[Eeglablist] Questions about ICA component rejection in EEGLAB

[Liu Pan]

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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