[Eeglablist] ICA and eye blink component

[Tyler Grummett]

There was a topic on here in the past about highpass filters and connectivity. It's because the filter uses the future of the signal to calculate the past (or something).

I detrend before ICA for sure.



On 7 Aug 2014, at 1:07 pm, "bjj2909102003" <bjj2909102003 at 163.com<mailto:bjj2909102003 at 163.com>> wrote:

Thank you. But I don't know when the detrend function is used (after run ICA)??And in my view, removing linear trend is equal to high-pass filter.

________________________________
bjj2909102003

From: Tyler Grummett<mailto:tyler.grummett at flinders.edu.au>
Date: 2014-08-07 08:28
To: bjj2909102003<mailto:bjj2909102003 at 163.com>
CC: Marco Buiatti<mailto:marco.buiatti at gmail.com>; eeglablist<mailto:eeglablist at sccn.ucsd.edu>
Subject: Re: [Eeglablist] ICA and eye blink component
Just remember that if you band pass before ICA you can't do directional connectivity with the ICs.

I've found using SIFT's detrend function is a good alternative.

Good luck!

Tyler

On 7 Aug 2014, at 2:25 am, "bjj2909102003" <bjj2909102003 at 163.com<mailto: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<mailto:marco.buiatti at gmail.com>
Date: 2014-08-06 14:53
To: bjj2909102003<mailto:bjj2909102003 at 163.com>
CC: eeglablist<mailto:eeglablist at sccn.ucsd.edu>
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<mailto: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
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