Meeting Abstract

P2.63  Friday, Jan. 4  Integration of hypoglossal, glossopharyngeal and trigeminal neurons within the brainstem of marine toad, Bufo marinus MANDAL, R*; ANDERSON, CW; Idaho State University; Idaho State University andecurt@isu.edu

The goal of our research is to investigate the neural integration coordinating feeding movements in toads (genus Bufo). The basic neural circuits that mediate rapid ballistic tongue projection are reasonably well characterized in the leopard frog, Rana pipiens. While the biomechanics of tongue protrusion are functionally similar in intact toads and frogs, long protrusible tongues have independently evolved between these two groups and the neural circuits in the brainstem have not been well described in Bufo. Our recent research with denervation of the trigeminal nerve suggests that jaw opening and tongue protrusion rely on interactions between sensory fibers from trigeminal and hypoglossal peripheral nerves prior to mouth opening. In this study, the peripheral hypoglossal nerve was labeled to first identify the distribution of the hypoglossal motor nuclei and the sensory projections. Secondly, the hypoglossal and glossopharyngeal nerves were labeled to identify convergence of these neurons in the reticular formation of the medulla. Finally, the trigeminal and hypoglossal nerves were double labeled to identify the convergence in the brain stem and the possible locations for the coordination of jaw and tongue movements. This information will be combined with future studies to try to identify the pre-motor neurons and interneurons coordinating muscle activity during feeding in toads.