<html><head><base href="x-msg://572/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Igor,<div><br></div><div>we fit 95%-99% of the components using a single equivalent dipole. We only fit 2 symmetrical dipoles for bilateral occipital alpha ICA components which are easily recognizable. Note that a large number of components cannot be fitted well with a single dipole (or 2 bilateral dipoles). These include artifactual components, or components that do not account for much of the data variance and reflect noise in the EEG data or in the ICA algorithm optimization procedure.</div><div><br></div><div>Best regards,</div><div><br></div><div>Arno</div><div><br><div><div>On May 27, 2011, at 6:06 AM, Igor Riecansky wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div lang="EN-US" link="blue" vlink="purple"><div class="Section1" style="page: Section1; "><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Dear EEGLAB community,<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">I am starting to use DIPFIT2 to localize brain sources of PCA/ICA EEG components. I face a problem to decide how many dipoles to fit, i.e. one unilateral vs two bilateral symmetrical. Some papers simply always assume 2 symmetrical sources. However, if component's topography is highly asymmetric, this seems not to be justified. Furthermore, in case of a symmetric topography one could often reasonably assume both one unilateral or two bilateral sources both originating from brain structures close to the midline. Of course, solutions may substantially differ for one and two sources. What is you experience and practice? How do you solve this problem? Do you use any quantitative test? Residual variance is always lower when two sources are fitted compared to one source. Is there some rule to consider this reduction as significant, or can the reduction of residual variance be statistically tested?<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">I will greatly appreciate any feedback and help. Thanks.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Igor<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">-----------------------------<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">Igor Riecansky, MD PhD<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">SCAN-Unit<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">Institute of Clinical, Biological and Differential Psychology<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">Faculty of Psychology<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">University of Vienna<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">Liebiggasse 5, A-1010 Austria<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">Tel.: +43-1-4277-47 509<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 9pt; ">Room No.<span class="Apple-converted-space"> </span></span><span lang="DE" style="font-size: 9pt; ">O3.28<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="DE" style="font-size: 9pt; ">E-mail:<span class="Apple-converted-space"> </span><a href="mailto:igor.riecansky@univie.ac.at" style="color: blue; text-decoration: underline; ">igor.riecansky@univie.ac.at</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="DE"><o:p> </o:p></span></div></div>_______________________________________________<br>Eeglablist page:<span class="Apple-converted-space"> </span><a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" style="color: blue; text-decoration: underline; ">http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br>To unsubscribe, send an empty email to<span class="Apple-converted-space"> </span><a href="mailto:eeglablist-unsubscribe@sccn.ucsd.edu" style="color: blue; text-decoration: underline; ">eeglablist-unsubscribe@sccn.ucsd.edu</a><br>For digest mode, send an email with the subject "set digest mime" to<span class="Apple-converted-space"> </span><a href="mailto:eeglablist-request@sccn.ucsd.edu" style="color: blue; text-decoration: underline; ">eeglablist-request@sccn.ucsd.edu</a></div></span></blockquote></div><br></div></body></html>