[Eeglablist] problem getting ICA to run properly on data files

[Emily Kappenman]

Hi Makoto,

Thanks for the response!  I think we have resolved this issue (or figured
out a work around, at least).  For some reason I was getting a 'boundary'
code at the beginning of my imported EEG files (using the File > Import
data > Using EEGLAB functions and plugins > From Brain Vis. rec .vhdr file
option), with a duration of 'NaN.'  This was causing errors in the filter I
was using in ERPLAB related to aligning the sampling points, and this was
causing ICA to not run properly.  If I remove this code from the beginning
of the data file, everything works normally again.  I'm not sure why this
code was appearing (there are no event codes at that time point in the EEG
data file, and we did not remove any segments in this time range offline
either).  I'm also exploring other import methods, using the suggestions
people have been providing in response to my other post.

Please let me know if you have any additional suggestions.

Thanks!
-Emily


On Wed, Apr 16, 2014 at 11:10 AM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu>wrote:

> Dear Emily,
>
> I can think of multiple reasons, such as severe rank reduction, huge
> artifacts, continuous zeros, etc etc... to diagnose it I need to ask you to
> send me a sample data to reproduce the problem. Are you willing to do it?
>
> Makoto
>
>
> 2014-04-09 16:17 GMT-07:00 Emily Kappenman <eskappenman at ucdavis.edu>:
>
>> Hi all,
>>
>> I have been using ICA for some time now to correct eye blink artifacts in
>> EEG data files with lots of success, but I just started using a new EEG
>> system and am running into problems getting ICA to run properly on the
>> files.  I am encountering the following error message: error: runica():
>> QUITTING - weight matrix may not be invertible!
>>
>> This occurs on data files from multiple subjects, of different lengths,
>> with different sampling rates, with different reference sites (both online
>> and offline), etc..  Sometimes ICA will run but will require multiple
>> separate components for eye blinks (5 or 6 out of 31 components).  The
>> number of the components in the list that relate to the eye blinks also
>> seems to correspond to channel numbers in a systematic way (e.g., if FP2
>> was channel 30 in the data set, component 30 is one of the components,
>> etc.).
>>
>> Has anyone encountered anything like this before or have any ideas what
>> might be causing this?  Any suggestions are much appreciated!
>>
>> Thanks so much!
>> -Emily Kappenman
>>
>> --
>> --------------------------------------------------------------------
>> Emily S. Kappenman, Ph.D.
>> UC Davis Center for Mind and Brain
>> 267 Cousteau Place
>> Davis, CA 95618
>> eskappenman at ucdavis.edu
>> --------------------------------------------------------------------
>>
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>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>



-- 
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Emily S. Kappenman, Ph.D.
UC Davis Center for Mind and Brain
267 Cousteau Place
Davis, CA 95618
eskappenman at ucdavis.edu
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