<div dir="ltr">Dear Hui-bin,<div><br></div><div>> How to remove the VEOG & HEOG signals perfectly without losing the genuine brain signals?<div class="gmail_extra"><br></div><div class="gmail_extra">We recommend ICA (of course, since you are posting to EEGLAB mailing list!) to separate VEOG and HEOG from EEG. See DElorme et al. (2007) NeuroImage for artifact rejection using ICA. However, it seems naive to ask for 'perfect' separation. What do you mean, and how do you define, the 'perfect' separation if we don't have ground truth measured?</div><div class="gmail_extra"><br></div>> 1. If I want to use ICA to remove artifacts, is it a good idea that the VEOG channel is excluded before run ICA ? The HEOG channel is placed on the tip of nose, and the VEOG channel is placed below the eyelid of the left eye.<br><br>Of course yes.<br><br>> 2. Before run ica, the continuous EEG data was segmented into stimulus-locked ERP epochs of 3000ms(-1000ms to 2000ms) and filtered at 1~30Hz. Is it necessary that the epochs is baseline corrected?<br><br>Do not correct baseline. See Groppe et al. (2010) NeuroImage paper for 'split half...'<br><br>> 3. When should I re-reference the channels to the channel on the tip of nose(i.e., the HEOG channel)? Before run ICA or after the independent components related to VEOG &HEOG is removed?</div><div><br></div><div>Before ICA and after bad-channel rejection. Re-reference to average, don't use nose tip unless you want to replicate the published results. Don't remove EOG channels.</div><div><br>> 4. How to efficiently identify the ICs that related to VEOG & HEOG. Is it a good idea to calculate the Pearson correlation coefficients between ICs and VEOG channel ?</div><div><br></div><div>You need either experience or Nima's eyeCatch() that is included in his Measure Projection Toolbox (Bigdely-Shamlo et al., 2013 NeuroImage). It's not that difficult, and you should also learn it too anyways.</div><div><br></div><div>Makoto<br></div><div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Oct 21, 2014 at 5:24 AM, Hui-bin Jia <span dir="ltr"><<a href="mailto:420247417@qq.com" target="_blank">420247417@qq.com</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"><div>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4">Hi, all</font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><u></u><u></u><font size="4"></font><u></u></span> </p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4"> In my ERP experiment, all EEG electrodes were referenced online to FCz. </font></span><font size="4"><span lang="EN-US" style="font-family:'Times New Roman',serif">But during the </span><span lang="EN-US" style="font-family:'Times New Roman',serif">preprocessing of EEG data, they should be re-referenced to the channel on the tip of nose. </span></font></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><u></u><font size="4"></font><u></u></span> </p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4"> Because the tip of nose is in the vicinity of eyes, it has a lot of VEOG signals. If VEOG and HEOG signals are partly removed by ICA, using this channel as reference </font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4">may seriously affect the result. So in order to gain reasonable ERP waveforms, the VEOG & HEOG signals should be perfectly removed. <span> </span></font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><span><font size="4"></font></span></span> </p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4"><span></span><u></u><u></u></font></span> </p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="5"> Could someone give me some tips and cautions during the preprocessing?<span> How to remove the VEOG & HEOG signals perfectly </span></font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="5"><span>without losing the genuine brain signals?</span></font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4"><span></span><u></u><u></u></font></span> </p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4"> Besides I have the following questions:<u></u><u></u></font></span></p>
<p style="margin:0cm 0cm 0pt 18pt"><font size="4"><span lang="EN-US" style="font-family:'Times New Roman',serif"><span>1.<span style="font-style:normal;font-variant:normal;font-weight:normal;font-size:7pt;line-height:normal;font-family:'Times New Roman'"> </span></span></span><span lang="EN-US" style="font-family:'Times New Roman',serif">If I want to use ICA to remove artifacts, is it a good idea that the VEOG channel is excluded before run ICA ?<span> </span>The HEOG channel is placed on the tip of nose, and the VEOG channel is placed below the eyelid of the left eye.<u></u><u></u></span></font></p>
<p style="margin:0cm 0cm 0pt 18pt"><font size="4"><span lang="EN-US" style="font-family:'Times New Roman',serif"><span>2.<span style="font-style:normal;font-variant:normal;font-weight:normal;font-size:7pt;line-height:normal;font-family:'Times New Roman'"> </span></span></span><span lang="EN-US" style="font-family:'Times New Roman',serif"><span> </span>Before run ica, the continuous EEG data was segmented into stimulus-locked ERP epochs of 3000ms(-1000ms to 2000ms) and filtered at 1~30Hz. Is it necessary that the epochs is baseline corrected?<u></u><u></u></span></font></p>
<p style="margin:0cm 0cm 0pt 18pt"><font size="4"><span lang="EN-US" style="font-family:'Times New Roman',serif"><span>3.<span style="font-style:normal;font-variant:normal;font-weight:normal;font-size:7pt;line-height:normal;font-family:'Times New Roman'"> </span></span></span><span lang="EN-US" style="font-family:'Times New Roman',serif">When should I re-reference the channels to the channel on the tip of nose(i.e., the HEOG channel)? Before run ICA or after the independent components related to VEOG &HEOG is removed?<u></u><u></u></span></font></p>
<p style="margin:0cm 0cm 0pt 18pt"><font size="4"><span lang="EN-US" style="font-family:'Times New Roman',serif"><span>4.<span style="font-style:normal;font-variant:normal;font-weight:normal;font-size:7pt;line-height:normal;font-family:'Times New Roman'"> </span></span></span><span lang="EN-US" style="font-family:'Times New Roman',serif">How to efficiently identify the ICs that related to VEOG & HEOG. Is it a good idea to calculate the Pearson correlation coefficients between ICs and VEOG channel ? </span></font></p>
<p style="margin:0cm 0cm 0pt 18pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><u></u><font size="4"></font><u></u></span> </p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4">Any reply from you will be highly appreciated!<u></u><u></u></font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><u></u><font size="4"> </font><u></u></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4">Hui-bin Jia<u></u><u></u></font></span></p>
<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US" style="font-family:'Times New Roman',serif"><font size="4">Faculty of Psychology, Southwest University, China <u></u><u></u></font></span></p></div><br>_______________________________________________<br>
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