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<p class="MsoNormal">Hi FieldTrip Community !</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am trying to compute spectrally resolved Granger causality on (i)EEG data using the parametric approach, with mvar modelling. At this level, it is easier for my data than non parametric modelling.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">From the original data, I have selected two channels to compute Granger causality from channel 1 to channel 2 and from channel 2 to channel 1.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am currently struggling with the last step, from which I am expecting an output in the form of a 4-D structure containing the Granger causality power for each selected frequency and each time point for :</p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Channel 1 to channel 1 (not very informative)</li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Channel 1 to channel 2</li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Channel 2 to channel 1</li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Channel 2 to channel 2 (not very informative)</li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To do so, I am using the function <i>ft_connectivity_granger</i>, which I think is suited for spectrally resolved Granger causality, also while keeping the time dimension.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here is my sloppy code :</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><i>[mvar_granger, V, n] = ft_connectivity_granger(mvar_freq.transfer, mvar_freq.noisecov, ...<o:p></o:p></i></p>
<p class="MsoNormal"><i> mvar_freq.crsspctrm, 'dimord', 'chan_chan_freq_time');<o:p></o:p></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In which mvar_freq is the structure obtained after ft_mvaranalysis and transformed into the frequency domain with ft_freqanalysis_mvar. To be honest, I don’t know what V stands for in the output.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here are the dimords of the mvar_freq fields used as inputs:</p>
<p class="MsoNormal">Transfer (H) and crsspctrm (S): chan_chan_freq_time</p>
<p class="MsoNormal">Noisecov (Z) : chan_chan_freq</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">After running the previous line, I do not get an error, but a mvar_granger structure in 3D containing a lot of 0 values. Honestly, I don’t really understand what it represents.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">If someone knows how to work with ft_connectivity_granger in such a way that I can get the kind of output I am looking for (probably something like chan_chan_freq_time, right ?), I am all ears to your wisdom !</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would be very thankful for any help on this topic <span style="font-family:"Segoe UI Emoji",sans-serif">😊</span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Cheers !</p>
<p class="MsoNormal">Eva</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">PS : Thanks a lot for this FieldTrip mailing list. I am learning so much thanks to it !</p>
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