[Eeglablist] How to deal with corrupted ICA decompositions

Arnaud Delorme arno at ucsd.edu
Fri Jan 30 09:46:45 PST 2015

The data was not full rank but necessary corrections were done (PCA of number of channels-1). Full rank is a common issue though and one that should be checked first.

This is another problem which might be specific to the EEG amplifier and to Infomax ICA in which the first two components become quite noisy.


On Jan 29, 2015, at 5:30 PM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu> wrote:

> Arno, check if your original data was full rank. I've repeatedly seen this before, and I found it happens when the data are not full ranked. By the way, when you run matlab rank() don't use too long data, just give it short data long... you may also want to test it by changing the length (1:1000, 1:10000, 1:100000...) In the middle of this wiki page http://sccn.ucsd.edu/wiki/Makoto%27s_preprocessing_pipeline I put an example of such case. 
> Makoto
> On Tue, Jan 20, 2015 at 3:03 PM, Arnaud Delorme <arno at ucsd.edu> wrote:
> I have recently added a small section to the EEGLAB wiki that deals with working with ICA decomposition where the two first components activity is extremely noisy (which seems to be a bug of Infomax). This does not happen often, but I thought I should share it with the list.
> http://sccn.ucsd.edu/wiki/Chapter_09:_Decomposing_Data_Using_ICA#How_to_deal_with_.22corrupted.22_ICA_decompositions
> Arno
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> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego

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