<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)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
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.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.EmailStyle17
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
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-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Using a steeply notched filter will distort your waveforms this looks like you might have had a significant impedance mismatch on several of your electrodes.<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">Herbert jay Gould, Ph.D.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">School of Communication Sciences and Disorders<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The University of Memphis<br>
<br>
<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>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> fieldtrip-bounces@science.ru.nl [mailto:fieldtrip-bounces@science.ru.nl]
<b>On Behalf Of </b>Pelt, S. van (Stan)<br>
<b>Sent:</b> Tuesday, March 17, 2015 11:03 AM<br>
<b>To:</b> FieldTrip discussion list<br>
<b>Subject:</b> Re: [FieldTrip] Decreased coherence at 60Hz?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Daria,<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">As far as I know, signal power influences coherence measures. So, in your case, it might be that you have relatively large power and/or SNR differences between
your electrodes, that might underlie your results. You might consider using a notch filter to filter the 60 Hz signal out, or stratifying your trials to compensate for SNR differences.<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 lang="NL" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NL" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Stan<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NL" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NL" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Stan van Pelt, PhD<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Donders Institute for Brain, Cognition and Behaviour<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Radboud University<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Montessorilaan 3, B.01.34<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">6525 HR Nijmegen, the Netherlands<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NL" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">tel: +31 24 3616288
<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"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:fieldtrip-bounces@science.ru.nl">fieldtrip-bounces@science.ru.nl</a>
<a href="mailto:[mailto:fieldtrip-bounces@science.ru.nl]">[mailto:fieldtrip-bounces@science.ru.nl]</a>
<b>On Behalf Of </b>Daria Boratyn<br>
<b>Sent:</b> dinsdag 17 maart 2015 16:42<br>
<b>To:</b> <a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a><br>
<b>Subject:</b> [FieldTrip] Decreased coherence at 60Hz?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><span lang="NL"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span lang="NL">Hi all,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="NL"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="NL">Using FieldTrip, I created bipolar montages on each hemisphere and then calculated the coherence between those. I am getting an odd result and seeing a decrease in coherence at 60Hz for some of my runs. My understanding
is that 60 cycle noise should be picked up by every electrode and would therefore have high coherence values across the board. Would anyone have a suggestions as to what could be causing this? I’ve attached a screenshot of what I’m seeing. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="NL">Thank you,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="NL">Daria<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="NL"><img border="0" width="512" height="416" id="_x0000_i1025" src="cid:image001.png@01D060A8.18FB77D0"><o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span lang="NL"><o:p> </o:p></span></p>
</div>
</body>
</html>