[A comparative study between cortically induced fictive mastication and actual mastication in acute and chronic...

To explore the mechanism of coordinated jaw, tongue and hyoid movements during mastication, electromyograms of jaw, tongue and hyoid muscles were recorded simultaneously in rhythmic jaw movements during both cortically induced fictive mastication (CIFM) and actual mastication. 1. The jaw movement patterns of different stage of actual mastication were similar with the corresponding basic patterns of CIFM. 2. Masseter, Styloglossus and Sternohyoideus, which were activated mainly in the jaw-closing phase, were facilitated in proportion to the hardness of the chewing materials during both types of mastications. However, digastric, genioglossus and geniohyoideus, which were activated mainly in the jaw-opening phase, were not facilitated in either type of mastication. 3. The modulations of burst durations by hardness of chewing materials were some different between two types of mastications. These results suggested that physiological properties of CIFM are similar to those of actual mastication, and thus CIFM may be used as a model of actual mastication.