[Mne_analysis] extracting high frequency broadband (HFB) envelope

[Guillaume Corlouer]

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Hello,

I want to perform event related analysis on some high frequency amplitude of some ECoG signals.

I apply raw.filter() and raw.apply_hilbert(envelope=true) in the frequency band of interest on my initial data.

The resulting HFB envelope contains only positive values, as an amplitude should.

Strangely once I epoch the envelope with mne.epoch() using some equally spaced stimulus releated events, the resulting epochs contain some negative value in their entries. But is does not seems that epoching shift the origin x axis or does it?

I know that I can also extract the envelope directly from epoched data but this a confusing observation and would appreciate some explanation of what could go wrong if anybody has 🙂

Cheers,

Guillaume Corlouer

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