[Eeglablist] the formular to reconstruct data from ICs

[xian zhang]

Dear EEGlab:

supose I only use some goodIC to reconstrust data

is this formula right?
data=eeg.icawinv(:,goodIC)*eeg.icaact(goodIC,:)

the result looks right but how do I use EEG.icasphere in this formula?

Appreciate  your help

Xian
Columbia fMRI research center


>> from an old EEGLAB  email
Yes, it can be used. No, it cannot be used without error (meaning
expecting that (EEG.icawinv*EEG.icaweights*EEG.icasphere)*EEG.data
recovers the original data). The reason is that the number of dimension
is reduced by PCA before running ICA and there is no way you can recover
the information lost when performing this transformation.

You can still visualize the component scalp topographies and they are
meaningful (you simply obtained them applying ICA not on the data but on
a PCA reduction of the data).

Best,

Arno

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