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<p>Hi,</p>
<p>you can easily calculate the fields created by any combination of
electrode currents using a linear combination of the lead fields.
The only constraint is that electrode currents sum up to zero. The
leadfields are all calcuated relative to a common reference
electrode for a unit current. The field between, e.g. for a
current flow of 2 mA between electrodes 1 and 2 is then:</p>
<p>EF(El2 to El1, 2mA) = 2mA*( EF(El2 to El_ref) - EF(El1 to El_ref)
) = 2mA*(leadfield_El2 - leadfield_El1).</p>
<p>Hope this helps.<br>
</p>
<p>Best,</p>
<p>Axel<br>
</p>
<div class="moz-cite-prefix">On 14-04-2022 17:15, Jaimie Jobson
(jj3g17) wrote:<br>
</div>
<blockquote type="cite"
cite="mid:LNXP265MB088949AF318A12C9180DBF59DDEF9@LNXP265MB0889.GBRP265.PROD.OUTLOOK.COM">
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hello,</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’m an Msc student working on creating a
neural network that is capable of predicting the magnitude of
electric field at a given position/positions in the brain
(tDCS). For this I’m using a 19 electrode cap. I need to be
able to quickly and automatically find the electric field at a
given position for a large combination of electrodes and
positions. For example to predict the e field at a position
created when two electrodes are switched on from the 19
electrode cap. However to accomplish this I need to be able to
simulate hundreds if not thousands of combinations (depending
on how many electrodes are switched on). Doing this by
undertaking thousands of simulation would be extremely time
consuming, however from my understanding I could very quickly
find the E field at certain positions for many hundreds of
electrode combinations by using the Lead-field of a head
model. All information related to Lead-fields refers to
optimization, however can it be used to predict the outcome of
many simulations. If so how would I go about programming this.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Jaimie Jobson<o:p></o:p></p>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
Dr. Axel Thielscher
Professor of Neurophysics and Neuroimaging
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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