[Eeglablist] Do ICs have locations?
guanw at rhpcs.mcmaster.ca
Mon Sep 20 13:28:31 PDT 2010
Thank you for explaining ICA for me. So, each of ICA maps in 2D shows the
percentage of contribution from each channel made to a particular IC.
On Mon, 20 Sep 2010, Ronald Phlypo wrote:
> 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
> Hope this helps,
> Le 16/09/2010 16:51, Weiguang Guan a écrit :
>> 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?
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