Masticatory and Brux-like Motor Patterns in the Freely Behaving Rat: Electromyography and Phase Analysis

Our objective was to develop an experimental platform to examine brainstem commands, and trigeminal neural networks that underlie activation and switching of masticatory and brux-like motor patterns of the jaw. This characterization could help us understand the underlying mechanisms of human bruxism. Sixteen male rats (200-224 g) had EMGs implanted into right superficial masseter (mass: jaw closing, n=16), temporalis (temp: jaw closing, n=8), and anterior digastric (dig: jaw opening, n=8) muscles. We conducted a dual-referent phase analysis in order to assess coordination. We used Rayleigh test to discriminate between uniform and unimodal-clustered phase distributions, and Williams F-test to determine if mean angles differed significantly. We found: 1) Phase differences between jaw closing muscles, the temp and mass (p