<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=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:"\@SimSun";
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-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.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0cm;
margin-right:0cm;
margin-bottom:0cm;
margin-left:36.0pt;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
span.StileMessaggioDiPostaElettronica17
{mso-style-type:personal-compose;
font-family:"Verdana","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 2.0cm 2.0cm 2.0cm;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:2032993851;
mso-list-type:hybrid;
mso-list-template-ids:2024602352 68157455 68157465 68157467 68157455 68157465 68157467 68157455 68157465 68157467;}
@list l0:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level2
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level3
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level4
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level5
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level6
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level7
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level8
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;}
@list l0:level9
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
ol
{margin-bottom:0cm;}
ul
{margin-bottom:0cm;}
--></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=IT link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Dear all,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>I’m performing an ICA followed by a dipole source localization (DIPFIT) and I’m not satisfied by the outcome of the analysis because it returns too high values of residual variance (RV%).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Here the details of the EEG signal acquisition and processing (eeglab v13.6.5b):<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Data acquisition with EGI (srate = 500 Hz; 129 channel): <o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>two blocks of an execution task (EX) + two blocks of motor imagery task (IM) (overall, around 17 minutes of recording)<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt'><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Signal processing<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>PREP pipeline with line frequency removed = [50 100 150 200]; the other parameters are the default ones<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>b.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>high pass filtering @ 0.1 Hz<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>c.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>data segmentation in EX and IM conditions ([-1, 6] seconds), 40 trials per condition<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>d.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>PCA on the IM dataset (35 trials remained after trial rejection)<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>e.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Extended ICA with 27 PCs to retain (which explain the 99% of the variance)<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportLists]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><span style='mso-list:Ignore'>f.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>DIPFIT analysis using the MNI template and manual co-registration (the actual EGI channel positions are correctly loaded) returning an average residual variance of (0.5 +/- 0.2) which values seem too high to be taken into account for a following analysis of ICs.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>I have tried several modification to the above processing chain (e.g. low pass filtering @ 45 Hz; ICA on a larger number of PCs and on a larger number of trials (80); ICA performed with AMICA; ICA performed with Brain Vision Analyzer – Extended ICA) but with no improvement of the results. I have also tried on different datasets and tasks with the same results.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Do you all have any suggestion to achieve lower DIPFIT residual variance which are plausible from the neurophysiological point of view?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>I can also share a sample dataset if you consider it useful.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Thanks in advance,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Best,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>Giovanni <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p> </o:p></span></p></div></body></html>