<html dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-2">
<style id="owaParaStyle" type="text/css">P {margin-top:0;margin-bottom:0;}</style>
</head>
<body ocsi="0" fpstyle="1">
<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Just wanted to add small side note to the question/answer quoted below:<br>
<br>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px">> The previous messages largely answer my query, but I'd like just to make sure I understand correctly. The results of ICA decomposition should be similar whether the data is epoched or not-
is that correct? </span></div>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px"><br>
</span></div>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px">> Correct. If you have the same number of datapoint before and after epoching, ICA results should be as identical as the two results from running ICA twice on the same data.<br>
<br>
<br>
I think generally ICA won't give identical results when run several times even on the same data as it is a stochastic process. Otherwise there would not exist software packages that assess ICA decomposition stability (e.g. ICASSO).</span>
<br>
<br>
<br>
<br>
</div>
<div style="font-family: Times New Roman; color: #000000; font-size: 16px">
<hr tabindex="-1">
<div style="direction: ltr;" id="divRpF267158"><font color="#000000" face="Tahoma" size="2"><b>From:</b> eeglablist-bounces@sccn.ucsd.edu [eeglablist-bounces@sccn.ucsd.edu] on behalf of Makoto Miyakoshi [mmiyakoshi@ucsd.edu]<br>
<b>Sent:</b> Wednesday, September 11, 2013 4:06 AM<br>
<b>To:</b> Katherine Naish<br>
<b>Cc:</b> eeglablist@sccn.ucsd.edu<br>
<b>Subject:</b> Re: [Eeglablist] Epoching eeg data<br>
</font><br>
</div>
<div></div>
<div>
<div dir="ltr">Dear Katherine,
<div><br>
</div>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px">> The previous messages largely answer my query, but I'd like just to make sure I understand correctly. The results of ICA decomposition should be similar whether the data is epoched or not-
is that correct? </span></div>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px"><br>
</span></div>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px">Correct. If you have the same number of datapoint before and after epoching, ICA results should be as identical as the two results from running ICA twice on the same data.</span></div>
<div><br>
</div>
<div><span style="font-family:Tahoma; font-size:13.333333015441895px">> Obviously the results will be different if the data itself is different, but does ICA essentially treat epoched data as a continuous section?</span></div>
<div><font face="Tahoma"><br>
</font></div>
<div>
<div class="gmail_extra">ICA shuffles all datapoints as a preprocess; thus the concept of time disappears.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra"><span style="font-family:Tahoma; font-size:13.333333015441895px">> My pre-processing order is the following: resample, filter, epoch, remove baseline, interpolate bad channels and remove bad epochs (based on visual inspection), re-reference
to average, and (finally) run ICA to detect artefacts.</span></div>
<div class="gmail_extra"><span style="font-family:Tahoma; font-size:13.333333015441895px"><br>
</span></div>
<div class="gmail_extra"><span style="font-family:Tahoma">It looks ok.</span></div>
<div class="gmail_extra"><span style="font-family:Tahoma; font-size:13.333333015441895px"><br>
</span></div>
<div class="gmail_extra"><span style="font-family:Tahoma; font-size:13.333333015441895px">> One thing I wasn't sure about was re-referencing- am i doing that at the right point?</span><br>
</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">Yes.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">Makoto</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2013/9/10 Katherine Naish <span dir="ltr"><<a href="mailto:K.R.Naish@pgr.reading.ac.uk" target="_blank">K.R.Naish@pgr.reading.ac.uk</a>></span><br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex; border-left-width:1px; border-left-color:rgb(204,204,204); border-left-style:solid; padding-left:1ex">
<div>
<div style="direction:ltr; font-size:10pt; font-family:Tahoma">
<p>Dear all,</p>
<p> </p>
<p></p>
<p>The previous messages largely answer my query, but I'd like just to make sure I understand correctly. The results of ICA decomposition should be similar whether the data is epoched or not- is that correct? Obviously the results will be different if the data
itself is different, but does ICA essentially treat epoched data as a continuous section?</p>
<p> </p>
<p>I would also really appreciate it if someone could approve, or otherwise, my pre-processing order. My pre-processing order is the following: resample, filter, epoch, remove baseline, interpolate bad channels and remove bad epochs (based on visual inspection),
re-reference to average, and (finally) run ICA to detect artefacts. One thing I wasn't sure about was re-referencing- am i doing that at the right point?</p>
<p> </p>
<p>Many thanks in advance,</p>
<p>katherine</p>
<div>
<p> </p>
<div style="font-family:Tahoma; font-size:13px">
<div style="font-family:Tahoma; font-size:13px">
<div style="font-family:Tahoma; font-size:13px">
<div style="font-family:Tahoma; font-size:13px">
<div style="font-size:13px"> </div>
<div style="font-size:13px">
<div style="font-size:13px">
<div style="font-size:13px"></div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div style="font-size:16px; font-family:'Times New Roman'">
<hr>
<div style="direction:ltr"><font color="#000000" face="Tahoma"><b>From:</b> <a href="mailto:eeglablist-bounces@sccn.ucsd.edu" target="_blank">
eeglablist-bounces@sccn.ucsd.edu</a> [<a href="mailto:eeglablist-bounces@sccn.ucsd.edu" target="_blank">eeglablist-bounces@sccn.ucsd.edu</a>] on behalf of Mikołaj Magnuski [<a href="mailto:imponderabilion@gmail.com" target="_blank">imponderabilion@gmail.com</a>]<br>
<b>Sent:</b> 06 June 2013 19:13<br>
<b>Cc:</b> <a href="mailto:eeglablist@sccn.ucsd.edu" target="_blank">eeglablist@sccn.ucsd.edu</a><br>
<b>Subject:</b> Re: [Eeglablist] Epoching eeg data<br>
</font><br>
</div>
<div>
<div class="h5">
<div></div>
<div>Dear Karlo,
<div><br>
</div>
<div>there is a case when dividing your whole 15 min. into smaller epochs (say 1 or 2 seconds long)</div>
<div>is quite convenient with respect to ICA:</div>
<div>--> cleaning data before ICA is easy if you just have to click bad epochs instead of marking</div>
<div>bad periods in continuous data - although this is just my personal feeling. </div>
<div>Nevertheless, you can also use automatic artifact rejection methods</div>
<div>available in EEGlab this way. These methods require epoched data. </div>
<div>(it is also easy to reconstruct your rejections later if you do them</div>
<div>on epochs - you can just <span>save the indices of windows that you removed [by </span></div>
<div>coping relevant field in EEG <span>structure after marking bad epochs</span><span>,</span></div>
<div><span>but before rejecting them]).</span></div>
<div><span>--> Then, after your first IC decomposition, if you are not satisfied with its results and observe that</span></div>
<div><span>some parts of your data may be responsible for poor results - you can remove</span></div>
<div><span>epochs containing these data easily and perform ICA again.</span></div>
<div><span><br>
</span></div>
<div><span>So, just as Makoto wrote, ICA does not care whether data are epoched<span></span> but you may -</span></div>
<div><span>because in some cases it is conven</span><span>ient in preprocessing or 'postprocessing' (correcting</span></div>
<div></div>
<div><span>ICA decomposition).</span></div>
<div><span>If you need any extra help with this - let me know (I have some scripts and functions to do this).</span></div>
<div><span><br>
</span></div>
<div><span>Mikolaj</span></div>
<div><span><br>
</span></div>
<div></div>
<div></div>
<div><br>
W dniu środa, 5 czerwca 2013 użytkownik Makoto Miyakoshi napisał:<br>
<blockquote class="gmail_quote" style="border-left-color:rgb(204,204,204); border-left-width:1px; border-left-style:solid; margin:0px 0px 0px 0.8ex; padding-left:1ex">
<div dir="ltr">Dear Karlo,
<div><br>
</div>
<div>If you want to epoch your data into 3-min blocks, for example, put event markers every 3 minutes then epoch the data.</div>
<div><br>
</div>
<div>ICA does not care temporal continuity of the data since it shuffles them up differently for every iteration as a preprocess. That means, if the total number of datapoints are the same before and after the epoching, the ICA results should be the same.</div>
<div><br>
</div>
<div>Makoto</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">2013/6/3 karlo gonzales <span dir="ltr"><<a href="https://dbxprd0111.outlook.com/owa/UrlBlockedError.aspx" target="_blank">thats_karlo@yahoo.com</a>></span><br>
<blockquote class="gmail_quote" style="border-left-color:rgb(204,204,204); border-left-width:1px; border-left-style:solid; margin:0px 0px 0px 0.8ex; padding-left:1ex">
<div>
<div style="font-family:arial,helvetica,sans-serif; font-size:10pt">
<div><font face="arial, helvetica, sans-serif">Dear EEGlab experts,</font></div>
<div style="font-family:arial,helvetica,sans-serif; font-size:10pt"><br>
</div>
<div style="background-color:transparent"><font face="arial, helvetica, sans-serif">I need you help regarding an</font><span style="background-color:transparent"><font face="arial, helvetica, sans-serif"> eeg data files which was recorded during eye closed
state (15 min long). Thus, there is no event to epoch the data. 1) How do you epoch such data</font></span><span style="background-color:transparent; font-style:normal; font-family:arial,helvetica,sans-serif; font-size:small">? 2) should we epoch data before
running ica (dose more epoch means better results?)</span></div>
<div style="background-color:transparent; font-style:normal; font-family:arial,helvetica,sans-serif; font-size:13px">
<font face="arial, helvetica, sans-serif">Thanks in advance</font></div>
</div>
</div>
<br>
_______________________________________________<br>
Eeglablist page: <a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" target="_blank">
http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br>
To unsubscribe, send an empty email to <a href="https://dbxprd0111.outlook.com/owa/UrlBlockedError.aspx" target="_blank">
eeglablist-unsubscribe@sccn.ucsd.edu</a><br>
For digest mode, send an email with the subject "set digest mime" to <a href="https://dbxprd0111.outlook.com/owa/UrlBlockedError.aspx" target="_blank">
eeglablist-request@sccn.ucsd.edu</a><br>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
<div dir="ltr">Makoto Miyakoshi<br>
Swartz Center for Computational Neuroscience<br>
Institute for Neural Computation, University of California San Diego<br>
</div>
</div>
</blockquote>
</div>
<br>
<br>
-- <br>
Pozdrawiam,<br>
Mikołaj Magnuski<br>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
_______________________________________________<br>
Eeglablist page: <a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" target="_blank">
http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br>
To unsubscribe, send an empty email to <a href="mailto:eeglablist-unsubscribe@sccn.ucsd.edu" target="_blank">
eeglablist-unsubscribe@sccn.ucsd.edu</a><br>
For digest mode, send an email with the subject "set digest mime" to <a href="mailto:eeglablist-request@sccn.ucsd.edu" target="_blank">
eeglablist-request@sccn.ucsd.edu</a><br>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
<div dir="ltr">Makoto Miyakoshi<br>
Swartz Center for Computational Neuroscience<br>
Institute for Neural Computation, University of California San Diego<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>