Chewing phase - theta amplitude coupling facilitates working memory

Rhythmic chewing enhances cognitive performance, yet the neural mechanisms linking oromotor behavior to cortical dynamics remain poorly understood, in part due to motion artifacts that obscure brain signals. We used high-density EEG with a custom artifact attenuation pipeline to examine how mastication shapes frontocentral theta oscillations during working memory.Thirty-one participants performed a visuospatial 2-back task under two conditions: at rest and while chewing. Chewing resulted in faster responses and a selective increase in theta power (4-7 Hz) during the late post-stimulus window (900-1300 ms), a phase associated with cognitive control. Theta amplitude was modulated by the chewing phase, revealing strong cross-frequency coupling between motor output and neural oscillations. The strength of this entrainment increased with chewing frequency, indicating a dose-dependent neural gain. Our results demonstrate that peripheral rhythmic activity can synchronize brain rhythms relevant to cognition in real time, supporting a mechanistic link between bodily action and executive function. These findings enhance our understanding of sensorimotor-cognitive integration and point to natural motor rhythms as promising non-invasive tools for modulating brain activity.