Motor and Sensory Cortical Processing of Neural Oscillatory Activities revealed by Human Swallowing using Intracranial Electrodes

Swallowing is a unique movement because orchestration of voluntary and involuntary movement, and coordination between sensory input and motor output are indispensable. We hypothesized that neural mechanism of them were revealed by cortical oscillatory changes. Eight epileptic participants fitted with intracranial electrodes over the orofacial cortex were asked to swallow a water bolus, and cortical oscillatory changes were investigated. At the boundary time between voluntary and involuntary swallowing, high {gamma} (75-150 Hz) power achieved the peak, and subsequently, the power decreased. High {gamma} power increases (burst) were associated with both sensory input and motor output. However, phase-amplitude coupling (PAC) revealed that sensory-related coupling appeared during high {gamma}-bursts, and motor-related coupling appeared before high {gamma}-bursts. The peak of high {gamma} power suggests switching of swallowing driving force from the cortex to the brain stem, and PAC findings suggest that motor-related coupling induces later motor-related high {gamma}-activities representing endogenous neural processing.