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Hi all, <br>
<br>
Just adding this info for the sake of completeness. Thanks, Arjen,
for clarifying it!<br>
<br>
As I suspected, it's *really* not a good idea to use
ft_regressconfound before ICA. In fact, this function should be used
only at the very latest stages of your analysis, either just before
doing stats, or by incorporating the approach in the stats itself.<br>
<br>
Vitória<br>
<br>
<div class="moz-cite-prefix">On 10/29/2015 11:01 AM, Vitória Piai
wrote:<br>
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hi Steve, <br>
<br>
Thanks, sounds like a very reasonable explanation.<br>
I'm wondering whether I could use Arjen's correction for head
movement prior to ICA decomposition, but I can imagine there would
be problems with doing the regression first... I'll ask Arjen what
he thinks and post it here - if he doesn't see this before I see
him again - but I'd be curious to hear what you think as well.<br>
<br>
Thanks a lot!<br>
Vitoria<br>
<br>
<div class="moz-cite-prefix">On 10/28/2015 11:31 PM, Stephen
Politzer-Ahles wrote:<br>
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cite="mid:CAJT2k__N-Cmk7LpdGhVcj8UikUp9yUXwhGyrjktb_OjbhuRftA@mail.gmail.com"
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<div>Hello Vitoria,<br>
<br>
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I'm not sure, but one of my guesses would be head
movement. That is to say, if the participant moves her
head an inch (for example) then the same type of activity
is going to start appearing on different sensors, and if
that movement isn't corrected for then you can indeed
start seeing what looks like many copies of the same
component. (If you've done EEG, this is the same thing
that happens when, for example, you bring the same
participant back for multiple sessions on separate days
and concatenate the datasets together, but didn't put the
cap on on exactly the same place each time.) Do you have
marker measurements you can use to at least check how much
the head was moving, and perhaps to correct for movements
over the course of the session?<br>
<br>
</div>
Best,<br>
</div>
Steve<br>
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<br>
---<br>
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Stephen Politzer-Ahles<br>
University of Oxford<br>
Language and Brain Lab, Faculty of
Linguistics, Phonetics & Philology<br>
<a moz-do-not-send="true"
href="http://users.ox.ac.uk/%7Ecpgl0080/"
target="_blank">http://users.ox.ac.uk/~cpgl0080/</a></span></div>
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<blockquote class="gmail_quote" style="margin:0 0
0 .8ex;border-left:1px #ccc
solid;padding-left:1ex"> Message: 5<br>
Date: Wed, 28 Oct 2015 20:44:26 -0700<br>
From: Vit?ria Piai <<a moz-do-not-send="true"
href="mailto:v.piai.research@gmail.com">v.piai.research@gmail.com</a>><br>
To: FieldTrip discussion list <<a
moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:fieldtrip@science.ru.nl"><a class="moz-txt-link-abbreviated" href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a></a>><br>
Subject: [FieldTrip] many ICA components looking
the same<br>
Message-ID: <<a moz-do-not-send="true"
href="mailto:5631961A.1050507@gmail.com">5631961A.1050507@gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8";
Format="flowed"<br>
<br>
Hi everyone,<br>
<br>
I'm running ICA (cfg.method = 'runica') on CTF
data with 274 sensors. I<br>
was restricting my decomposition to 80
components at first, and it<br>
worked well for all previous patients.<br>
Somehow, for this particular patient, many of
the components have<br>
similar topography (I'm only showing till 42
below but the similarity<br>
continues for more components). Has anyone ever
seen this before?<br>
If I look at the time course of these
components, not all of them are<br>
clear eye-movements, but according to the
topography, you'd think they are.<br>
Any thoughts, like either changing the method or
rejecting only those<br>
components whose time courses clearly indicate
eye movements and keep<br>
other components despite their topographies?<br>
<br>
Thanks,<br>
Vitoria<br>
<br>
<br>
<br>
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