[Eeglablist] removing eye blinks from 256 channel EEG

[Makoto Miyakoshi]

Dear Jeff,

> My epochs range from 3 to 20 minutes.

Sounds too short for 256ch decomposition. You need at least > 1 million
datapoints for it. Using high sampling rate such as 1000Hz increases
apparent datapoints, but I'm not sure how it helps.

> I generally find 1-3 ICs for each subject.

This sounds too few for 256ch decomposition.

> general background noise goes UP after these 1-3 components are removed.

If the removed components are coupled with other components that cancels
out each other, this could happen. However that's kind of rare and I don't
see it very often... most likely your decomposition has problems.

Makoto

On Wed, Nov 26, 2014 at 3:18 PM, K Jeffrey Eriksen <eriksenj at ohsu.edu>
wrote:

>  EEGlabbers:
>
>  Does anyone out there have particular experience from removing eye
> blinks from 256 channel EEG data using ICA? I have started to apply it to
> 11 subjects with data recorded at 1,000 frame/sec, bandpass filtered &
> downsampled to 250 fps. My epochs range from 3 to 20 minutes. I generally
> find 1-3 ICs for each subject. When I remove these, there is still visible
> remnants around the time of each eye blink. Of more concern is that the
> general background noise goes UP after these 1-3 components are removed.
>
>  Any ideas that might improve my results? I can post some screenshots if
> need be.
> Thanks,
>
>  -Jeff
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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