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<div class="moz-cite-prefix">I think the assumption is that if brain
A is 10% larger than brain B then the cortical region normally
associated with C3 is 10% further from the midline in brain A than
it is in brain B. Thus, if you are using differently-sized caps
(with different electrode spacing) for differently-sized heads
then you may assume that C3 from subject A represents
approximately the same patch of brain as C3 from subject B. The
precise coordinates of C3 don't matter.<br>
<br>
Of course the above assumption is false not only because the head
shapes vary but also because the relative skull conductance and
brain curvatures vary. While having super-accurate coordinates
might help overcome the problem of head shape, it won't help with
the other problems. If you have anatomical MR images for each
subject and you are able to coregister your electrode positions
with the MRI then you may be able to use ICA+NFT+DIPFIT to
identify subject-specific neurobiological 'sources'. You may then
use some component-clustering algorithm to figure out which
component from each subject represents a particular patch of brain
then do your between subject/group comparisons on those
components' activations. (Notice that I skipped over the
skull-conductance problem.)<br>
<br>
If you need to identify precise (not necessarily accurate) brain
regions associated with your task then the above method might be
for you. However, if you REALLY need to identify brain sources
accurately then you might be better off going with fMRI or
EEG-fMRI if time-resolution is important.<br>
<br>
If you don't need to report specific brain regions then I'd just
stick with averaging across electrodes with the same name.<br>
<br>
On 2/20/2013 9:47 AM, Iman M.Rezazadeh wrote:<br>
</div>
<blockquote cite="mid:00e501ce0f03$d0364860$70a2d920$@ucdavis.edu"
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<p class="MsoNormal">Dear all,<o:p></o:p></p>
<p class="MsoNormal">Since each subject has its own head
diameter thus electrode placement over the head might be
slightly different ! <o:p></o:p></p>
<p class="MsoNormal">Thus, do you have any idea how to
standardize the electrode configuration from different
subjects for within or btw group comparison! <o:p></o:p></p>
<p class="MsoNormal">I am using spline interpolation to convert
my 128 channel data to 81 channel. However the new coordinates
are still slightly different from subject to subject!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any thought??? <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">Iman
M.Rezazadeh, PhD<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">Postdoctoral
Research Fellow<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">Center
for Mind and Brain<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">University
of California, Davis<o:p></o:p></span></p>
<p class="MsoNormal"><a moz-do-not-send="true"
name="webProfileURL"></a><a moz-do-not-send="true"
href="http://www.linkedin.com/pub/iman-m-rezazadeh/10/859/840"
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style="font-size:8.0pt;font-family:"Arial","sans-serif";color:#1F497D;border:none
windowtext 1.0pt;padding:0in;background:#F6F6F6">www.linkedin.com/pub/iman-m-rezazadeh/10/859/840</span></a><span
style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://mindbrain.ucdavis.edu/people/imanmr"><span
style="font-family:"Arial","sans-serif";color:#1F497D">http://mindbrain.ucdavis.edu/people/imanmr</span></a><span
style="font-family:"Arial","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">email
: </span><a moz-do-not-send="true"
href="mailto:irezazadeh@ucdavis.edu"><span
style="font-family:"Arial","sans-serif";color:#1F497D">irezazadeh@ucdavis.edu</span></a><span
style="font-family:"Arial","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">Tel:
530-297-4444<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">Cell:310-490-1808<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:#1F497D">Skype:
Imanmr<o:p></o:p></span></p>
<p class="MsoNormal"><span dir="RTL"
style="font-size:8.0pt;font-family:"Arial","sans-serif";color:#1F497D;mso-fareast-language:ZH-TW"
lang="FA">ایمان محمد رضازاده</span><span
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<p class="MsoNormal"><span
style="font-size:8.0pt;font-family:"PMingLiU","serif";color:#1F497D;mso-fareast-language:ZH-TW"
lang="ZH-TW">伊芒</span><b><span
style="font-size:8.0pt;color:#1F497D">·</span></b><span
style="font-size:8.0pt;font-family:"MS
Mincho";color:#1F497D">瑞扎扎德<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:8.0pt;font-family:"MS
Mincho";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
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<p class="MsoNormal"><span
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