<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Stephan,<div><br></div><div>If I may ask, have you implemented this approach successfully in Fieldtrip? I agree that it can work well for auditory gamma, but have only done this in BESA. The minimumnormestimate.m function in FT is a time domain only technique as far as I know. If you have done this in Fieldtrip and can provide some guidance, I would very much appreciate the pointers.</div><div><br></div><div>Best,</div><div><br></div><div>Don</div><div><br></div><div><div><div>On Mar 8, 2013, at 12:51 AM, Stephan Moratti wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Nenad,<div><br></div><div>An alternative could be doing minimum norm on the real and imaginary part of your gamma response and then take the modulus get a measure of absolute power. This works for highly correlated sources see:</div><div><br></div><div><div style="margin: 0px; font-size: 19px; ">1.<span class="Apple-tab-span" style="white-space:pre"> </span>Jensen, O. & Vanni, S. A new method to identify multiple sources of oscillatory activity from magnetoencephalographic data. <i>Neuroimage </i><b>15</b>, 568-574 (2002).</div><div style="margin: 0px; font-size: 19px; "><br></div><div style="margin: 0px; font-size: 19px; ">It should also work for EEG and is easy to implement.</div><div style="margin: 0px; font-size: 19px; "><br></div><div style="margin: 0px; font-size: 19px; ">Best,</div><div style="margin: 0px; font-size: 19px; "><br></div><div style="margin: 0px; font-size: 19px; ">Stephan</div><div style="margin: 0px; font-size: 19px; "><br></div><div><div>El 08/03/2013, a las 02:16, Robert Oostenveld <<a href="mailto:r.oostenveld@donders.ru.nl">r.oostenveld@donders.ru.nl</a>> escribió:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi Nenad<br><br>On 7 Mar 2013, at 7:08, Nenad Polomac wrote:<br><blockquote type="cite">I would like to ask you for a suggestion about localisation o auditory evoked gamma osculations. I checked all tutorials and I haven't found much help. DICS beamformer doesn't work in this case. <br></blockquote><br><br>Please do note that the tutorials are not meant as a complete list of analyses that you can do, but they merely provide a practical starting point. Something not being listed on the fieldtrip wiki does not mean that it cannot be done. <br><br>One would not expect strong correlations/coherence between auditory activity in the gamma band, so beamforming is from a methodological viewpoint also not as problematic for high frequenies as it is for AEFs. This paper by Till Schneider (<a href="http://www.ncbi.nlm.nih.gov/pubmed/18617422">http://www.ncbi.nlm.nih.gov/pubmed/18617422</a>) demonstrates that with EEG beamforming of auditory gamma is possible. <br><br>If you fear for too strong correlations, you can try subsets of channels over both hemispheres. Or use a symmetric dipole pair (cfg.symmetric in ft_prepare_leadfield) as source model.<br><br>best regards,<br>Robert <br><br><br><br>_______________________________________________<br>fieldtrip mailing list<br><a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a><br><a href="http://mailman.science.ru.nl/mailman/listinfo/fieldtrip">http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a><br></blockquote></div><br><div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; "><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 style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><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 style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><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 style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><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 style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><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><br class="Apple-interchange-newline">________________________________________________________</div><div>Stephan Moratti, PhD<br><br></div><div>see also: <a href="http://web.me.com/smoratti/">http://web.me.com/smoratti/</a><br><br></div><div>Universidad Complutense de Madrid</div><div>Facultad de Psicología</div><div>Departamento de Psicología Básica I</div><div>Campus de Somosaguas</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain</div><div><br></div><div>and</div><div><br></div><div>Center for Biomedical Technology</div><div>Laboratory for Cognitive and Computational Neuroscience</div><div>Parque Científico y Tecnológico de la Universidad Politecnica de Madrid<br>Campus Montegancedo</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain<br><br><br>email: <a href="mailto:smoratti@psi.ucm.es">smoratti@psi.ucm.es</a><br>Tel.: +34 679219982<br><br></div></span></div></span></div></span></div></span></div></span></span>
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