[Eeglablist] ICA and signal phase content

[otte georges]

Dear ICA experts

 

There is some discussion going on about the evidence that reconstructing an
multichannel EEG after ICA decomposition and removing one or two artefact
components could result in  scrambling the phase content (and coherence) of
the reconstructed signals. Fi starting from a 19 ch EEG, removing two
components with fi electrode pops and sweat artefacts , reconstructing the
19 ch EEG from 17 components (taking out the artefact containing ones)
without those artefacts. 

 

Others say that this is not the case and that ICA respects the phase.
However many authors (Zeman, Thatcher..) have published very convincing data
to the contrary.

 

Any suggestions how to evaluate this ? Is it known from the algorithm what
the reconstruction  will do to the phase content (imaginary part of the
signal) ?

 

All help is very welcome

 

Sincerely

 

Georges

 

 

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