<div dir="ltr">Dear Georges,<div><br></div><div>If you remove IC and reconstruct channel EEG by backprojecting the remaining ICs, of course it changes channel EEG phase!</div><div><br></div><div>Here is our EEGLAB workshop 2013 materials. You can find several powerpoint/pdf files that explains how ICA works on data cleaning.</div><div><a href="http://sccn.ucsd.edu/wiki/EEGLAB_2013_UCSD">http://sccn.ucsd.edu/wiki/EEGLAB_2013_UCSD</a><br></div><div><br></div><div>Makoto</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Sep 13, 2014 at 7:50 AM, otte georges <span dir="ltr"><<a href="mailto:georges.otte@pandora.be" target="_blank">georges.otte@pandora.be</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="NL-BE" link="#0563C1" vlink="#954F72"><div><p class="MsoNormal"><span lang="EN-US">Dear ICA experts<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">There is some discussion going on about the evidence that reconstructing an multichannel EEG after ICA decomposition and removing one or two artefact components could result in  scrambling the phase content (and coherence) of the reconstructed signals. Fi starting from a 19 ch EEG, removing two components with fi electrode pops and sweat artefacts , reconstructing the 19 ch EEG from 17 components (taking out the artefact containing ones)  without those artefacts. <u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Others say that this is not the case and that ICA respects the phase. However many authors (Zeman, Thatcher..) have published very convincing data to the contrary.<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Any suggestions how to evaluate this ? Is it known from the algorithm what the reconstruction  will do to the phase content (imaginary part of the signal) ?<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">All help is very welcome<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Sincerely<span class="HOEnZb"><font color="#888888"><u></u><u></u></font></span></span></p><span class="HOEnZb"><font color="#888888"><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Georges<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><u></u> <u></u></p></font></span></div></div><br>_______________________________________________<br>
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