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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Dear Helen,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Great to hear that you liked the paper! <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>When computing Granger causality you get by default two values, x->y and y->x. I am not sure what more to say to answer your question, so here’s a slightly more detailed response on what we did to the data ;)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>We did statistics in a two step procedure. First, identifying regions of interest using a surrogate distribution and a permutation test on the z-transformed coherence metric. Second, computing the Granger causality metric and performing an ANOVA (after log-transforming the Granger values to make them satisfy the normality requirement). For both steps, I used FieldTrip functions only for computing the connectivity metric (ordinary coherence, and Granger causality, respectively). Everything else is something I am afraid you will have to do manually (but you can grab some bits and pieces of existing FT functions). I do not have access to my old drive at the Donders Institute anymore, so I cannot send you the code, but I am confident that you can manage to re-code this :) If you get stuck, however, feel free to let me know and I can give you a hand.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>With best regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Jörn<o:p></o:p></span></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span style='font-size:9.0pt;font-family:"Verdana",sans-serif;color:#1F497D;mso-fareast-language:NL'>--</span></b><b><span style='font-size:9.0pt;font-family:"Verdana",sans-serif;color:#255A9E;mso-fareast-language:NL'><br>Jörn M. Horschig, PhD</span></b><span style='font-size:9.0pt;font-family:"Verdana",sans-serif;color:#626264;mso-fareast-language:NL'>, Software Engineer<br><a href="http://www.artinis.com/" target="_blank"><span style='color:#626264'>Artinis Medical Systems</span></a> | +31 481 350 980 </span><b><span style='font-size:9.0pt;font-family:"Verdana",sans-serif;color:#255A9E;mso-fareast-language:NL'><o:p></o:p></span></b></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> Helen Wieffering [mailto:helen.wieffering@gmail.com] <br><b>Sent:</b> Monday, February 29, 2016 1:26<br><b>To:</b> FieldTrip discussion list <fieldtrip@science.ru.nl>; jorn@artinis.com<br><b>Subject:</b> Granger Causality statistics and group analysis<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>Dear J<span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:black'>ö</span>rn, <o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>I recently re-read your 2015 paper on Directed Communication between Nucleus Accumbens and Neocortex in Humans. I am taking a similar approach with my data, looking at non-parametric Granger Causality as computed through FieldTrip. I believe you pointed me to this paper in a response to one of my FieldTrip e-mails a few months back, and it has proven very helpful!<o:p></o:p></p></div></div><p class=MsoNormal style='margin-bottom:12.0pt'>If it's not too much trouble, I now wonder if you could provide any further detail on how you computed p-value statistics from each subject's Granger spectrum. As far as I can tell, Fieldtrip's statistical packages are very limited / nonexistent when it comes to connectivity data. In your paper you mentioned obtaining one Granger estimate for each direction - could you explain how you did this, and whether you performed this statistical analysis in Fieldtrip? <o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>Any advice is much appreciated! Thank you,<o:p></o:p></p></div><p class=MsoNormal>Helen <o:p></o:p></p></div></div></div></body></html>