Hidden Brain States Reveal the Temporal Dynamics of Neural Oscillations During Metaphor Generation and Their Role in Verbal Creativity.

We investigated the oscillatory brain processes while people generated metaphors for science concepts. Applying a hidden Markov model, we extracted brain states, representing temporally disentangled oscillatory processes, from EEG data. By associating the trial-by-trial occupancy of brain states with the creative quality, novelty, and aptness of the generated metaphors, we identified oscillatory processes that played a role in creative ideation in a data-driven manner. Metaphor novelty was positively associated with occupancy in a state featuring widespread alpha-band synchronization during the early trial stage and occupancy in a state featuring alpha-band desynchronization during the later trial stage. In addition, metaphor novelty was negatively associated with gamma-band power. Our results not only extend previous literature on the role of oscillatory processes in creative ideation but also highlight the importance of temporal dynamics in understanding the brain mechanisms during sustained cognitive task performance.