<div dir="ltr">Dear Makoto,<div><br></div><div><div>Thanks for your response!</div><div><br></div><div>I'll be analyzing my data in channel space, so I'll go with average referencing as you suggest. </div><div><br>
</div><div>Can you (or anyone else) please tell me whether to exclude bad channels (including both mastoids and any others) before or after applying a common average reference to the data?</div><div><br></div><div>Also, is it ok to re-reference to a common average after having completed the following processing steps: 1) remove DC offset, 2) 0.1 high-pass filter, 3) epoch the data? </div>
<div><br></div><div>Many thanks!</div><div>Becky</div><div><br></div></div></div><div class="gmail_extra"><br clear="all"><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">______________________________</span><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">______________</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">
<br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Becky Gilbert (nee Prince)</span><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">
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<br><br><div class="gmail_quote">On 25 September 2013 18:46, Makoto Miyakoshi <span dir="ltr"><<a href="mailto:mmiyakoshi@ucsd.edu" target="_blank">mmiyakoshi@ucsd.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Dear Becky,<div class="im"><div><br></div><div>> I believe the convention is to use the average of linked ears or mastoids as the reference for optimal measurement of these components,<br></div><div class="gmail_extra">
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</div></div><div class="gmail_extra">It depends on whether you want to use ICA to analyze your data in the source-resolved EEG or not. If you do, re-reference does not affect the ICA results. If you want to use channel EEG for the final analysis, I recommend average referencing. If you need to choose 1 electrode, choose Cz or FCz because that's another 'convention' I've seen so far (may not specific to your task though). Cz and FCz are easy to interpolate.</div>
<div class="gmail_extra"><br></div><div class="gmail_extra">Makoto</div><div class="gmail_extra"><br><div class="gmail_quote">2013/9/18 Becky Prince <span dir="ltr"><<a href="mailto:becky.prince@york.ac.uk" target="_blank">becky.prince@york.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 class="h5"><div dir="ltr">Dear EEGLAB list,<div>
<br></div><div>I've run an ERP study on auditory temporal expectations in which I'm interested in the auditory N2b and P3b components. I believe the convention is to use the average of linked ears or mastoids as the reference for optimal measurement of these components, but my mastoid channels are consistently noisy in all of my participants. The mastoid channels have higher impedances (~15 KOhms) than the other sites, probably due to the fact that the caps we use have built in mastoid sites that don't fit close enough to the skin. </div>
<div><br></div><div>I'm guessing it's a bad idea to re-reference to noisy channels, so I'm wondering what my options are. Can anyone explain what they would do in this situation? Are there any resources that explain the effects of re-referencing on specific components? I'm wondering if I'll be able to see changes in N2b/P3b if I use another reference, e.g. average of all electrodes, and how the appearance of the components (sites/polarities) will be different from those typically reported with a linked ear or mastoid reference.</div>
<div><br></div><div>Apologies for the fact that this isn't strictly an EEGLAB question - I'm hoping someone will still offer some advice!</div><div><br></div><div>Thanks,</div><div>Becky<br><div><div><span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">______________________________</span><span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">______________</span><br style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">
<br style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif"><span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">Becky Gilbert (nee Prince)</span><br style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">
<span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">PhD Researcher</span><div><br style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">
<span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">Room A109</span><div><span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">Department of Psychology</span><br style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">
<span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">University of York</span><div><span style="color:rgb(34,34,34);font-size:13px;font-family:arial,sans-serif">Heslington, York, YO10 5DD, UK</span><br>
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-- <br><div dir="ltr">Makoto Miyakoshi<br>Swartz Center for Computational Neuroscience<br>Institute for Neural Computation, University of California San Diego<br></div>
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