<div dir="ltr">Dear Pete,<div><br></div><div>In my experience, multiplying 0.7893 to polar radius worked (that does not mean I correct it all the time; I don&#39;t care :-). Try this code and compare topomaps. Don&#39;t forget to apply &#39;optimize center&#39; before doing it (this button is on the right top of channel edit window).</div>

<div><br></div><div>%%%%%%%%%%%</div><div><span style="font-family:arial,sans-serif">    for n=1:length(EEG.chanlocs)</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">        EEG.chanlocs(1,n).</span><span class="" style="font-family:arial,sans-serif">radius</span><span style="font-family:arial,sans-serif"> = EEG.chanlocs(1,n).</span><span class="" style="font-family:arial,sans-serif">radius</span><span style="font-family:arial,sans-serif">*0.</span><span style="font-family:arial,sans-serif">7893</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">    end</span><br></div><div class="gmail_extra">%%%%%%%%%%%<br><br>There was a big discussion in SCCN what the head &#39;circle&#39; in the topoplot should represent... generally speaking, any channels located lower than the circumference that connects Nz-eye-earholes/auriculars-Iz should show outside the circle (i.e. &#39;skirt&#39;). Note that this &#39;interpretation&#39; stands on the assumption that the circle = Nz-eye-earholes/auriculars-Iz line. Probably, the current EEGLAB&#39;s 2D headplot is slightly more inflated than this definition.</div>

<div class="gmail_extra"><br></div><div class="gmail_extra">FYI the citation below is from <span style="font-family:arial,sans-serif">Oostenveld and Praamstra (2001) p.714.</span></div><div class="gmail_extra"><span style="font-family:arial,sans-serif">%%%%%%%%%%%</span></div>

<div class="gmail_extra"><span style="font-family:arial,sans-serif">The placement of electrodes is based on landmarks on the skull,</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">namely the nasion (Nz), the inion (Iz), and the left and right</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">pre-auricular points (LPA and RPA). The first step is to form the line</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">from Nz to Iz, approximately over the vertex. To determine the</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">location of the vertex, the contour from LPA to RPA is also passed</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">over the vertex. These two contours should intersect at 50% of their</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">lengths and the point thus obtained is the exact vertex.  Along the</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">sagittal Nz-Iz scalp contour over the vertex, the positions Fpz, AFz,</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">Fz, FCz, Cz, CPz, Pz, POz and Oz are</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">marked at 10% distances along this antero-posterior contour (Fig. 1).</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">With position Cz at 50% along this contour, corresponding</span><br style="font-family:arial,sans-serif"><span style="font-family:arial,sans-serif">to the vertex, the position of Oz is at a distance of 90% from Nz and</span><br style="font-family:arial,sans-serif">

<span style="font-family:arial,sans-serif">10% from Iz.</span><span style="font-family:arial,sans-serif"><br></span></div><div class="gmail_extra"><span style="font-family:arial,sans-serif">%%%%%%%%%%%%</span></div><div class="gmail_extra">

<br></div><div class="gmail_extra">Makoto<br><br><div class="gmail_quote">2014/1/5 Pete Manza <span dir="ltr">&lt;<a href="mailto:pete.manza@gmail.com" target="_blank">pete.manza@gmail.com</a>&gt;</span><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 dir="ltr">Hello,<div><br></div><div>I&#39;ve tried to search the listserv but can&#39;t seem to find the answer to this - I&#39;ve been trying to use topoplot to generate scalp maps for publication (I have a standard 64-electrode montage). However I can&#39;t seem to get the electrodes/topography neatly inside the outline of the head. </div>



<div><br></div><div>I&#39;ve tried messing with the &quot;plotrad&quot; and &quot;headrad&quot; options, but it doesn&#39;t come out well and I know that in doing so I&#39;m making the image anatomically incorrect. </div>



<div><br></div><div>So, is there a way to make the image look neat and &quot;bend&quot; the electrodes inside the head radius?<br><br></div><div>It would be nice to get it to look something like figure 4 here: <br><a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114253/" target="_blank">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114253/</a><br>


<br></div><div>Thanks so much!<span class=""><font color="#888888"><br></font></span></div><span class=""><font color="#888888"><div>Pete<br></div></font></span></div>
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-- <br><div dir="ltr">Makoto Miyakoshi<br>Swartz Center for Computational Neuroscience<br>Institute for Neural Computation, University of California San Diego<br></div>
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