<a href="http://link.springer.com/article/10.1007/s10548-012-0274-6/fulltext.html">This recent paper</a> by Zeynep Akalin Acar finds that mis-specification of the skull conductivity ratio (versus scalp or brain) may drive the equivalent dipoles deeper than they actually are. This is a variable for which there is currently no easy/best method of measurement. Therefore, the radial depth of equivalent dipole localizations may be their least well-defined dimension. Before accepting a thalamic localization for an equivalent dipole, I would want to thoroughly test the influence of the head model being used on the depth of the imputed source location.<div>
<br></div><div>Scott<br><br><div class="gmail_quote">On Thu, Mar 28, 2013 at 2:14 AM, Arnaud Delorme <span dir="ltr"><<a href="mailto:arno@ucsd.edu" target="_blank">arno@ucsd.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word"><div>Dear Aleksandra,</div><div><br></div>the Thalamus as all subcortical structure most likely has a minor effect on scalp EEG (because it is a node, if all neurons are active at the same time, their net potential is null). A perfect spherical domain of synchrony cannot be seen on the scalp.<div>
<br></div><div>Now the interaction between the thalamus and the cortex is what might be seen. I guess it would be seen as ICA components with a cortical location.</div><div><br></div><div>Best,</div><div><br></div><div>Arno</div>
<div><div class="h5"><div><div><div><br><div><div>On 22 Mar 2013, at 17:48, Makoto Miyakoshi wrote:</div><br><blockquote type="cite">Dear Aleksandra and Tom,<div><br></div><div><span style="font-family:Tahoma;font-size:x-small">> However Tom's email indicates that the source analysis model used in EEG lab is not adequate for localising</span><a style="font-family:Tahoma;font-size:x-small"></a><span style="font-family:Tahoma;font-size:x-small"> sources in deeper structures, or I got it wrong?</span><br>
<br>My naive thought is that thalamus is involved in alpha rhythm but that does not mean it project it to the scalp. It is one of nodes of network that drives the occipital cortical patches to oscillate in alpha. Let me know if you find more information about it.</div>
<div><br></div><div>Tom's input is informative as usual. Thanks.</div><div><br></div><div>Makoto<br><br><div class="gmail_quote">2013/3/19 Aleksandra Vuckovic <span dir="ltr"><<a href="mailto:Aleksandra.Vuckovic@glasgow.ac.uk" target="_blank">Aleksandra.Vuckovic@glasgow.ac.uk</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>My modest understanding is that thalamus generates rhythmic<a></a> oscillatory<a></a> activity<a></a> and is one of the generators of the alpha rhythm<a></a>. I taught therefore that it should not be surprising<a></a> that some ICs are located in thalamus.
However Tom's email indicates that the source analysis model used in EEG lab is not adequate for localising<a></a> sources in deeper structures, or I got it wrong?</div>
<div><font face="tahoma">Thanks,</font></div>
<div><font face="tahoma">Aleksandra</font></div>
<div dir="ltr"><font color="#000000" face="Tahoma"></font> </div>
<div style="DIRECTION:ltr">
<hr>
<font color="#000000" face="Tahoma"><b>From:</b> Makoto Miyakoshi [<a href="mailto:mmiyakoshi@ucsd.edu" target="_blank">mmiyakoshi@ucsd.edu</a>]<br>
<b>Sent:</b> 19 March 2013 17:14<br>
<b>To:</b> Aleksandra Vuckovic<br>
<b>Cc:</b> EEGLAB List<div><div><br>
<b>Subject:</b> Re: [Eeglablist] Different clusters within thalamus?<br>
</div></div></font><br>
</div><div><div>
<div></div>
<div>Dear Aleksandra,
<div><br>
</div>
<div><span style="FONT-FAMILY:tahoma;FONT-SIZE:x-small">>Even some that I see consistently across</span><a style="FONT-FAMILY:tahoma;FONT-SIZE:x-small"></a><span style="FONT-FAMILY:tahoma;FONT-SIZE:x-small"> subjects?</span><br>
<br>
Consistency across subjects does not increase the possibility that the ICs are really located in or near thalamus, unless you are using the combination of digitized channel locations, subject's MRI head image, and Zeynep Akalin Acar's NFT...</div>
<div><br>
</div>
<div>To generate a dipole, neuron arrays should have a specific pattern. I'm not sure if thalamus also has this pattern. It's a matter of cytoarchitecture, so you may want to read papers about electrophysiological mechanism of generating EEG. I don't know much
about it, so if you find something interesting please share with us. </div>
<div><br>
</div>
<div>Makoto</div>
<div><br>
<div class="gmail_quote">2013/3/19 Aleksandra Vuckovic <span dir="ltr"><<a href="mailto:Aleksandra.Vuckovic@glasgow.ac.uk" target="_blank">Aleksandra.Vuckovic@glasgow.ac.uk</a>></span><br>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex" class="gmail_quote">
<div>
<div style="FONT-FAMILY:Tahoma;DIRECTION:ltr;FONT-SIZE:x-small">
<div>Hi</div>
<div><font face="tahoma">does it mean that these sources are not of a physiological origin (EEG related)? Even some that I see consistently across<a></a> subjects?</font></div>
<div><font face="tahoma">Many thanks,</font></div>
<div><font face="tahoma">Aleksandra</font></div>
<div dir="ltr"><font color="#000000" face="Tahoma"></font> </div>
<div style="DIRECTION:ltr">
<hr>
<font color="#000000" face="Tahoma"><b>From:</b> Makoto Miyakoshi [<a href="mailto:mmiyakoshi@ucsd.edu" target="_blank">mmiyakoshi@ucsd.edu</a>]<br>
<b>Sent:</b> 19 March 2013 00:27<br>
<b>To:</b> Aleksandra Vuckovic<br>
<b>Cc:</b> <a href="mailto:eeglablist@sccn.ucsd.edu" target="_blank">eeglablist@sccn.ucsd.edu</a><br>
<b>Subject:</b> Re: [Eeglablist] Different clusters within thalamus?<br>
</font><br>
</div>
<div>
<div>
<div></div>
<div>Dear Aleksandra,
<div><br>
</div>
<div>Independent components located in or near thalamus should be mostly due to localisation error in dipole fitting (forward model error/inverse solution error/channel location error/...etc). We see it often though :-)</div>
<div><br>
</div>
<div>Makoto</div>
<div><br>
<div class="gmail_quote">2013/3/16 Aleksandra Vuckovic <span dir="ltr"><<a href="mailto:Aleksandra.Vuckovic@glasgow.ac.uk" target="_blank">Aleksandra.Vuckovic@glasgow.ac.uk</a>></span><br>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex" class="gmail_quote">
<div>
<div style="FONT-FAMILY:Tahoma;DIRECTION:ltr;FONT-SIZE:x-small">
<div></div>
<div dir="ltr"><font color="#000000" face="Tahoma">Hi</font></div>
<div dir="ltr"><font face="tahoma">has anybody tried to cluster components at different locations within thalamus and according<a></a> to which criteria?</font></div>
<div dir="ltr"><font face="tahoma">Many thanks!</font></div>
<span><font color="#888888">
<div dir="ltr"><font face="tahoma">Aleksandra</font></div>
</font></span></div>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br>Makoto Miyakoshi<br>JSPS Postdoctral Fellow for Research Abroad<br>Swartz Center for Computational Neuroscience<br>Institute for Neural Computation, University of California San Diego<br>
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