[Eeglablist] ICA, re-referencing, interpolation

[Makoto Miyakoshi]

Dear Jumana,

I encountered that kind of situation many times, which is why I thought it
would be a nice idea to show the exact steps in the wiki page. Now you see
my point!

Editing channels after ICA is DANGEROUS. There are even some phenomena that
confused me to death which I still don't understand (and do not remember
well any more). Some of EEGLAB's check function can detect the change of
channel number difference and inconsistency with EEG.ica-items, but not all
the operations are not supported, particualy any behavior outside GUI (but
the worst mysterious case I experienced was replicated even using GUI, so I
guess it was like I was performing bug finding in EEGLAB, as if several
test players plays an alpha version of a computer game trying to do the
weirdest things to find bugs.)

So, my advice is that DO NOT EDIT CHANNELS AFTER ICA. Once the mixing
matrix is confused and how it happened, you are done. Just stay away from
that situation.

I appreciate though you have been doing exploration! I'm glad to see that
at least other guys than I experience the same issues.

>From Lufthansa455 to Frankfurt,

Makoto



On Wed, Jan 4, 2017 at 9:06 AM, Ahmad, Jumana <jumana.ahmad at kcl.ac.uk>
wrote:

> Dear EEGLab,
>
>
>
> I do not include noisy channels in ICA which I only do to remove eye
> related components, and specifically want to interpolate then after ICA for
> rank reasons. I have now done this to over 100 datasets.
>
> However, once I interpolate and then re-reference my data to the average,
> I get the error: Error: some channels not used for ICA decomposition are
> used for rereferencing
>
>        the ICA decomposition has been removed
>
>
>
> However, I purposefully wanted to interpolate these after ICA, and then
> use them for the average.
>
> Is my eye-blink removal via ICA now affected and undone?
>
> I would appreciate any advice.
>
> Best wishes,
>
> Jumana
>
>
>
> *------------------------------------------*
>
> *Jumana Ahmad*
>
> Post-Doctoral Research Worker in Cognitive Neuroscience
>
> *EU-AIMS Longitudinal European Autism Project (LEAP) & SynaG Study*
>
> Room M1.09. Department of Forensic and Neurodevelopmental Sciences (PO 23)
> | Institute of Psychiatry, Psychology & Neuroscience | King’s College
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>
> *Phone:* 0207848 0260| *Email:* jumana.ahmad at kcl.ac.uk
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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