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Hi Min-Young,
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<div class="">Did you check the original paper that is referenced in the code? I suggest to start there.</div>
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<div class="">Also, re-referencing to the average is achieved by <b class="">subtraction</b> of the mean over channels, i.e. : data - mean(data)</div>
<div class="">The line you refer to is <b class="">adding</b> the mean of some variable (data_z) to data, which is not average rereferencing.</div>
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<div class="">Best wishes,</div>
<div class="">Jan-Mathijs</div>
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<blockquote type="cite" class="">
<div class="">On 21 Oct 2020, at 04:06, Min-Young Kim <<a href="mailto:mykim@kriss.re.kr" class="">mykim@kriss.re.kr</a>> wrote:</div>
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<span lang="EN-US" class="">Dear FieldTrippers,<o:p class=""></o:p></span></div>
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<span lang="EN-US" class=""><o:p class=""> </o:p></span></div>
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<span lang="EN-US" class="">I am working with 19 Ch EEG data acquired with Biosemi system. To test re-reference options, I tried average earlobes, common average, and REST methods in the preprocessing. However, I found that the EEG for REST was almost the same
as the EEG for common average. When I looked at the ft_preproc_rereference.m, the line 141 says<span class="Apple-converted-space"> </span><o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">>>data_z = G * pinv(Gar, 0.05) * data;<o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">But then in line 144<o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">>>data_z = data + repmat(mean(data_z), size(G,1), 1);<o:p class=""></o:p></span></div>
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<span lang="EN-US" class=""><o:p class=""> </o:p></span></div>
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<span lang="EN-US" class="">Isn’t the line 141 enough to generate REST EEG signals? To me, the line 144 seems to be the common average referenced EEG data. I would appreciate if someone explains the meaning of the line 144.<o:p class=""></o:p></span></div>
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<span lang="EN-US" class=""><o:p class=""> </o:p></span></div>
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<span lang="EN-US" class="">Thanks,<o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">Min-Young<o:p class=""></o:p></span></div>
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<span lang="EN-US" class=""><o:p class=""> </o:p></span></div>
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<span lang="EN-US" class="">Min-Young Kim, Ph.D.<o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">Tel: +82) 42 - 868 - 5204 (Office)<o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">Email:<span class="Apple-converted-space"> </span><a href="mailto:mykim@kriss.re.kr" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">mykim@kriss.re.kr</a><o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">Quantum Technology Institute<o:p class=""></o:p></span></div>
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<span lang="EN-US" class="">Korea Research Institute of Standards and Science<o:p class=""></o:p></span></div>
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<span lang="EN-US" class=""><o:p class=""> </o:p></span></div>
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<a href="https://doi.org/10.1371/journal.pcbi.1002202" style="color: rgb(149, 79, 114); text-decoration: underline; font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://doi.org/10.1371/journal.pcbi.1002202</a></div>
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