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<p>Dear Laurent:</p>
<p>
<blockquote type="cite">So the question is : if I am happy with
the result of a 2 + 1 montage by using CP3 and P5 (at -1 mA) and
P1 (at +2mA) with PI electrodes in a tDCS perspective...how to
translate this in terms of tACS parameters ?</blockquote>
</p>
<p>Opposite signs in TDCS translate to a 180° phase shift in TACS.
So here you will have currents with the opposite phase in P1
versus CP3 and P5. I suggest that you look at the normal component
of E on the cortex (see also
<a class="moz-txt-link-freetext" href="https://simnibs.github.io/simnibs/build/html/faq.html">https://simnibs.github.io/simnibs/build/html/faq.html</a> for an
explanation fo the normal component): All positions that have
opposite signs have a 180° phase shift to each other. You can tell
Simnibs to calculate the normal component in the simulation
options.</p>
<p>For more details, please see also
<a class="moz-txt-link-freetext" href="https://www.biorxiv.org/content/10.1101/500314v1">https://www.biorxiv.org/content/10.1101/500314v1</a> and
<a class="moz-txt-link-freetext" href="https://pubmed.ncbi.nlm.nih.gov/28919407/">https://pubmed.ncbi.nlm.nih.gov/28919407/</a><br>
</p>
<p>Best regards,</p>
<p>Axel</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 9/17/2020 3:36 PM, LAURENT TORLAY
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:586040752.55784415.1600349791180.JavaMail.zimbra@univ-grenoble-alpes.fr">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div style="font-family: arial, helvetica, sans-serif; font-size:
12pt; color: #000000">
<div>Hi,<br>
</div>
<div>Thank you fo developping SimNibs software !<br>
I have a newbie question about tACS (I already did tDCS
simulations and experiments).<br>
First, I use Neuroelectrics (NE) device and, with their
software, I have the possibility to have several "input"
electrodes with different phases and only one return electrode
if needed.<br>
In Simnibs, the GUI is designed fo tDCS but I understood that
the results can be extrapolated to tACS for low frequencies
(that's our case : around 10 Hz).<br data-mce-bogus="1">
</div>
<div>So the question is : if I am happy with the result of a 2 +
1 montage by using CP3 and P5 (at -1 mA) and P1 (at +2mA) with
PI electrodes in a tDCS perspective...how to translate this in
terms of tACS parameters ?<br>
For example, can I manage this with phase difference but with
same amplitude or half ? What is exactly the role of return
electrodes in tACS ?<br>
Thanks in advance,<br>
</div>
<div>Laurent<span style="font-size:10pt"></span></div>
</div>
<br>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
Dr. Axel Thielscher
Associate Professor
Danish Research Center for Magnetic Resonance
Copenhagen University Hospital Hvidovre
DK-2650 Hvidovre, Denmark
<a class="moz-txt-link-abbreviated" href="http://www.drcmr.dk">www.drcmr.dk</a>
&
Department of Health Technology
Technical University of Denmark
DK-2800 Kgs. Lyngby
<a class="moz-txt-link-freetext" href="http://www.healthtech.dtu.dk/">http://www.healthtech.dtu.dk/</a></pre>
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