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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">You may want to see
<a href="https://sccn.ucsd.edu/pipermail/eeglablist/2014/007810.html">https://sccn.ucsd.edu/pipermail/eeglablist/2014/007810.html</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-Iman<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"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-------------------------------------------------------------<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Iman M.Rezazadeh, Ph.D<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Semel Intitute, UCLA , Los Angeles<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">& Center for Mind and Brain, UC DAVIS, Davis<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"><o:p> </o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></a></p>
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<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"> eeglablist-bounces@sccn.ucsd.edu [mailto:eeglablist-bounces@sccn.ucsd.edu]
<b>On Behalf Of </b>Ahmad, Jumana<br>
<b>Sent:</b> Friday, December 9, 2016 10:02 AM<br>
<b>To:</b> Eric HG <erichg2013@gmail.com>; eeglablist <eeglablist@sccn.ucsd.edu><br>
<b>Subject:</b> Re: [Eeglablist] Artifacts after removal of ICA component<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Eric,<o:p></o:p></span></p>
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<span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Did you reduce the rank of your data by 1 before running ICA? I would do Matlab rank(EEG.data(:,:)) and check it is not 1 less than the number of your channels in ICA.
If it is the same and you are not rank deficient. If you are then you can perform channel rejection to match EEG.nbchan with rank(EEG.data(:,:)).<o:p></o:p></span></p>
<p style="mso-margin-top-alt:4.8pt;margin-right:0in;margin-bottom:6.0pt;margin-left:0in;line-height:18.0pt;background:white">
<span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Average referencing reduces the rank of the data by 1. When you rereference to average, the sum of all your channels is 0 at each time point. One channel is therefore
a linear combination of the others, which implies statistical dependence, therefore the dimensionality of your data is reduced by one after averaging. I always average reference after ICA.
<o:p></o:p></span></p>
<p style="mso-margin-top-alt:4.8pt;margin-right:0in;margin-bottom:6.0pt;margin-left:0in;line-height:18.0pt;background:white">
<span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Average referencing before means you can only extract N-1 independent components after this. This is fine as long as you remember to extract 1 component less than you
would have before average reference.<o:p></o:p></span></p>
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<span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Best wishes,<o:p></o:p></span></p>
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<span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Jumana
</span><span lang="EN-GB" style="font-size:9.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><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">
<a href="mailto:eeglablist-bounces@sccn.ucsd.edu">eeglablist-bounces@sccn.ucsd.edu</a> [<a href="mailto:eeglablist-bounces@sccn.ucsd.edu">mailto:eeglablist-bounces@sccn.ucsd.edu</a>]
<b>On Behalf Of </b>Eric HG<br>
<b>Sent:</b> 08 December 2016 00:39<br>
<b>To:</b> eeglablist <<a href="mailto:eeglablist@sccn.ucsd.edu">eeglablist@sccn.ucsd.edu</a>><br>
<b>Subject:</b> [Eeglablist] Artifacts after removal of ICA component<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt">Hi everybody,</span><span lang="EN-GB"><o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt">I've had some trouble with removal of components using ICA (I'm currently using ICA infomax). After I remove a component there seems to be induced high frequency noise in the dataset. <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt">The data is referenced to average before applying ICA. <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt">Does anyone know why that is happening? <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt">Best,<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="font-size:9.5pt">Eric<o:p></o:p></span></p>
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