<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Klados,<div><br></div><div>yes, you should keep the two conditions together. Otherwise, it is going to be hard to compare ICA component activities in the two conditions - you would have to find matching components and you would never know if the difference you observe between the two conditions for a given component pair is due to the difference in component carateristics (scalp projection, etc...) or if it due to the difference of brin activity in the two conditions. If you have the same components for both conditions, the first problem does not arise. So keep both conditions together and process the continuous file.</div><div><br></div><div>Hope this helps,</div><div><br></div><div>Arno<br><div><br><div><div>On Jan 12, 2010, at 11:42 PM, Marco Congedo wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hello Klados,<br><br> you can use the fact that you have two conditions explicitly to recover sources characteristic of each condition. The appropriate framework is described in length in<br><p class="title"><a href="http://www.ncbi.nlm.nih.gov/pubmed/18993114?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=2">On the blind source separation of human electroencephalogram by approximate joint diagonalization of second order statistics.</a></p><p class="rprtbody">Congedo M, Gouy-Pailler C, Jutten C.</p><span class="src"><span class="jrnl" title="Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology">Clin Neurophysiol</span>. 2008 Dec;119(12):2677-86. <br> <br>Cheers,<br>Marco Congedo<br>Senior Scientist, cnrs<br>GIPSA-lab Grenoble<br></span><br><div class="gmail_quote">On Tue, Jan 12, 2010 at 11:42 PM, Klados Manousos <span dir="ltr"><<a href="mailto:mklados@gmail.com">mklados@gmail.com</a>></span> wrote:<br> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Dear IIya<div><br></div><div>According to my opinion i suppose that you have to separate them because other pools of neuron (different sources) are activated with eyes opened and other with eyes closed...And if you see the mathematical background because you have a two condition experiment the underlying sources will be more than in one codition....so some sources will be merged in one component...i think that it is not preferable...it is better to reduce "normally" your data dimensionality by separating the recording session....and a 2 mins record is not a short epoch for ICA...There is an heuristic rule which says that ICA can be succesfully applied in epochs with sample points grater than channel^2 => Sample Points>= Channels^2.</div> <div><br></div><div>I hope to helped you...<br><br><div class="gmail_quote">2010/1/12 Ilya Adamchic <span dir="ltr"><<a href="mailto:dr.ilya@yahoo.com" target="_blank">dr.ilya@yahoo.com</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> <div class="im"> <div><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><p class="MsoNormal">Dear All.</p><p class="MsoNormal"><br> We have an experiment set up, when a patient should sit 2 min with eyes closed and 2 min with eyes open and so on several times. This is a spontaneous recording: no actions are performed in both conditions. When we perform ICA decomposition, is it reasonable to leave these 2 conditions mixed as a continuous file and let ICA decompose the continuous file. Or we need to separate eyes closed from eyes open conditions and only then perform ICA on the short epochs, which might be to short (2 min) for the 128 channel decomposition. <br> <br> Thank you all for your replies in advance.</p> </div><br> </div><br></div>_______________________________________________<br> Eeglablist page: <a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" target="_blank">http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br> To unsubscribe, send an empty email to <a href="mailto:eeglablist-unsubscribe@sccn.ucsd.edu" target="_blank">eeglablist-unsubscribe@sccn.ucsd.edu</a><br> For digest mode, send an email with the subject "set digest mime" to <a href="mailto:eeglablist-request@sccn.ucsd.edu" target="_blank">eeglablist-request@sccn.ucsd.edu</a><br></blockquote></div><br><br clear="all"> <br>-- <br>Klados A. Manousos<br> Research Assistant<br>Group of Applied Neurosciences<br>Lab of Medical Informatics, Medical School<br>Aristotle University of Thessaloniki<br>Thessaloniki, Greece<br>_________________________________________________<br> Tel: +30-2310-999332<br> Website: <a href="http://lomiweb.med.auth.gr/gan/mklados" target="_blank">http://lomiweb.med.auth.gr/gan/mklados</a><br><br><br><br> </div> <br>_______________________________________________<br> Eeglablist page: <a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" target="_blank">http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br> To unsubscribe, send an empty email to <a href="mailto:eeglablist-unsubscribe@sccn.ucsd.edu">eeglablist-unsubscribe@sccn.ucsd.edu</a><br> For digest mode, send an email with the subject "set digest mime" to <a href="mailto:eeglablist-request@sccn.ucsd.edu">eeglablist-request@sccn.ucsd.edu</a><br></blockquote></div><br><br clear="all"><br>-- <br>Marco Congedo<br> <a href="http://www.lis.inpg.fr/pages_perso/congedo/MC_Home.html">http://www.lis.inpg.fr/pages_perso/congedo/MC_Home.html</a><br> <span><ATT00001..txt></span></blockquote></div><br></div></div></body></html>