<div dir="ltr">Dear Germano and Jeff,<div><br></div><div>SCCN's rule of thumb is that you need 30*(number of channels)^2 datapoints for good ICA results. The first 30 should go up as the number of channels goes up.</div><div><br></div><div><span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:14.857142448425293px">> Do you mean I should get more than 1-3 eye movement related components?</span><br></div><div><br></div><div>Yes.</div><div><br></div><div><span style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:14.857142448425293px">> What do you suggest to try to improve the decomposition? I know there are some free parameters I could try, but what should I try first?</span><br></div><div class="gmail_extra"><br></div><div class="gmail_extra">Try 'pca' option when you run infomax. 'pca', X (X is a number) so that X meets the above equation. It does not guarantee to improve your decomposition though, since decomposition quality also depends on how clean your data are.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Makoto</div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Dec 4, 2014 at 3:56 PM, K Jeffrey Eriksen <span dir="ltr"><<a href="mailto:eriksenj@ohsu.edu" target="_blank">eriksenj@ohsu.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Makoto,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Thanks for your response. I believe I successfully obtained eye movement components 10-12 years ago with 10 or 11 minutes of 256-channel, 250 sps EEG.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Do you mean I should get more than 1-3 eye movement related components?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">What do you suggest to try to improve the decomposition? I know there are some free parameters I could try, but what should I try first?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Thanks,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">-Jeff<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span style="font-size:10pt;font-family:Tahoma,sans-serif">From:</span></b><span style="font-size:10pt;font-family:Tahoma,sans-serif"> Makoto Miyakoshi [mailto:<a href="mailto:mmiyakoshi@ucsd.edu" target="_blank">mmiyakoshi@ucsd.edu</a>]
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<b>Sent:</b> Thursday, December 04, 2014 11:33 AM<br>
<b>To:</b> K Jeffrey Eriksen<br>
<b>Cc:</b> <a href="mailto:eeglablist@sccn.ucsd.edu" target="_blank">eeglablist@sccn.ucsd.edu</a><br>
<b>Subject:</b> Re: [Eeglablist] removing eye blinks from 256 channel EEG<u></u><u></u></span></p><div><div class="h5">
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Dear Jeff,<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">> My epochs range from 3 to 20 minutes.</span><u></u><u></u></p>
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<p class="MsoNormal">Sounds too short for 256ch decomposition. You need at least > 1 million datapoints for it. Using high sampling rate such as 1000Hz increases apparent datapoints, but I'm not sure how it helps.<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">> I generally find 1-3 ICs for each subject.</span><u></u><u></u></p>
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<p class="MsoNormal">This sounds too few for 256ch decomposition.<u></u><u></u></p>
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<p class="MsoNormal">> <span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">general background noise goes UP after these 1-3 components are removed.</span><u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">If the removed components are coupled with other components that cancels out each other, this could happen. However that's kind of rare and I don't see it very
often... most likely your decomposition has problems.</span><u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">Makoto</span><u></u><u></u></p>
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<p class="MsoNormal">On Wed, Nov 26, 2014 at 3:18 PM, K Jeffrey Eriksen <<a href="mailto:eriksenj@ohsu.edu" target="_blank">eriksenj@ohsu.edu</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">EEGlabbers:<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">Does anyone out there have particular experience from removing eye blinks from 256 channel EEG data using ICA? I have started to apply it to 11 subjects with
data recorded at 1,000 frame/sec, bandpass filtered & downsampled to 250 fps. My epochs range from 3 to 20 minutes. I generally find 1-3 ICs for each subject. When I remove these, there is still visible remnants around the time of each eye blink. Of more concern
is that the general background noise goes UP after these 1-3 components are removed.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">Any ideas that might improve my results? I can post some screenshots if need be.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">Thanks,<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Calibri,sans-serif;color:black">-Jeff<u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">-- <u></u><u></u></p>
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<p class="MsoNormal">Makoto Miyakoshi<br>
Swartz Center for Computational Neuroscience<br>
Institute for Neural Computation, University of California San Diego<u></u><u></u></p>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr">Makoto Miyakoshi<br>Swartz Center for Computational Neuroscience<br>Institute for Neural Computation, University of California San Diego<br></div></div>
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