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Dear Myrto,
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<div class="">I think that what you ask is ‘how do I create a (set of) virtual channel(s)?’</div>
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<div class="">There is no dedicated documentation for this yet. First of all, I think that you need to look into source reconstruction. After computing the forward model (a.k.a. as the leadfields) you need to use this in order to ’source reconstruct’ the channel
level data, using some sourceanalysis method. More precisely, you need to compute an 'inverse operator’ which can be used to left multiply your sensor data with, in order to obtain single epoch time course of the ‘virtual channels’.</div>
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<div class="">The virtual channels can be computed using the ft_virtualchannel function. Yet, in order to be able to use this, you need to use ft_sourceanalysis first.</div>
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<div class="">Best wishes,</div>
<div class="">Jan-Mathijs</div>
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<div class="">On 9 Jun 2021, at 16:38, Myrto Mantziara via fieldtrip <<a href="mailto:fieldtrip@science.ru.nl" class="">fieldtrip@science.ru.nl</a>> wrote:</div>
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<span lang="EN-US" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;" class="">Dear Fieldtrip Team,</span><span lang="EN-US" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;" class=""><span class="Apple-converted-space"> </span><br class="">
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<span lang="EN-US" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; line-height: normal;" class=""><br class="">
</span></o:p></span></p>
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<span style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class="">I would like to extract epoched EEG data from dipole sources in a Region of Interest (ROI). For the forward solution in the source analysis, I reconstructed the sources using
the standard BEM headmodel (found in the Fieldtrip directory: fieldtrip-20160814\template\headmodel\standard_bem.mat) and computed the leadfield. Now I would like to apply the dipole leadfield weights to extract epoched time-series from dipoles of interest,
e.g., all dipoles located in the primary motor cortex. In other words, I would like to examine the epoched data in source space (amplitude for each dipole for MVPA analysis, and time-frequency data averaged across the ROI).</span><span style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class=""><span class="Apple-converted-space"> </span></span></o:p>Also,
we are not sure which leadfield weight to include (dipole orientations).<span class="Apple-converted-space"> </span><br class="">
</span></div>
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<span style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class="">Last, do you have a function that does such weighting correctly to achieve orthogonalization in the contribution of other sources (e.g., nearby to the ROI sources) in order
to increase specificity.</span><span style="font-size: 10.5pt; font-family: "Segoe UI", sans-serif;" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class=""> </span></o:p></span></div>
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<span style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class="">Perhaps there is an example code or other functions which I have not come across.<span class="Apple-converted-space"> </span><br class="">
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<span style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class="">We would appreciate your help.</span><span style="font-size: 10.5pt; font-family: "Segoe UI", sans-serif;" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class=""><span class="Apple-converted-space"> </span><br class="">
</span></o:p></span></div>
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</span></o:p></span></div>
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</span></o:p></span></div>
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<span lang="EN-US" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class="">Regards,</span><span lang="EN-US" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class=""> </span></o:p></span></p>
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<span lang="EN-US" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class="">Myrto Mantziara</span><span lang="EN-US" class=""><o:p class=""><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;" class=""> </span></o:p></span></p>
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<span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">Myrto Mantziara</span></div>
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<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">PhD Candidate</span></div>
<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">School of Psychology</span></div>
<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">Bangor University</span></div>
<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">United Kingdom</span></div>
<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">Email:<span class="Apple-converted-space"> </span><a href="mailto:m.mantziara@bangor.ac.uk" class="">m.mantziara@bangor.ac.uk</a></span></div>
<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">Lab Website:<span class="Apple-converted-space"> </span><a href="http://sites.google.com/site/kkornysheva/" class="">sites.google.com/site/kkornysheva/</a></span></div>
<div class=""><span style="font-size: 11pt; font-family: "Calibri Light", "Helvetica Light", sans-serif;" class="">School Social Media:<span class="Apple-converted-space"> </span><a href="https://urldefense.com/v3/__https://www.bangor.ac.uk/psychology/social-media.php.en__;!!HJOPV4FYYWzcc1jazlU!spdDU_sPLbu4E_re5ebsxhNIUhlA9vNHlfEoKCqwt9swcj-gpRkjHNMCMdLhTV_S1dNdkGfA$" class="">https://www.bangor.ac.uk/psychology/social-media.php.en</a></span></div>
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