Hysteresis plots highlight cross-frequency coupling in EEG analysis of narrative comprehension

Characterizing the dynamic relationships between oscillatory frequency bands is increasingly
prioritized in brain research. Visual representations of complex data can expand the potential for
intuitive and meaningful interpretations. Hysteresis plots are often used in the fields of physics
and engineering, and capture change over time in dynamically interacting variables. Because
they represent and highlight the lag between an influential force and responsive changes, these
plots are especially appropriate for visualizing the interactions hypothesized in cross frequency
coupling; time-lag is considered intrinsic to the mechanism that couples neuronal cell
assemblies.

In this time-frequency EEG study, we use hysteresis plots to illustrate the dynamic coupling of
oscillatory frequencies during visual narrative comprehension. To explore how frequency bands
interact over the course of narrative processing, we plotted hysteresis curves of power over time
in several different frequency-band pairings. Our application of hysteresis visualizations to the
cognitive process of story comprehension yields insight into the poorly understood relationship
between alpha and low-beta suppression, as well as highlighting the contrast between lower-
frequency couplings and those slower rhythms that influence gamma band activity.