Effect of Mastication on Human Brain Activity

Mastication is a complicated movement generated from a neural population in the brainstem and a neural network involving several brain regions. Recently, attention has been focused on the relationship between mastication and age-related decline in human cognitive function, but the neural mechanisms underlying this association remain unknown. In this article, we review research on the effect of mastication based on data obtained using event-related potentials (ERPs), including the P300 component and contingent negative variation (CNV), motor-related cortical potentials (MRCPs), and reaction time (RT) as behavioral data. The peak latency of P300 and RT clearly shortened with the repetition of sessions in Mastication, but not in Control, Jaw Movement, or Finger Tapping. The mean amplitude of CNV differed between the Mastication and Control conditions with the repetition of sessions. By contrast, there was no significant difference in the amplitude of MRCP between Mastication and Control in any of the sessions. These results suggest that mastication is associated with cognitive processing rather than movement-related processing in the human brain. We believe that non-invasive recording methods, such as electroencephalography (EEG), magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), and near-infrared spectroscopy (NIRS), will supply valuable evidence in support of a positive relationship between mastication and cognition.