(cfg,data_post_incl);
>
> source_post_excl=ft_sourceanalysis(cfg,data_post_excl);
>
>
>
> 4-     Finally I’ve performed the connectivity analysis
>
>
>
>
>
> cfg=[];
>
> cfg.method  ='coh';
>
> cfg.complex = 'absimag';
>
> source_conn = ft_connectivityanalysis(cfg, source_pre_incl);
>
>
>
> When I try to run the connectivity analysis I get this error, and I cannot
> go further in the analysis.
>
>
>
> Reference to non-existent field 'mom'.
>
>
>
> Error in univariate2bivariate (line 225)
>
>      sizmom = size(data.mom{data.inside(1)});
>
>
>
> Error in ft_connectivityanalysis (line 449)
>
>        [data, powindx, hasrpt] = univariate2bivariate(data, 'mom',
> 'crsspctrm', dtype, 'cmb', cfg.refindx, 'keeprpt', 0);
>
>
>
>
>
> I’ve tried different solution, changing output for the frequency analysis
> and method for the beamforming, like follow:
>
>
>
> 'fourier' - 'pcc'
>
> 'powandcsd' - 'pcc'
>
> 'fourier' - 'dics'
>
> The combination fourier and pcc was the only one that worked, among the 4,
> the others always gave me the same error, as above. I’m wondering why even
> if I’ve specified cfg.keepmom=’yes’, this one is not present in the
> structure after the source analysis.
>
> Anyone that could help me?
>
> Davide S.
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