Well, I acknowledge that the labels are arbitrary at this point, but I propose to the eeglab community that we use the EOG labels as follows:<div><br></div><div>Horizontal:</div><div>H1: EOG on the Left Temple (H indicating horizontal)</div>
<div>H2: EOG on the Right Temple</div><div><br></div><div>Vertical:</div><div>VA1: EOG Above the Left Eye (V indicating Vertical)</div><div>VB1: EOG Below the Left Eye</div><div><br></div><div>VA2 and VB2 respectively on the right eye.</div>
<div><br></div><div>Mastoids (already agreed):</div><div>M1: Mastoid Left</div><div>M2: Mastoid Right</div><div><br></div><div><br></div><div>At least if I can have the coordinates of these positions (which some of you already agreed upon) it will be fabulous. And I think I would only include H1, H2, and VA1 and VA2 EOGs in my IC computations, because the VB1 and VB2 are generally prone to the local mouth, cheek and lip movements and may not be contaminating the EEGs that much. </div>
<div><br></div><div>Regarding to your findings, Ian, I think adding EOG channels will lead to the fallowing: Increase the number electrodes --> increase the number of of ICs --> which will naturally increase the number of artefact containing ICs --> this will bias some of the the artefactual ICs to shift towards the face or anterior regions. It looks like adding up EOGs in ICA based corrections/rejections is better to diagnose and differentiate very anterior components such as ELAN or LAN form the eye movement related artifects. For instance if you see an IC on F7 it is possible that it is a left anterior negativity but not an artefact. I recently used ADJUST, and I am wondering whether anyone using or developing ADJUST can help us to understand how ADJUST will behave in this case. I am very much interested in artefact correction. </div>
<div><br></div><div>Related to Scott's point: We use bipolar EOG electrodes in a BioSemi system and when we import the file into eeglab we use one of the mastoid electrodes as a reference. As far as I understand, bipolar electrodes referenced to the same electrode as the other EEG electrodes will not cause any problem for ICA based rejections in this case. Is this correct?</div>
<div><br></div><div>Thanks,</div><div><br></div><div>Baris </div><div><br></div><div> <br><br><div class="gmail_quote">On Sun, Sep 5, 2010 at 3:15 PM, Evans, Ian D. <span dir="ltr"><<a href="mailto:ievans@une.edu.au">ievans@une.edu.au</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="padding-left:10px;padding-right:10px;padding-top:15px" name="Compose message area">
<div><font size="2" face="Arial">Shall endeavor to find out this week, if there's
time amongst the residential schools. But from what I can discern the EOG
electrodes do seem to make a difference - when I ran an ICA on the eye
calibration task used to measure artifact without any EOG electrodes in the mix,
around 40 of the 68 components highlighted the F8 region as a strong source, and
this in a task purely involving eye movement, no other processing involved other
than possibly recognizing the shapes used to indicate where the subject should
look. Tried running it again but included </font><font size="2" face="Arial">some
estimated positions of EOG electrodes at the front, and there were still
40+ components all indicating activity at the frontal lobe, but now the activity
was around the face instead of F8. If nothing else, the EOG information should
assist ICA by isolating changes in multiple electrodes with correlate with the
EOG data and rendering it completely independent from the underlying actual
data.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">As for labels, well I couldn't find any consistent
EOG labeling systems for MATLAB, so why not start gathering labels? Let me
know what labels you use for the eye channels and I can build the .loc file -
David Groppe (many thanks again!) sent me a set of coordinates for the ocular
electrodes, but there is no problem with having multiple names for the same set
of coordinates - EEGLab detects what we're using anyway. Worth a
shot.</font></div>
<div> </div>
<div><font size="2" face="Arial"></font> </div>
<div><div class="im"><font size="2" face="Arial">Ian Evans<br>Cognitive and Affective
Neuroscience<br>University of New England.<br></font></div><a title="mailto:ievans@une.edu.au
CTRL + Click to follow link" href="mailto:ievans@une.edu.au" target="_blank"><font size="2" face="Arial">ievans@une.edu.au</font></a></div>
<div style="font:10pt Tahoma">
<div><font face="Arial"></font><font face="Arial"></font><br></div>
<div style="background:#f5f5f5">
<div><b>From:</b> <a title="mailto:demiral.007@googlemail.com
CTRL + Click to follow link" href="mailto:demiral.007@googlemail.com" target="_blank">Baris Demiral</a> </div>
<div><b>Sent:</b> Sunday, September 05, 2010 8:08 PM</div>
<div><b>To:</b> <a title="mailto:ievans@une.edu.au
CTRL + Click to follow link" href="mailto:ievans@une.edu.au" target="_blank">Evans, Ian D.</a> </div>
<div><b>Cc:</b> <a title="mailto:eeglablist@sccn.ucsd.edu
CTRL + Click to follow link" href="mailto:eeglablist@sccn.ucsd.edu" target="_blank">eeglablist@sccn.ucsd.edu</a> </div>
<div><b>Subject:</b> Re: [Eeglablist] Eye movement artifact in ICA - missing
coordinates for EOG electrodes</div></div></div><div><div></div><div class="h5">
<div><br></div>Hi Ian,
<div><br></div>
<div>I also made a similar query few months ago. I use 64 electrode 10-20 system
plus 4 EOGs. I asked whether there are specific labels for such EOG electrodes
in the standard-10-5-Cap385.sfp so that I can map these electrodes on the fly.
Are there labels for those, or can we decide and add those labels and
coordinates as a community together?</div>
<div><br></div>
<div>Actually, I find something more important: How much really does this
influence ICA related artifact detection and correction? Is there a huge change
when you include horizontal and vertical EOGs in the ICA based ERP calculations?
Are there others over there who compared ICA based
computations with and without including the EOG electrodes?</div>
<div><br></div>
<div>Baris</div>
<div><br>
<div class="gmail_quote">On Fri, Sep 3, 2010 at 7:42 AM, Evans, Ian D. <span dir="ltr"><<a href="mailto:ievans@une.edu.au" target="_blank">ievans@une.edu.au</a>></span>
wrote:<br>
<blockquote style="border-left:#ccc 1px solid;margin:0px 0px 0px 0.8ex;padding-left:1ex" class="gmail_quote">Greetings all! I'm trying to isolate eye movement artifact
with ICA in an<br>attempt to make EOG correction more accurate and hopefully
remove less of<br>the genuine underlying data that regression methods might
otherwise remove,<br>however I am having trouble tracking down a satisfactory
scalp map that<br>includes co-ordinates (Cartesian, 2D polar, 3D cylindrical)
for the EOG<br>electrodes on the face. Neither Neuroscan nor any setup or .loc
files in<br>EEGLab seem to provide these details, and all attempts to isolate
eye<br>movement in ICA without the location of the eye movement electrodes
have<br>been met with mocking laughter.<br><br>The recordings have already
been made on a 64-channel cap with six EOG<br>electrodes (one above and below
each eye, another beside each eye for<br>horizontal eye movement) using the
traditional 10-20 system. All<br>co-ordinates for the scalp are already at
hand, just the facial electrodes<br>are needed. If anyone can make such a
coordinate map available it would be<br>most helpful, thank you
kindly!<br><br>Ian Evans<br>Cognitive and Affective Neuroscience<br>University
of New
England.<br><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 title="mailto:eeglablist-request@sccn.ucsd.edu
CTRL + Click to follow link" href="mailto:eeglablist-request@sccn.ucsd.edu" target="_blank">eeglablist-request@sccn.ucsd.edu</a><br></blockquote></div><br><br clear="all"><br>-- <br>SB Demiral, PhD.<br>Department of Psychology <br>
7 George
Square<br>The University of Edinburgh<br>Edinburgh, EH8 9JZ<br>UK<br>Phone: +44
(0131) 6503063<br></div></div></div></div>
</blockquote></div><br><br clear="all"><br>-- <br>SB Demiral, PhD.<br>Department of Psychology <br>7 George Square<br>The University of Edinburgh<br>Edinburgh, EH8 9JZ<br>UK<br>Phone: +44 (0131) 6503063<br>
</div>