Two Types of Rhythmical Jaw Movements Produced by Mechanical Stimulation of the Oral Cavity

Mastication consists of coordinated movements of the jaw, tongue and cheek . The rhythm and pattern of three-dimensional jaw movements in mastication are thought to be generated by the central pattern generator (CPG) in the brain stern1,2). The CPG can be activated by stimulation of various central regions3-6) without feedback information from the peripheral sensory organs2,7,8). On the other hand, it has been demonstrated that mechanical stimulation of oral tissue can evoke a rhythmical jaw movement (RJM) resembling mastication in various mammals9-16) , although to our knowledge there have been no reports describing the pattern of the peripheral induced RJM . The purpose of the present study was to elucidate the pattern of the RJM using the electromyographic (EMG) activities of masticatory muscles evoked by oral mechanical stimulation.