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<div class="moz-cite-prefix">Actually the question can be asked in
another way:<br>
<br>
What happens to phase information when the ICA based artifact
rejection is used, such that artifactual ICs are taken out, and
the data is reconstructed back again with the rest of the ICs? Why
would I prefer ICA correction rather than regression based
correction?<br>
<br>
Best,<br>
Baris<br>
<br>
On 04/04/2013 11:08 AM, Makoto Miyakoshi wrote:<br>
</div>
<blockquote
cite="mid:CAEqC+SUPHWfdK8ac2V-E_sKeFXqmb6od4OwcUebGkWTZRBjgFg@mail.gmail.com"
type="cite">
<div dir="ltr">Dear Karlo,
<div><br>
</div>
<div style="">ICA is to generate spatial filter
(EEG.icaweight*EEG.icasphere) and IC activities. Scalp channel
EEG remains unaffected.<br>
</div>
<div style=""><br>
</div>
<div style=""><span
style="font-size:12.666666984558105px;background-color:transparent;font-family:'times
new roman','new york',times,serif">>Indeed, i like to
know: how ICA may affect the coherency</span><span
style="font-size:12.666666984558105px;background-color:transparent;font-family:'times
new roman','new york',times,serif"> between channel_1
(alpha-band) and channel_2</span><span
style="font-size:12.666666984558105px;background-color:transparent;font-family:'times
new roman','new york',times,serif"> (beta-band)? </span><br>
</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">ICA does not change anything, it just
generates parallel data.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">Makoto<br>
<br>
<div class="gmail_quote">
2013/4/3 karlo gonzales <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:thats_karlo@yahoo.com" target="_blank">thats_karlo@yahoo.com</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="font-size:10pt;font-family:arial,helvetica,sans-serif">
<div
style="font-family:arial,helvetica,sans-serif;font-size:10pt"><span>Thanks
for your prompt reply. and </span><font
style="background-color:transparent">my apology,
if my question was not clear enough.</font></div>
<div
style="font-style:normal;font-size:12.800000190734863px;background-color:transparent;font-family:arial,helvetica,sans-serif"><font
style="background-color:transparent"> My concern
is not about </font><span
style="background-color:transparent"><font
face="times new roman, new york, times, serif">phases
between channels and ICs. </font></span><span
style="font-family:'times new roman','new
york',times,serif;background-color:transparent">Indeed,
i like to know: how ICA may affect the coherency</span><span
style="font-family:'times new roman','new
york',times,serif;background-color:transparent"> between
channel_1 (alpha-band) and channel_2</span><span
style="font-family:'times new roman','new
york',times,serif;background-color:transparent"> (beta-band)?
does ICa will shift phase of alpha or beta?</span></div>
<div
style="font-style:normal;font-size:12.800000190734863px;background-color:transparent;font-family:'times
new roman','new york',times,serif"><span
style="font-family:'times new roman','new
york',times,serif;background-color:transparent"><br>
</span></div>
<div
style="font-style:normal;font-size:12.800000190734863px;background-color:transparent;font-family:'times
new roman','new york',times,serif"><span
style="font-family:'times new roman','new
york',times,serif;background-color:transparent">Thanks
again,</span></div>
<div><span style="font-family:'times new roman','new
york',times,serif;background-color:transparent">Karlo</span></div>
<div
style="font-style:normal;font-size:12.800000190734863px;background-color:transparent;font-family:'times
new roman','new york',times,serif">
<span style="font-family:'times new roman','new
york',times,serif;background-color:transparent"><br>
</span></div>
<div class="">
<div
style="font-style:normal;font-size:13.600000381469727px;background-color:transparent;font-family:arial,helvetica,sans-serif"><br>
</div>
<div
style="font-family:arial,helvetica,sans-serif;font-size:10pt"><br>
</div>
</div>
<div
style="font-family:arial,helvetica,sans-serif;font-size:10pt">
<div class=""> </div>
<div style="font-family:'times new roman','new
york',times,serif;font-size:12pt">
<div class="">
<div dir="ltr"> <font face="Arial">
<hr size="1"> <b><span
style="font-weight:bold">From:</span></b>
Makoto Miyakoshi <<a
moz-do-not-send="true"
href="mailto:mmiyakoshi@ucsd.edu"
target="_blank">mmiyakoshi@ucsd.edu</a>><br>
<b><span style="font-weight:bold">To:</span></b>
karlo gonzales <<a moz-do-not-send="true"
href="mailto:thats_karlo@yahoo.com"
target="_blank">thats_karlo@yahoo.com</a>>
<br>
<b><span style="font-weight:bold">Cc:</span></b>
EEGLAB List <<a moz-do-not-send="true"
href="mailto:eeglablist@sccn.ucsd.edu"
target="_blank">eeglablist@sccn.ucsd.edu</a>>
<br>
<b><span style="font-weight:bold">Sent:</span></b>
Wednesday, April 3, 2013 9:36:51 PM<br>
<b><span style="font-weight:bold">Subject:</span></b>
Re: phase shift and ICA<br>
</font> </div>
</div>
<div>
<div class="h5"> <br>
<div>
<div dir="ltr">Dear Dr. Gonzales,
<div><br>
</div>
<div>I suppose you mean you compare phases
between channels and ICs. It's not shift
that makes difference between scalp
channel ICs and EEGs. Let me explain
what it is. Let's say we have only 2
channels and 2 ICs. The relation of
scalp channel EEG and ICs are like this:</div>
<div><br>
</div>
<div>Channel 1 = 0.3 X IC1 + 0.7 X IC2</div>
<div>Channel 2 = 0.7 x IC1 + 0.3 x IC2</div>
<div><br>
</div>
<div>Here I determined 0.3 and 0.7
arbitrarily but actually these are
determined by ICA. Anyway, when you
compare Channel 1 with IC1 in the above
example, they are dissimilar to each
other NOT because of phase shift (unless
IC1 and IC2 are similar, which is hard
to imagine since they are supposed to be
temporally independent).</div>
<div><br>
</div>
<div>If the decomposition is like</div>
<div><br>
</div>
<div>
<div>Channel 1 = 0.99999 X IC1 + 0.00001
X IC2</div>
<div>Channel 2 = 0.00001 x IC1 +
0.99999 x IC2</div>
</div>
<div>
<br>
</div>
<div>Then your Channel 1 and IC1 should be
very similar.</div>
<div><br>
</div>
<div>Makoto</div>
<div><br>
</div>
</div>
<div><br>
<br>
<div>2013/4/3 karlo gonzales <span
dir="ltr"><<a
moz-do-not-send="true"
rel="nofollow"
href="mailto:thats_karlo@yahoo.com"
target="_blank">thats_karlo@yahoo.com</a>></span><br>
<blockquote 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="font-size:10pt;font-family:arial,helvetica,sans-serif">
<div>
<div>
<div
style="font-family:arial,helvetica,sans-serif">
<div
style="font-size:10pt;font-family:arial,helvetica,sans-serif">Dear
Dr.<span
style="font-size:small;color:rgb(34,34,34);font-family:arial,sans-serif;line-height:16px"> </span><i>Miyakoshi,</i></div>
<div
style="font-style:normal;font-size:13px;background-color:transparent;font-family:arial,sans-serif"><i><br>
</i></div>
<div
style="background-color:transparent"><span><span><font><i><span><span
style="line-height:16px">I am using EEGLAB and ICA tools to clean EEG
data. i
am recording
EEG from a 64
channel cap
(NEUROSCAN),
with a fixed
reference electrode,
which
is located
between CZ and
CPZ. </span></span></i></font></span></span></div>
<div
style="background-color:transparent"><font
face="arial, sans-serif"><i><span
style="line-height:16px">i do not re-reference my data for further
analysis.</span></i></font><i
style="line-height:16px;font-size:13px;font-family:arial,sans-serif;background-color:transparent"> So,
i just wonder, if
applying ICA, would
shift the phase of
signals (specially low
frequency)? is there
anyway to check it? </i></div>
<div
style="background-color:transparent"><i
style="line-height:16px;font-size:13px;font-family:arial,sans-serif;background-color:transparent"><br>
</i></div>
<div
style="background-color:transparent"><i
style="line-height:16px;font-size:13px;font-family:arial,sans-serif;background-color:transparent">many
many thanks for all your
help and support,</i></div>
<div
style="background-color:transparent"><i
style="line-height:16px;font-size:13px;font-family:arial,sans-serif;background-color:transparent">Karlo</i></div>
<div
style="background-color:transparent"><span><span><font><span
style="line-height:16px"><i><br>
</i></span></font></span></span></div>
<div
style="font-size:10pt;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><span
style="line-height:16px;font-style:italic;font-size:13px;font-family:arial,sans-serif"><br>
</span></span></div>
<div
style="font-size:10pt;background-color:transparent;font-family:arial,helvetica,sans-serif"><br>
</div>
<div
style="font-style:italic;font-size:13px;background-color:transparent;font-family:arial,sans-serif"><span
style="font-family:arial,sans-serif;font-size:13px;font-style:italic;line-height:16px;background-color:transparent"><br>
</span></div>
<div
style="font-style:normal;font-size:13px;background-color:transparent;font-family:arial,sans-serif"><span><span
style="line-height:16px;font-style:italic;font-size:13px;font-family:arial,sans-serif"><br>
</span></span></div>
<div
style="font-style:italic;font-size:13px;background-color:transparent;font-family:arial,sans-serif"><span><span
style="line-height:16px;font-style:italic;font-size:13px;font-family:arial,sans-serif"><br>
</span></span></div>
</div>
</div>
</div>
</div>
</div>
</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>
<br>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</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>
<br>
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