[Eeglablist] Problem with channel detection in Run ICA

[Makoto Miyakoshi]

Dear Jan,

Sorry. GUI stands for graphical user interface. It seems you have used
some function to select channels before running ICA... Is it a part of
ICA function? I want to know in which process and how you used it.
Thank you for your patience.

Yokohama is a beautiful place. There is a huge Ferris wheel, and you
can enjoy a night scene from it. I hope you enjoy Yokohama.

Makoto

2012/6/28 Remi, Jan Dr. <Jan.Remi at med.uni-muenchen.de>:
> Dear Makoto,
> I am currently not at the office but at a conference in Yokohama, Japan, so I can't answer your question right away. could you specifiy your question regarding GUI? What is GUI? ( I am just not aware of that abbreviation.
> Thank you!
> Jan
> ________________________________________
> Von: Makoto Miyakoshi [mmiyakoshi at ucsd.edu]
> Gesendet: Mittwoch, 27. Juni 2012 20:09
> An: Remi, Jan Dr.
> Cc: eeglablist at sccn.ucsd.edu; catarinaduarte86 at gmail.com
> Betreff: Re: [Eeglablist] Problem with channel detection in Run ICA
>
> Dear Jan,
>
>> More over, the channels that are not displayed in the channel selection
>> dialog before running the ICA is not systematic, once it was for example the
>> EEG channel F5, once the EEG channel P7.
>
> Now I don't understand this part. Could you please tell me which
> function you selected from GUI?
>
> Makoto
>
> 2012/6/21 Remi, Jan Dr. <Jan.Remi at med.uni-muenchen.de>:
>> Dear EEGLAB users,
>>
>> I am using EEGLAB to run an ICA on my EEG data that I acquire in an EEG-fMRI
>> environment to ultimately get rid of the cardioballistogram artifact that is
>> typical for recording EEG inside the strong magnet of an MRI machine.
>>
>> Recently I get a message that reads as follows:
>> "EEGLAB has detected that the rank of your data matrix is lower [than] the
>> number of input data channels. This might be because you are including a
>> reference channel or because you are running a second ICA decomposition. The
>> proposed dimension for ICA is 57 (out of 62 channels). Rank computation may
>> be inaccurate so you may edit this number below. If you do not understand,
>> simply press OK below."
>>
>> Besides being very thankful for the last sentence, I really do not
>> understand the problem. Actually the number of channels that EEGLAB proposes
>> varies between 57 and 60 (out of the actual 62 channels) for the 6 files I
>> want to run the ICA on. These files differ only in the stimulus condition,
>> the EEG properties are not changed at all, they are recorded on the same EEG
>> machine (Neuroscan Maglink), with the exact same setup for approximately the
>> same time (about 9:45 minutes each). So while I of course do expect the EEG
>> to differ in some properties of the EEG signal, i.e. changes in gamma band
>> etc., the recording setup conditions are the same. So I do not see where
>> there would be a systematic mistake in the recording, especially since I
>> have had the same failure notice on a data set, where I had used the ICA
>> before without any problem and then 2 weeks later, when I wanted to redo the
>> ICA on the same EEG data, where I had only applied a different filter in the
>> Neuroscan software before running the ICA analysis (a different low
>> frequency filter), I get the same failure notice.
>> More over, the channels that are not displayed in the channel selection
>> dialog before running the ICA is not systematic, once it was for example the
>> EEG channel F5, once the EEG channel P7.
>>
>> The ICA itself gets me great decomposition, I can get rid of the artifact
>> very nicely, I am happy with the resulting data, but I don't like the idea,
>> that I am possibly systematically missing data. I do read the EEG in a
>> clinical way, I am a medical researcher.
>>
>> Any ideas where my mistake could be?
>> A similar question had been asked in 2011 and 2009, mainly pertaining to a
>> problem of displaying all channels in a 32 bit dataset.
>>
>> In case you need screenshots of my problem I will be happy to answer emails
>> to my email-adress directly.
>>
>> Thank you all, I enjoy EEGLAB and its community a lot,
>>
>> Jan Rémi
>> Epilepsy and Sleep Center, Department of Neurology, University of Munich
>> currently: Department of Neurology, University of Coimbra, Portugal
>>
>>
>>
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>
>
>
> --
> Makoto Miyakoshi
> JSPS Postdoctral Fellow for Research Abroad
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego



-- 
Makoto Miyakoshi
JSPS Postdoctral Fellow for Research Abroad
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego