Validate the ERPAC method for event-related phase–amplitude coupling

Determine whether the event-related phase/amplitude coupling (ERPAC) method introduced by Voytek et al. accurately measures transient phase–amplitude coupling when analyzing phase–amplitude relations with respect to stimulus onset, specifically whether it functions as intended to avoid event-related artifacts.

Background

The paper highlights that non-stationary inputs can induce spectral correlations that mimic cross-frequency coupling (CFC), complicating interpretation. A recently proposed event-related approach (ERPAC) aims to quantify phase–amplitude coupling time-locked to events to avoid such artifacts.

However, the authors express doubt that ERPAC achieves this goal under realistic conditions and refer to supplementary analyses demonstrating scenarios where event-related non-stationarities can still yield spurious results. They argue that resolving this uncertainty ultimately requires formal causal analyses of spectral variables across bands.

References

Whereas ideally, their approach of analyzing phase-amplitude relations with respect to the stimulus onset should avoid some event- related artifacts, it is questionable whether the marker actually works as intended (see Supplementary results: Phase-amplitude coupling for event-related potentials). Ultimately solving these questions requires a formal causal analysis between the spectral variables of different bands (see also Supplementary discussion: Causality methods).

— Untangling cross-frequency coupling in neuroscience (1405.7965 - Aru et al., 2014) in Main text, Section 'Non-stationarity and spectral correlations: two sides of the same coin'