[Eeglablist] removing eye blinks from 256 channel EEG

[K Jeffrey Eriksen]

Makoto,

Thanks for your response. I believe I successfully obtained eye movement components 10-12 years ago with 10 or 11 minutes of 256-channel, 250 sps EEG.

Do you mean I should get more than 1-3 eye movement related components?

What do you suggest to try to improve the decomposition? I know there are some free parameters I could try, but what should I try first?

Thanks,
-Jeff

From: Makoto Miyakoshi [mailto:mmiyakoshi at ucsd.edu]
Sent: Thursday, December 04, 2014 11:33 AM
To: K Jeffrey Eriksen
Cc: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] removing eye blinks from 256 channel EEG

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<mailto: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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