[Eeglablist] How to save EOG channels from ASR processing?

[Akshay Kumar]

Thanks for the reply.

Many of the researchers in good journal papers rely on visual examination to eliminate bad channels.

That's a good technique in itself for an experienced EEG researcher.

On the other hand, if I talk about ASR, from your inputs, I believe the better approach would be:

  1.  Save a copy of EEG data say it origEEG.
  2.  Run ASR on EEG.
  3.  See what channels ASR has removed using EEG.etc command (call them bad channels).
  4.  Remove all the non-EOG bad channels from the origEEG manually and interpolate them.
  5.  Perform further analysis using origEEG.

This way we saved EOG channels and removed all the non-EOG bad channels as well.


Thanks,
Akshay
________________________________
From: Tarik S Bel-Bahar <tarikbelbahar at gmail.com>
Sent: Tuesday, October 23, 2018 1:52:52 AM
To: akshayksharma94 at live.com
Cc: eeglablist
Subject: Re: [Eeglablist] How to save EOG channels from ASR processing?

Hello Akshay, brief notes below, best wishes.

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EOG channels are not necessary to keep in for ICA, as frontal EEG channels usually pick up blink ICs easily with out the EOG channels.
Different researchers have different opinions, needs, and biases. Best to rely on high-quality ICA-EEG research papers to decide whether or not you need to retain the EOG channels.
However, you may be needing the EOG channels for some EOG-related analyses you are doing.
The method you describe should work ok. However, note that ASR may include the EOG channels in determining what the bad channels are,
and if you feed it data without the EOG channels, the ASR method may give you different results (test it out to be sure, at different thresholds and with/without EOG  chans).

ASR is one method to remove channels, but be careful it can be too intense (depending n the thresholds you set), or may not fit your study's requirements.
When you can, try to understand the EEG data well enough so that you can determine what the bad channels are yourself by eye.
Note also that there are other methods for bad channel detection in the EEGLAB gui (near the ASR option in the eeglab menu).
Also, remember that Makoto's pipeline recommendations are just (useful) recommendations, and they are meant to orient beginners working with EEGLAB.
Overall, it is important to be able to develop your own pipeline, for good reasons, and ideally using methods from high-quality published EEG papers to guide your decisions.
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