[Eeglablist] Similar ICA components

Tarik S Bel-Bahar tarikbelbahar at gmail.com
Wed Oct 11 12:51:59 PDT 2017

Hello Mahsa, some quick notes below, best wishes.

***********NOTES for Mahsa

Make sure before ICA that after rereferencing...
that you are either A) dropping rank or B) dropping any one channel to fix
rank. Google this topic on eeglablist.
Also check to make sure you are doing your pre-ICA cleaning of the data
Redo your ICA and then let the list know if your double ICs disappeared plz.

You may/could merge the ICs, or focus only on one that has the strongest
across-trial activity. Google some past eeglab list notes on your similar
It's important to fully review and compare the properties of those ICs.

Note you may also be getting such double ICs because of modifications to
the channels during the recording (e.g., moving the channels to fix

Note that there are also caveats on using 32 channel data for ICA, which is
much happier with 64+ electrodes that adequately cover/sample the whole
You may want to just focus on isolating artifactual ICs, removing those,
and then doing your data analysis on channel-level data.
This topic/question has also been mentioned on the list multiple times.

On Mon, Oct 9, 2017 at 11:17 AM, mahsa shalchy <mahsa.shalchy at gmail.com>

> Dear Experts,
> I collected some data using Biosemi system (32 channels) and after doing
> pre-processing steps (resampling, filtering, re-referencing), I epoched the
> data and applied ICA.
> My problem is that, I'm getting two similar components in my ICA results
> (IC3 and IC4).
> I uploaded related images here:
> https://www.dropbox.com/sh/etjkwjrse12lu5j/AABpJvKmKWY5n69eER1GrPGka?dl=0
> Could you please help me with this?
> Many thanks,
> Mahsa
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