Thanks Jan-Mathijs, that makes sense.<div><br></div><div>One more question - is it possible to just do partial coherence in fieldtrip? </div><div><br></div><div>Best wishes,</div><div><br></div><div>Ivana</div><div><br></div>
<div><br><div><br><div class="gmail_quote">On Tue, Nov 9, 2010 at 11:54 AM, jan-mathijs schoffelen <span dir="ltr"><<a href="mailto:jan.schoffelen@donders.ru.nl">jan.schoffelen@donders.ru.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word">Dear Ivana, <div><br></div><div>There is not so much information on the fieldtrip wiki as of yet. But I am working on it. </div><div>For the time being, perhaps you know that in order to compute partial directed coherence, you need to first fit an autoregressive model to your time domain data. This is necessary to obtain a thing which is known as the spectral transfer function, from which PDC will be derived.</div>
<div>Therefore you need to do two things before you can call ft_connectivityanalysis:</div><div><br></div><div>use ft_mvaranalysis to obtain the MVAR-model of your data.</div><div>use ft_freqanalysis (cfg.method = 'mvar') to obtain the spectral transfer function.</div>
<div><br></div><div>Note that you do not need to specify partchannel when you will be computing pdc; the idea is that by fitting a multivariate model to all channels of interest, the 'partialisation' is achieved. At least that's the theory...</div>
<div><br></div><div>I hope to find time to work on the documentation soon.</div><div><br></div><div>Best wishes,</div><div><br></div><div>Jan-Mathijs</div><div><br></div><div><br><div><div><div></div><div class="h5"><div>
On Nov 9, 2010, at 11:36 AM, Ivana Konvalinka wrote:</div><br></div></div><blockquote type="cite"><div><div></div><div class="h5">Hello,<div><br></div><div>I was wondering if it would be possible to get more information on partial directed coherence, using ft_connectivityanalysis. I've been trying to set it up on the frequency data of pairs of EEG electrodes, by partialling out motor evoked fields.</div>
<div><br></div><div>Hence, something like this:</div><div>cfg.method = 'pdc';</div><div>cfg.channelcmb = { pairs of electrodes here }; </div><div>cfg.partchannel = { electrodes containing fourier spectra of motor events };</div>
<div><br></div><div>pdc1 = ft_connectivityanalysis(cfg, freqs);</div><div><br></div><div>I get the following error: "<span style="font-family:arial, sans-serif;font-size:13px;border-collapse:collapse">reference to non-existent field 'transfer'". </span></div>
<div><font face="arial, sans-serif"><span style="border-collapse:collapse"><br></span></font></div><div><font face="arial, sans-serif"><span style="border-collapse:collapse">Is there any more documentation on this method in fieldtrip?</span></font></div>
<div><font face="arial, sans-serif"><span style="border-collapse:collapse"><br></span></font></div><div><font face="arial, sans-serif"><span style="border-collapse:collapse">Thanks in advance!</span></font></div> <div><font face="arial, sans-serif"><span style="border-collapse:collapse"><br>
</span></font></div><div><font face="arial, sans-serif"><span style="border-collapse:collapse">Ivana</span></font></div> <div><br></div><div><br></div><div>-- <br>Ivana Konvalinka<br>PhD Student<br>Interacting Minds Group<br>
Center of Functionally Integrative Neuroscience<br>University of Aarhus<br>Denmark<br><br><a href="http://www.interacting-minds.net" target="_blank">http://www.interacting-minds.net</a><br><a href="http://www.cfin.au.dk" target="_blank">http://www.cfin.au.dk</a><br>
<br> </div></div></div><p>--------------------------------------------------------------------------- You are receiving this message because you are subscribed to <br> the FieldTrip list. The aim of this list is to facilitate the discussion <br>
between users of the FieldTrip toolbox, to share experiences <br> and to discuss new ideas for MEG and EEG analysis. <br> See also <a href="http://listserv.surfnet.nl/archives/fieldtrip.html" target="_blank">http://listserv.surfnet.nl/archives/fieldtrip.html</a> <br>
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<div> <span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><div style="word-wrap:break-word">
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<div>Dr. J.M. (Jan-Mathijs) Schoffelen </div><div>Donders Institute for Brain, Cognition and Behaviour, <br>Centre for Cognitive Neuroimaging,<br>Radboud University Nijmegen, The Netherlands</div><div><a href="mailto:J.Schoffelen@donders.ru.nl" target="_blank">J.Schoffelen@donders.ru.nl</a></div>
<div>Telephone: 0031-24-3614793</div></div></span></div></span> </div><br></div></div><p>---------------------------------------------------------------------------
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</blockquote></div><br><br clear="all"><br>-- <br>Ivana Konvalinka<br>PhD Student<br>Interacting Minds Group<br>Center of Functionally Integrative Neuroscience<br>University of Aarhus<br>Denmark<br><br><a href="http://www.interacting-minds.net">http://www.interacting-minds.net</a><br>
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