[FieldTrip] problem with ICA
Hwee Ling Lee
hweeling.lee at gmail.com
Thu Jan 16 16:09:13 CET 2014
Thanks for suggestion. Actually, prior to running ICA, I did a notch filter
of 50 Hz and also to remove cardioballistic effects based on the ECG
Does it consider to be mixing the channels?
On 16 January 2014 13:54, Eelke Spaak <eelke.spaak at donders.ru.nl> wrote:
> Hi Hweeling,
> To add to Aaron's explanation, you can instruct the algorithm to use a
> subspace projection of your data by specifying cfg.runica.pca = N,
> where N is the rank of your data (in your case 119, it seems).
> On 16 January 2014 13:42, Aaron Schurger <aaron.schurger at gmail.com> wrote:
> > Sounds like you may have done something to your data, like
> > interpolating channels, before you ran ICA. It is OK to filter your
> > data before running ICA, and some other operations are OK too, but if
> > you do anything that mixes activity from different channels in any
> > way, then you can run into problems with ICA (and results from ICA can
> > be invalid).
> > Aaron
> > On Thu, Jan 16, 2014 at 1:22 PM, Hwee Ling Lee <hweeling.lee at gmail.com>
> >> Dear all,
> >> I've collected data using a 128 channel EEG cap, and I tried to perform
> >> on the data. However, I got an error message with fieldtrip on Matlab.
> >> Here's the error message:
> >> the input is raw data with 127 channels and 1 trials
> >> selecting 123 channels
> >> baseline correcting data
> >> scaling data with 1 over 148.247820
> >> concatenating data.
> >> concatenated data matrix size 123x2789000
> >> starting decomposition using runica
> >> Input data size [123,2789000] = 123 channels, 2789000 frames/nFinding
> >> ICA components using logistic ICA.
> >> Decomposing 184 frames per ICA weight ((15129)^2 = 2789000 weights,
> >> learning rate will be 0.001, block size 75.
> >> Learning rate will be multiplied by 0.9 whenever angledelta >= 60 deg.
> >> More than 32 channels: default stopping weight change 1E-7
> >> Training will end when wchange < 1e-07 or after 512 steps.
> >> Online bias adjustment will be used.
> >> Removing mean of each channel ...
> >> Final training data range: -3.46556 to 6.39436
> >> Computing the sphering matrix...
> >> Starting weights are the identity matrix ...
> >> Sphering the data ...
> >> Beginning ICA training ...
> >> Data has rank 119. Cannot compute 123 components.
> >> the call to "ft_componentanalysis" took 148 seconds
> >> Could someone please let me know what went wrong?
> >> Thanks!
> >> Cheers,
> >> Hweeling
> >> _______________________________________________
> >> fieldtrip mailing list
> >> fieldtrip at donders.ru.nl
> >> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> > --
> > Aaron Schurger, PhD
> > Senior researcher
> > Laboratory of Cognitive Neuroscience
> > Brain-Mind Institute, Department of Life Sciences
> > École Polytechnique Fédérale de Lausanne
> > Station 19, AI 2101
> > 1015 Lausanne, Switzerland
> > +41 21 693 1771
> > aaron.schurger at epfl.ch
> > http://lnco.epfl.ch/
> > _______________________________________________
> > fieldtrip mailing list
> > fieldtrip at donders.ru.nl
> > http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
Dr. rer. nat. Lee, Hwee Ling
German Center for Neurodegenerative Diseases (DZNE) Bonn
Email 1: hwee-ling.lee<at>dzne.de
Email 2: hweeling.lee<at>gmail.com
Ernst-Robert-Curtius Strasse 12, 53117, Bonn, Germany
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