Meeting Abstract
P2.54 Friday, Jan. 4 The function of the submentalis muscle during neuromechanical control of feeding movement in Bufo marinus ROBISON, A*; MANDAL, R; PULJAN, D; ANDERSON, C; Brigham Young University – Idaho; Idaho State University; Idaho State University; Idaho State University andecurt@isu.edu
In our lab, we are using feeding in amphibians as a model system for the neuronal regulation of coordinated movement. During feeding, every striated muscle in the body must be timed in order to accurately position the body, head and tongue onto a prey item. In this continuing study, we have used the Marine Toad, Bufo marinus, to identify the neuronal basis for coordinated feeding movements. Prior research has suggested that precise activation of the muscles requires �pre-load� of the head, jaw and tongue muscles and that there is a muscular �trigger� that signals and initiates the brainstem coordination of muscular activation. Previous studies have also suggested that tongue activation is a ballistic movement and that once begun, is under inertial control and not subjected to on-line modulation. One hypothesis is that the ballistic trigger for coordinating mouth opening and tongue protraction may be the submentalis muscle, a small distal muscle in the lower jaw. In this study we identified the innervation of this muscle, and investigated how sensory afferents, activated as a result of muscular activity, are neuroanatomically connected in the brainstem and spinal cord. A kinematic analysis following denervation of the submentalis produced deficits in the ability to completely protract the tongue. However, the toads were able to account for these deficits in successive trials and could fully protract the tongue within 5-6 attempts. Further, we have identified the location and distribution of the trigeminal nucleus innervating the submentalis, but also have identified a large population of hypoglossal motor neurons that also travel in the mandibular branch of the trigeminal nerve and innervate the submentalis.
