[FieldTrip] question about automatic artefact rejection

[De Meyer, Kris]

Dear Fieldtrippers,

In ft_artifact_muscle<http://www.fieldtriptoolbox.org/reference/ft_artifact_muscle>, an EEG signal is first filtered - usually with a bandpass filter with cutoff frequencies of [110,140]. The documentation then says that the hilbert envelope is calculated, after which the envelope values are z-transformed before they are thresholded.

However, is this sound? Whereas the actual filtered EEG values (the result of the bandpass filter) are usually normally distributed, the hilbert envelope values are far from.

What is the rationale for calculating the z-transform of a non-Gaussian distribution? Doesn't that introduce problems?

Best,

Kris





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