Yes, I agree with Stefan,<div><br></div><div>Also I have some other comments: You better not include particularly M1, M2, inferior-ocular (below the eye) VEOG in the ICA. This is mainly because of the fact that they are not really very relevant/informative/strong for the cognitive based ICAs. Inf-Ocular is very noisy most of the cases and M1 and M2 have very small potential and small representative power.</div>
<div><br></div><div>So such electrodes are "distortions" for the ICA: they make ICA baffle. Do you still really want to include the other EOG electrodes? Then maybe just include Supraocular VEOG (above the eye) and maybe the HEOGs (if possible include both right and left sides because they are not showing symmetrical activities: When you move your eye to the right, right HEOG gets peaky positive and the left HEOG becomes slow-drifty negative). </div>
<div><br></div><div>But even for the detection of the artifact related ICAs you still can do without the VEOG and HEOG just by looking at the ICA components over the edgy AF8, AF10 electrodes etc. I suppose many ICA based correction algorithms do not need these electrodes. But some programs (like Analyzer2) also asks VEOG and HEOG though, maybe for better use of these activities in a particular algorithm. I do not personally include these electrodes in my ICA based corrections or ICA decompositions. I only use them maybe for classical artifact rejection over epochs if I need to.</div>
<div> </div><div>Baris<br><br><div class="gmail_quote">2011/3/24 Stefan Debener <span dir="ltr"><<a href="mailto:stefan.debener@uni-oldenburg.de">stefan.debener@uni-oldenburg.de</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div text="#000000" bgcolor="#ffffff">
Dear Iren,<br>
<br>
It is difficult to evaluate the quality of a single IC without
further information. How do the other ICs look like? Do you find
many dipolar ICs, and reasonable artefact ICs? If not I would
suspect that the overall quality of the decomposition is rather
poor. Consider HP filtering and pruning your data first (see EEGLAB
tutorial).<br>
Also, are you sure you have the correct electrodes location file? It
seems you have recorded against the left mastoid. The plot suggest
one left lateral HEOG and one right inferior VEOG channel. We prefer
not using bioloar recordings anymore, recording all your data
against a common reference is usually easier (to collect and later
process) and reveals basically the same amount of information. The
evaluation of topographies is also complicated by a mixture of
unipolar and bipolar channels, so this could explain some prominent
features of the map you are showing.<br>
<br>
Best,<br>
Stefan<br>
<br>
<br>
Am 3/22/11 3:03 PM, schrieb Barkaszi Irén:
<blockquote type="cite"><div><div></div><div class="h5">
Dear all,<br>
<br>
I got an uninterpretable component in my analysis.<span> This component's </span>scalp map is very<span> </span>diffuse and the source dipole is outside the
brain. I would like to quantify the component's quality with a
single equivalent current dipole but it would entail the
elimination of the component, though its ERP contributes strongly
to the data ERP. Do you think it is correct to throw it out?<span><br>
Please find enclosed a figure about this component.<br>
</span>
<p class="MsoNormal"><span>Thank you in advance,<br>
Iren<br>
</span></p>
<br>
</div></div><pre><fieldset></fieldset>
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<pre cols="72">--
Prof. Dr. Stefan Debener
Neuropsychology Lab
Department of Psychology
University of Oldenburg
D-26111 Oldenburg
Germany
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