[FieldTrip] Phase coherence analysis

[Christina Vanden Bosch der Nederlanden]

Dear FieldTrip!

My team is working on a project where we are trying to see if phase
coherence is calculated while people listen to a busy scene with 4 sounds
playing at the same time. We wanted to examine whether the sound
participants were told to listen to (attended) had greater phase coherence
between the EEG signal and the attended sound's envelope compared to
coherence between the EEG signal and the other, non-attended, sounds in
the scene.

Is it a violation of the assumptions of the ft_connectivity analysis
pipeline I use to calculate phase coherence if I calculate phase coherence
1) on a single trial basis and 2) multiple times using the same EEG signal
but different envelopes of the sounds in the scene? Of course, we still
have 100s of trials (500-700), but the goal is to log the phase coherence
values for each trial and each pairing for the envelope's peak frequency
(all the sounds have different peak modulation frequencies, they are not
just speech sounds) and group the data at a later time according to
coherence (at each stimulus' peak mod freq) for attended and unattended,
perhaps calculated as a difference score from when that envelope was
attended or not.

I know the phase coherence metric evaluates the consistency of coherence at
particular frequencies across trials of the same or similar stimuli, but we
really can't do that here since the peak frequencies are so different
across each stimulus type. So I am wondering if there are big issues with
calculating the data on a single trial basis and grouping the data after
that.

Thanks for your insights!

Christina
-- 
Christina M. Vanden Bosch der Nederlanden
Assistant Professor
Department of Psychology
University of Toronto Mississauga
christinavb at gmail.com
Website: https://www.utm.utoronto.ca/lamalab/
<https://sites.google.com/view/christinavbdn>
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