<div dir="ltr">Dear Jeff,<div><br></div><div>If your data is 10 min and 1000Hz sampled, you have 600,000 data points. Divide 600,000 with 30 and square root it. You get 140. So use 'pca', 140. I would recommend 'pca', 70 or lower to give it a good margin.</div><div><br></div><div>Makoto</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Dec 4, 2014 at 6:50 PM, Eriksen, Jeffrey :LGS Neurodiagnostics <span dir="ltr"><<a href="mailto:JEriksen@lhs.org" target="_blank">JEriksen@lhs.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">





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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Makato,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Thanks for reminding me of the formula. Now that I have looked at 10 and 20 minute decompositions, it seems to be working better. Of course, I am still well
 below the 30x factor. I will try your ‘pca’ option as well, but I do not understand what X is. Is X the 30 (or a lower or higher value), or is X the number of data points?
<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">-Jeff<u></u><u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:eeglablist-bounces@sccn.ucsd.edu" target="_blank">eeglablist-bounces@sccn.ucsd.edu</a> [mailto:<a href="mailto:eeglablist-bounces@sccn.ucsd.edu" target="_blank">eeglablist-bounces@sccn.ucsd.edu</a>]
<b>On Behalf Of </b>Makoto Miyakoshi<br>
<b>Sent:</b> Thursday, December 04, 2014 6:30 PM</span></p><div><div class="h5"><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></div></div><p></p><div><div class="h5">
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Dear Germano and Jeff,<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">> Do you mean I should get more than 1-3 eye movement related components?</span><u></u><u></u></p>
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<p class="MsoNormal">Yes.<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:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">> 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><u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">Makoto<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Thu, Dec 4, 2014 at 3:56 PM, K Jeffrey Eriksen <<a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__mailto-3Aeriksenj-40ohsu.edu&d=AAMFaQ&c=5aMxbibQyX6B-W2mpD2HYH5lwK3h7A1hIsNQieXCZKA&r=RW9gWwlQ_echeF9GoAB-bw&m=1L894JApoM0afiTll4HrtL0s3mCkc9RKPnHk_qjFlaY&s=JN7WdfuI4xbLDmbGZLvRzolYZ6Ps1ODU2zbaUytWa-Q&e=" target="_blank">eriksenj@ohsu.edu</a>>
 wrote:<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Makoto,</span><u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">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.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Do you mean I should get more than 1-3 eye movement related components?</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">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><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Thanks,</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">-Jeff</span><u></u><u></u></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Makoto Miyakoshi [mailto:<a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__mailto-3Ammiyakoshi-40ucsd.edu&d=AAMFaQ&c=5aMxbibQyX6B-W2mpD2HYH5lwK3h7A1hIsNQieXCZKA&r=RW9gWwlQ_echeF9GoAB-bw&m=1L894JApoM0afiTll4HrtL0s3mCkc9RKPnHk_qjFlaY&s=itl5_2QIm-QQ8wrv2IyZ13cYYwm4gKnPIGTPmesu42w&e=" target="_blank">mmiyakoshi@ucsd.edu</a>]
<br>
<b>Sent:</b> Thursday, December 04, 2014 11:33 AM<br>
<b>To:</b> K Jeffrey Eriksen<br>
<b>Cc:</b> <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__mailto-3Aeeglablist-40sccn.ucsd.edu&d=AAMFaQ&c=5aMxbibQyX6B-W2mpD2HYH5lwK3h7A1hIsNQieXCZKA&r=RW9gWwlQ_echeF9GoAB-bw&m=1L894JApoM0afiTll4HrtL0s3mCkc9RKPnHk_qjFlaY&s=ZP83Yy9d1NyZcAOgolQh1Oa1acrC6-JyuZg4DIfxSQY&e=" target="_blank">
eeglablist@sccn.ucsd.edu</a><br>
<b>Subject:</b> Re: [Eeglablist] removing eye blinks from 256 channel EEG</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">Dear Jeff,<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">> My epochs range from 3 to 20 minutes.</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">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"> <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"> <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"> <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"> <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="https://urldefense.proofpoint.com/v2/url?u=http-3A__mailto-3Aeriksenj-40ohsu.edu&d=AAMFaQ&c=5aMxbibQyX6B-W2mpD2HYH5lwK3h7A1hIsNQieXCZKA&r=RW9gWwlQ_echeF9GoAB-bw&m=1L894JApoM0afiTll4HrtL0s3mCkc9RKPnHk_qjFlaY&s=JN7WdfuI4xbLDmbGZLvRzolYZ6Ps1ODU2zbaUytWa-Q&e=" 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:</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">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.</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"> </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">Any ideas that might improve my results? I can post some screenshots if need be.</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">Thanks,</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">-Jeff</span><u></u><u></u></p>
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_______________________________________________<br>
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<p class="MsoNormal">--
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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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<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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