[Eeglablist] rerun ICA to improve ocular artifacts removal

[Daniela Dentico]

Hi! I was wondering if it does make sense on a theoretical point of view to rerun ICA on
data cleaned from artifacts with a previous ICA if the result is not
satisfactory.



I'm analyzing continuous waking data
(256 channels EEG) from a subject with a huge amount of eyes movements.



Before ICA the topography was
completely dominated by eyes movements. After removing independent components
that isolated ocular artifacts, there was a big improvement, with a 10 times reduction
of the power of ocular artifacts in the theta band for instance. Eyes movements were still there
though.



I tried to run ICA a second time
on the clean data. I'm very doubtful about the quality of this second
decomposition since many source activation time courses (scroll component
activities) look very weird,, with a lot of high frequency activity, as you can see from the enclosed file ('ICactivation') that show the first 10% of the sources activities. I also enclosed a screen shot of the first 8 components of this second run of ICA and a higher magnification image of the continuous data for the first component.

Any cue/suggestion/explanation? 


Thank you!

Daniela

--
Daniela Dentico, MD PhD
Center for Sleep and Consciousness
University of Wisconsin - Madison
6001 Research Park Boulevard
Madison, Wisconsin 53719







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