[Eeglablist] Questions about ICA component rejection in EEGLAB

[Liu Pan]

Hi Arno,

Thanks for your reply! But the function mentioned in your paper is to
reject ICA components (not epochs); whereas the function "*Tools > Reject
data using ICA > Reject data (all methods)" *is to reject epochs/trials
based on ICA activities, not components, right? Or did I miss anything on
this function?

Thanks for your clarification! Pan



On Mon, Feb 25, 2013 at 11:51 PM, Arnaud Delorme <arno at ucsd.edu> wrote:

> Dear Liu,
>
> (1) yes, the menus are greyed out but to tell the truth, they have always
> been. This is not the function that is referred to in the paper you
> mentionned. The function corresponds to the menu "Tools > Reject data
> epochs > Reject data (all methods)" and "Tools > Reject data using ICA >
> Reject data (all methods)"
>
> Arno
>
> On 25 Feb 2013, at 18:32, Makoto Miyakoshi wrote:
>
> Dear Liu,
>
> (1) I've never noticed them until I confirmed it now. You are right, they
> are grayed out. They are not available from GUI at least, and I don't know
> if there are off-GUI functions for them.
>
> (2) Plot - Component ERPs runs pop_envtopo() where you can evaluate
> percent variance accounted for (pvaf) and related measures that tell you
> each IC's contribution to scalp ERPs. ICs with lower numbers have high
> variance since they are sorted so after ICA. For example your IC90-IC100
> would not have even 1/10 of variance of IC1 (could be even 1/100 which is
> 40dB smaller in FFT plot). This means that discarding 50 out of 100 ICs
> does not mean discarding 50% of data (variance). If you want to measure how
> much 'data' are rejected, you may check pvaf as one of measures.
>
> Makoto
>
> 2013/2/25 Liu Pan <pliu261 at gmail.com>
>
>> Dear eeglabbers,
>>
>> I have 2 questions about the ICA component rejection function of EEGLAB:
>>
>> (1). I read the paper "Automatic artifact rejection for EEG data using
>> high-order statistics and independent component analysis" by Drs. Delorme,
>> Makeig, and Sejnowski.
>> http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=2&ved=0CEAQFjAB&url=http%3A%2F%2Finc.ucsd.edu%2Fica2001%2F117-delorme.pdf&ei=JakrUbjhCMe30gHevIGoCQ&usg=AFQjCNGwjRtjnTiRvUxguqJNAejvoD6a7g&sig2=9BQuz03YEzUOszEreafYgA
>> In *section3.3 *the authors mentioned that in addition to manually and
>> visually rejecting ICA components based on the component properties, there
>> is a function in EEGLAB software by which one can set an adequate rejction
>> threshold for three high-order statistical measures (the entropy of the
>> activity of the component, the kurtosis of the activity, and the kurtosis
>> of the components' spatial map), then one can automatically detect and
>> reject components (insteady of mannually doing so). In search of this
>> function in EEGLAB, I found that in the *Tools--Reject data using
>> ICA--Reject components by map* function, there are 3 buttons at the
>> bottom of the popped out window (*set threshods, see comp. st..., see
>> projection)* which appear to be grey and inactive. I suppose these
>> buttons, especially the on *set threshods, *are relevant to the
>> automatic ICA component rejection function mentioned in that paper.
>>  However, these buttons are not active and cannot be used. According to the
>> *Help* file of this function, *"if the function POP_REJCOMP is ran prior
>> to this function, some fields of the EEG datasets will be present and the
>> current function will have some more button active to tune up the automatic
>> rejection."*  I searched *POP_REJCOMP* function but failed to get a clue
>> from the tutorial nor the previous discussion list. Could anyone give me
>> any suggestion about this? Are these inactive buttons the ones for
>> automatic ICA component rejection?  If yes, how can I get them to work?
>>
>> (2). While doing ICA component rejection, how many of the original
>> components would you reject? I sometimes rejected almost half of them, is
>> it too much or not?
>>
>> Thank you very much for any of your input in advance! Pan
>>
>> --
>> Liu Pan, PhD. Candidate
>> Neuropragmatics and Emotion Lab (Pell Lab)
>> School of Communication Sciences and Disorders
>> Faculty of Medicine, McGill University
>> Montreal, Canada
>>
>>
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>
>
>
> --
> Makoto Miyakoshi
> JSPS Postdoctral Fellow for Research Abroad
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
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-- 
Liu Pan, PhD. Candidate
Neuropragmatics and Emotion Lab (Pell Lab)
School of Communication Sciences and Disorders
Faculty of Medicine, McGill University
Montreal, Canada
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