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<p>Dear FieldTrippers</p>
<p>I know this is not a usual topic but maybe you can give me some advice, I would like to ask you some help for the correction of ocular artifacts on facial thermal imaging signals. The temperature of the periorbital areas is very informative about the sympathetic system activity, but we realized that blinks and saccades also influence the temperature in these regions</p>
<p>Our signal is sampled at 10 Hz and the time course is extracted from 10 regions of interest, one of which is placed exactly on the right eye. Thus we have 10 channels (ROIs).</p>
<p>We preprocessed the signal by using a band pass filter (Butt 0.01 - 4 Hz) and by demeaning it.</p>
<p>Then we used ICA (runica or fastica) to detect the ocular components. A component was defined as “artefactual ocular” when its face distribution was mostly around the eye and the periorbital channels.</p>
<p>After subtracting that component from the original signal, we saw that the signal was very well corrected on the eye channel itself but it got worst in the channel of interest (the periorbitals) by introducing some artefacts. Further we noticed that the unmixing matrix was close to singular (det(A) = 10^-13).</p>
<p>We thought that this could be due to the number of channels so we also tried to export more (64) ROIs but nothing changed.</p>
<p>Do you have any idea about why this would happen? We thought that ICA could work on any type of wave, but maybe there is something we are missing.</p>
<p>Should we use another method? Do you have any suggestion?</p>
<p>Any suggestion is pretty much appreciated</p>
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<p>Thanks in advance for any help.</p>
<p>Giulia</p>
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