[Eeglablist] Do ICs have locations?

Ronald Phlypo Ronald.Phlypo at ugent.be
Mon Sep 20 01:06:02 PDT 2010


  Dear Weiguang,

The IC's are obtained through the decomposition of the observations y(t) 
as y(t) = A*x(t), where the x(t) are the estimates of the sources. The 
model could easily be rewritten using vector notation only as y(t) = Sum 
over i of a[i]*s[i], where the a[i] are the column vectors taken from A.

The a[i] thus clearly expose the spatial distribution of the s[i] over 
the scalp (the spatial distributions do not depend on the time and are 
supposed stationary in this model), up to a global scaling factor which 
includes a possible sign change. Moreover, taking a[i]^2 -- which stands 
for the quadratic of each of the elements in the column vector -- 
returns the power distribution of the i-th source up to a global scaling 
factor.

Hope this helps,

Ronald



Le 16/09/2010 16:51, Weiguang Guan a écrit :
> Hello,
>
> I'm new to EEGLAB. I don't think the components after ICA have location
> information associated. If this is true, then how could EEGLAB plot ICs on
> a scalp?
>
> Weiguang
>
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