And for a related perspective, see <br><br><span class="SpellE"><span style="font-size:11.0pt;font-family:
"Arial","sans-serif";color:black">McMenamin</span></span><span style="font-size:11.0pt;font-family:"Arial","sans-serif";color:black">,
B. W., <b style="mso-bidi-font-weight:normal">Shackman, A. J.</b>, <span class="SpellE">Greischar</span>, L. L. & Davidson, R. J. (2011). <span class="SpellE">Electromyogenic</span> artifacts and
electroencephalographic inferences revisited, <span class="SpellE"><b style="mso-bidi-font-weight:normal"><i style="mso-bidi-font-style:normal">Neuroimage</i></b></span><i style="mso-bidi-font-style:normal">, 54</i>, 4-9. <br>
<br><a href="http://psyphz.psych.wisc.edu/~shackman/mcmenamin_shackman_ni2011.pdf">http://psyphz.psych.wisc.edu/~shackman/mcmenamin_shackman_ni2011.pdf</a><br><br></span><br><div class="gmail_quote">On Mon, May 23, 2011 at 8:07 PM, Joseph Dien <span dir="ltr"><<a href="mailto:jdien07@mac.com">jdien07@mac.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div style="word-wrap:break-word"><div>I agree with David's reasoning. You may find the following article to be of help as well in understanding the issues involved:</div>
<div><br></div><div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">Dien, J., Khoe, W., & Mangun, G. R. (2007). Evaluation of PCA and ICA of simulated ERPs: Promax versus Infomax rotations. <i>Human Brain Mapping</i>, <span style="font:13.0px 'Lucida Grande'">28</span><span style="font:12.0px 'Lucida Grande'">(</span><span style="font:13.0px 'Lucida Grande'">8</span>), <span style="font:13.0px 'Lucida Grande'">742-763</span>.</div>
</div><div><br></div><div>Cheers!</div><div><br></div><div>Joe</div><br><div><div>On May 23, 2011, at 11:57 AM, David Groppe wrote:</div><br><blockquote type="cite"><div>Hi Odelia,<br> When you use ICA (or any other spatial filter) to correct for EEG<br>
artifacts, you're going to distort your data some by removing true EEG<br>activity in addition to the artifact (for an explanation, see:<br><a href="http://www.cogsci.ucsd.edu/%7Edgroppe/PUBLICATIONS/GroppeCSO2008.pdf" target="_blank">http://www.cogsci.ucsd.edu/%7Edgroppe/PUBLICATIONS/GroppeCSO2008.pdf</a>).<br>
So to minimize distortion, it would be better not to apply ICA<br>artifact correction to artifact-free data. However, if the frequency<br>of the artifact differs across experimental conditions, it could<br>confound your analysis. For example, I suspect people blink more<br>
often to targets in an oddball experiment than standards. Thus if you<br>apply ICA only to blinky trials, you could find a difference between<br>the EEG response to standards and targets that simply reflects the<br>fact ICA removed more EEG activity in the target trials (i.e., it<br>
wouldn't reflect a true difference in neural processing).<br> hope this helps,<br> -David<br><br>On Mon, May 23, 2011 at 1:44 AM, odelia nakar <<a href="mailto:odidodi@hotmail.com" target="_blank">odidodi@hotmail.com</a>> wrote:<br>
<blockquote type="cite">Hi all,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I'm troubled by the fact that when I use ICA for blinks\eyes movements<br></blockquote><blockquote type="cite">
removal, I remove the relevant components also from trials that do not<br></blockquote><blockquote type="cite">contain blinks\eyes movements. In order to avoid this bias we thought to<br></blockquote><blockquote type="cite">
combine the data before ICA ("data" structure) with the data after ICA<br></blockquote><blockquote type="cite">("dataica" structure), only in specific trials, as follows:<br></blockquote><blockquote type="cite">
<br></blockquote><blockquote type="cite">datall=dataica;<br></blockquote><blockquote type="cite">datall.trial=data.trial;<br></blockquote><blockquote type="cite">datall.time=data.time;<br></blockquote><blockquote type="cite">
blinks=[2 4 5 8 bla bla 156];<br></blockquote><blockquote type="cite">for ind=1:length(blinks)<br></blockquote><blockquote type="cite"> datall.trial{1,blinks(ind)}=dataica.trial{1,blinks(ind)};<br></blockquote><blockquote type="cite">
end<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">To my first question: I just wanted to check that there is no problem with<br></blockquote><blockquote type="cite">that, or any reason not to use it.<br>
</blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Another issue- I use motor learning task, and I'm trying to understand what<br></blockquote><blockquote type="cite">happens through the process, in terms of power-frequency changes through the<br>
</blockquote><blockquote type="cite">process. How would you recommend that I'd use the ft_freqanalysis function?<br></blockquote><blockquote type="cite">What method to use (or what do I need to consider when choosing the method<br>
</blockquote><blockquote type="cite">field)?<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Thanks a lot,<br></blockquote><blockquote type="cite">
Odelia.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">_______________________________________________<br></blockquote><blockquote type="cite">fieldtrip mailing list<br></blockquote><blockquote type="cite">
<a href="mailto:fieldtrip@donders.ru.nl" target="_blank">fieldtrip@donders.ru.nl</a><br></blockquote><blockquote type="cite"><a href="http://mailman.science.ru.nl/mailman/listinfo/fieldtrip" target="_blank">http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a><br>
</blockquote><blockquote type="cite"><br></blockquote><br><br><br>-- <br>David Groppe, Ph.D.<br>Postdoctoral Researcher<br>Kutaslab<br>Dept. of Cognitive Science<br>University of California, San Diego<br><a href="http://www.cogsci.ucsd.edu/%7Edgroppe/" target="_blank">http://www.cogsci.ucsd.edu/~dgroppe/</a><br>
<br>_______________________________________________<br>fieldtrip mailing list<br><a href="mailto:fieldtrip@donders.ru.nl" target="_blank">fieldtrip@donders.ru.nl</a><br><a href="http://mailman.science.ru.nl/mailman/listinfo/fieldtrip" target="_blank">http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a><br>
</div></blockquote></div><br><div>
<div style="word-wrap:break-word"><span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:medium;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:medium;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:medium;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Courier;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<div><div><div><div><div><br>--------------------------------------------------------------------------------</div><div><br></div><div>Joseph Dien</div><div>E-mail: <a href="mailto:jdien07@mac.com" target="_blank">jdien07@mac.com</a></div>
<div>Phone: <a href="tel:301-226-8848" value="+13012268848" target="_blank">301-226-8848</a></div><div>Fax: <a href="tel:301-226-8811" value="+13012268811" target="_blank">301-226-8811</a></div><div><a href="http://homepage.mac.com/jdien07/" target="_blank">http://homepage.mac.com/jdien07/</a></div>
</div></div><br></div><div><br></div><div><br></div><br></div></div></span></div></span></div></span></div></span></div></span></div></span></div></span><br></div><br><br>
</div>
<br></div><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" target="_blank">http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a><br>
<br></blockquote></div><br><br clear="all"><br>-- <br>Alexander J. Shackman, Ph.D.<br>Wisconsin Psychiatric Institute & Clinics and<br>Department of Psychology<br>University of Wisconsin-Madison<br>1202 West Johnson Street<br>
Madison, Wisconsin 53706<br><br>Telephone: +1 (608) 358-5025<br>Fax: +1 (608) 265-2875<br>Email: <a href="mailto:shackman@wisc.edu">shackman@wisc.edu</a><br><a href="http://psyphz.psych.wisc.edu/~shackman">http://psyphz.psych.wisc.edu/~shackman</a><br>