[Eeglablist] ICA and eye blink component

[bjj2909102003]

Thank you very much, Mr Marco!
Regard to  EEGLAB's rejection methods, I admit it is thorough. However, in cognitive neuroscience research papers  I ofen see "Rejecting extreme values" is used and other rejection methods(abnormal trends, improbable data and abnormal spectra) were less. And for me, "Rejecting extreme values"   is used after rejecting blink with ICA. 



bjj2909102003
 
From: Marco Buiatti
Date: 2014-08-06 16:35
To: bjj2909102003
CC: eeglablist
Subject: Re: Re: [Eeglablist] ICA and eye blink component
Dear Booer,

even though it's time consuming, my advice is:
- to find a way to reject very noisy segments of data BEFORE applying ICA (for example using EEGLAB's rejection methods and tuning the threshold to be as good as possible for all your subjects)
- to review ICA components marked as artefacted by ADJUST or any other method you want to use before blindly accepting automatic classifications.
In my experience, the time spent in cleaning the data is paid back by much clearer results in the analysis!

Best,

Marco


On 6 August 2014 09:22, bjj2909102003 <bjj2909102003 at 163.com> wrote:
Thank you for replying.
Actually, before I run ICA, I only filter the data by bandpass filter. It takes too much time to reject some non-stereotypical artifacts, especially when I got many subjects(~100) data.
It is painful by visual inspection one by one. Your advice is good. Nonetheless, I believe ICA is robust in many situations.

Thanks!
Booer


bjj2909102003
 
From: Marco Buiatti
Date: 2014-08-06 14:53
To: bjj2909102003
CC: eeglablist
Subject: Re: [Eeglablist] ICA and eye blink component
Dear Booer,

blinks are usually well identified by ICA. You may not easily identify blinks if:
1) your subject blinks really a few times -> not enough for being captured by ICA, you may just discard the few epochs containing the blinks;
2) when your subject blinks, s/he moves so much that the relative artifact spreads over most sensors, and ICA is not able to capture it in a few clear components  -> Also in this case my advice is to  discard the epochs containing the blinks;
3) you are computing the ICA on noisy data -> reject segments of your data containing non-stereotypical artifacts and compute the ICA again.

ADJUST works well only if the ICA is computed on clean enough data.

Refs:
On blinks: Croft, R., & Barry, R. (2000). Removal of ocular artifact from the EEG: A review. Clinical Neurophysiology, 30, 5–19.

On removing blinks with ICA:  Jung, T.-P., et al. (2000). Removing electroencephalographic artifacts by blind source separation. Psychophysiology, 37, 163–178.

On removing blinks with ADJUST: Mognon A, Bruzzone L, Jovicich J, Buiatti M, ADJUST: An Automatic EEG artifact Detector based on the Joint Use of Spatial and Temporal features. Psychophysiology 48 (2), 229-240 (2011).

Hope this helps,

Marco




On 5 August 2014 08:53, bjj2909102003 <bjj2909102003 at 163.com> wrote:
Hello,
I want to use ICA to reject eye blink. But for some subjects it is easy to find eye blink component, for others  it is hard to find blink component even I use the plugin-ADJUST. So does ICA extract eye blink component without fail??

Thanks so much!
Booer




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-- 
Marco Buiatti, PhD

CEA/DSV/I2BM / NeuroSpin
INSERM U992 - Cognitive Neuroimaging Unit
Bât 145 - Point Courrier 156
Gif sur Yvette F-91191  FRANCE
Ph:  +33(0)169.08.65.21 
Fax: +33(0)169.08.79.73
E-mail: marco.buiatti at gmail.com
http://www.unicog.org/pm/pmwiki.php/Main/MarcoBuiatti

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-- 
Marco Buiatti, PhD

CEA/DSV/I2BM / NeuroSpin
INSERM U992 - Cognitive Neuroimaging Unit
Bât 145 - Point Courrier 156
Gif sur Yvette F-91191  FRANCE
Ph:  +33(0)169.08.65.21 
Fax: +33(0)169.08.79.73
E-mail: marco.buiatti at gmail.com
http://www.unicog.org/pm/pmwiki.php/Main/MarcoBuiatti

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