<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
span.apple-tab-span
{mso-style-name:apple-tab-span;}
span.EstiloCorreo20
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:#1F497D;}
span.EstiloCorreo21
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:#1F497D;}
span.EstiloCorreo22
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 3.0cm 70.85pt 3.0cm;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>Dear Jan-Mathjis,<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>Thank you very much for your quick reply.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>I really appreciate your technical comment. I think that I had some confusion of some terms. I think the equation(15) refers the prior variance-covariance matrix of the source, which was set to be an identity matrix. Then it was estimated scalp covariance matrix taking into account this consideration (eq 16). Then Then it was reformulated the estimated ‘prior’ variance-covariance matrix (eq 17). I thought that the estimated ‘prior’ variance-covariance matrix should be identity matrix, but I found that this term in eq17 does not meet the criteria regardless of the hypothesis eq15. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>My question if the estimated ‘prior’ variance-covariance matrix in eq 17 should be identity matrix from theoretical point of view.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Best regards<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>*******************<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Yiyao Ye Lin</span><span lang=ES style='font-family:"Arial",sans-serif;color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>C/Camino de Vera SN<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Universidad Politècnica de València<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Departamento de Ingeniería Electrónica, Ed. 7F<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>46022, València<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>València<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Ext. 76026 <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>De:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> fieldtrip <<a href="mailto:fieldtrip-bounces@science.ru.nl">fieldtrip-bounces@science.ru.nl</a>> <b>En nombre de </b>Schoffelen, J.M. (Jan Mathijs) via fieldtrip<br><b>Enviado el:</b> martes, 11 de octubre de 2022 8:39<br><b>Para:</b> FieldTrip discussion list <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br><b>CC:</b> Schoffelen, J.M. (Jan Mathijs) <<a href="mailto:janmathijs.schoffelen@donders.ru.nl">janmathijs.schoffelen@donders.ru.nl</a>><br><b>Asunto:</b> Re: [FieldTrip] sloreta doest not get unity source variance<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Yiyao, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thank you for your attempts at clarifying your doubts. I still don’t understand what the confusion is. I doubt whether many people have made the effort of opening the word document, but I did so, and cannot make much out of it. It’s a bit too confusing to me to try and map all the different variable name conventions (paper versus code) onto each other. In general, however, I don’t understand why you think that the ’source covariance matrix’ should be an identity matrix, which source covariance matrix you are referring to, and which combination of variables in the code you would expect to yield an identity matrix. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>As in any distributed source model, the source reconstructed variance-covariance matrix (i.e. filter * C * filter’) surely will not be an identity matrix. This would namely imply that the variance of each of the reconstructed sources is the same (and has a value of 1). On the other hand, it could be that there’s some confusion with respect to the ‘prior’ that is used for the computations, i.e. the (implicit) identity matrix that is used for the computation of the Gram-matrix (lf * lf’) -> this can be thought of as (lf * S * lf’), with S being the prior variance-covariance matrix of the sources, which is often conveniently set to be an identity matrix. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Note that the FieldTrip code for the sloreta implementation has originally been contributed by Sarang Dalal, and this is based on the formulation as described in the Sekihara & Nagarajan book (adaptive spatial filters for electromagnetic brain imaging). It would therefore be better to check the code against the description in the book, rather than to the paper that you attached to the e-mail. And subsequently you might want to check the exposition in the book, with the paper.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Good luck and best wishes,<o:p></o:p></p></div><div><p class=MsoNormal>Jan-Mathijs<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>On 8 Oct 2022, at 16:56, Yiyao Ye Lin via fieldtrip <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Dear researchers,</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>I am sorry to not formulate correctly the question. In the attached file I attempted to explain my doubt. Hope that you can understand my question this time and can help me to better understand sLortea.<span class=apple-converted-space> </span></span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>What I can not understand is that sLoreta is standardized minimum norm solution, the source covariance matrix should be identity matrix. However, I could not check this. I think that there be something that I did not understand correctly.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Thank you very much for your attention</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Best regards</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>*******************</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Yiyao Ye Lin</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>C/Camino de Vera SN</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Universidad Politècnica de València</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Departamento de Ingeniería Electrónica, Ed. 7F</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>46022, València</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>València</span><o:p></o:p></p></div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Ext. 76026<span class=apple-converted-space> </span></span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> </span><o:p></o:p></p></div><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><div><p class=MsoNormal><b><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>De:</span></b><span class=apple-converted-space><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span></span><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>fieldtrip <<a href="mailto:fieldtrip-bounces@science.ru.nl">fieldtrip-bounces@science.ru.nl</a>><span class=apple-converted-space> </span><b>En nombre de<span class=apple-converted-space> </span></b>Schoffelen, J.M. (Jan Mathijs) via fieldtrip<br><b>Enviado el:</b><span class=apple-converted-space> </span>jueves, 6 de octubre de 2022 8:09<br><b>Para:</b><span class=apple-converted-space> </span>FieldTrip discussion list <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br><b>CC:</b><span class=apple-converted-space> </span>Schoffelen, J.M. (Jan Mathijs) <<a href="mailto:janmathijs.schoffelen@donders.ru.nl">janmathijs.schoffelen@donders.ru.nl</a>><br><b>Asunto:</b><span class=apple-converted-space> </span>Re: [FieldTrip] sloreta doest not get unity source variance</span><o:p></o:p></p></div></div></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Hi Yiyao,<span class=apple-converted-space> </span><o:p></o:p></p></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal>To be honest, I don’t understand your question. And it is not clear what the problem is. <o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal>Can you please have a look at the documentation below and reformulate your question, so that the readership of the list can constructively think along?<o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal><a href="https://www.fieldtriptoolbox.org/faq/how_to_ask_good_questions_to_the_community/"><span style='color:purple'>https://www.fieldtriptoolbox.org/faq/how_to_ask_good_questions_to_the_community/</span></a><o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal><a href="https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1002202"><span style='color:purple'>https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1002202</span></a><o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal><a href="http://www.catb.org/esr/faqs/smart-questions.html"><span style='color:purple'>http://www.catb.org/esr/faqs/smart-questions.html</span></a><o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal>Best wishes,<o:p></o:p></p></div></div><div><div><p class=MsoNormal>Jan-Mathijs<o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><br><br><o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal>On 5 Oct 2022, at 18:49, Yiyao Ye Lin via fieldtrip <<a href="mailto:fieldtrip@science.ru.nl"><span style='color:purple'>fieldtrip@science.ru.nl</span></a>> wrote:<o:p></o:p></p></div></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Dear researchers,</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>After reading the sLoreta theory, I attempted to understand the sloreta implementation detail. I attempted to obtain the source covariance matrix, and I could not get the expected unit variance. To do this, I attempted to calculate by two ways:</span><o:p></o:p></p></div></div><div style='margin-left:36.0pt'><div><p class=MsoNormal style='text-indent:-18.0pt'><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>a)</span><span style='font-size:7.0pt'> <span class=apple-converted-space> </span></span><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>lf'*invG*lf after line 268 of ft_inverse_sloreta</span><o:p></o:p></p></div></div><div style='margin-left:36.0pt'><div><p class=MsoNormal style='text-indent:-18.0pt'><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>b)</span><span style='font-size:7.0pt'> <span class=apple-converted-space> </span></span><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>lf(:,ii)'*invG*lf(:,ii) at line 267 of ft_inverse_sloreta</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>For this, I used EEG signal with average reference.<span class=apple-converted-space> </span></span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>What's wrong? How can the unity variance of source variance matrix?<span class=apple-converted-space> </span></span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Best regards</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>*******************</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Yiyao Ye Lin</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>C/Camino de Vera SN</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Universidad Politècnica de Valèn</span><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>cia</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Departamento de Ingeniería Electrónica, Ed. 7F</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>46022, València</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>València</span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Ext. 76026<span class=apple-converted-space> </span></span><o:p></o:p></p></div></div><div><div><p class=MsoNormal><span lang=ES style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span><o:p></o:p></p></div></div><div><p class=MsoNormal><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif'>_______________________________________________<br>fieldtrip mailing list<br></span><a href="https://mailman.science.ru.nl/mailman/listinfo/fieldtrip"><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:#954F72'>https://mailman.science.ru.nl/mailman/listinfo/fieldtrip</span></a><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif'><br></span><a href="https://doi.org/10.1371/journal.pcbi.1002202"><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:#954F72'>https://doi.org/10.1371/journal.pcbi.1002202</span></a><o:p></o:p></p></div></div></blockquote></div><div><p class=MsoNormal> <o:p></o:p></p></div></div><p class=MsoNormal><sloreta question.docx><sLoreta Technical details.pdf><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif'>_______________________________________________<br>fieldtrip mailing list<br></span><a href="https://mailman.science.ru.nl/mailman/listinfo/fieldtrip"><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:purple'>https://mailman.science.ru.nl/mailman/listinfo/fieldtrip</span></a><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif'><br></span><a href="https://doi.org/10.1371/journal.pcbi.1002202"><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:purple'>https://doi.org/10.1371/journal.pcbi.1002202</span></a><o:p></o:p></p></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>