CLARK, NL; SHAW, KA; ANDERSON, CW; Idaho State University; Idaho State University; Idaho State University: Convergence of hypoglossal and glossopharyngeal nerve aferents with ing the brainstem of the leopard frog, Rana pipiens

This research investigated the anatomical convergence of sensory input into the brainstem of the leopard frog, Rana pipiens. Using retrograde labeling combined with activity dependent neuronal tracers, sensory projections from the peripheral hypoglossal (XII) and glossopharyngeal (IX) nerves were labeled. The two different labeling techniques were used to determine if XII and IX project to the same cells within the brainstem, specifically the medial reticular formation (RF). Double labeling of IX and XII were also combined with DIC microscopy to verify convergence. In order to demonstrate a direct projection as opposed to activating RF neurons through a cerebellar circuit, the cerebellum was lesioned and the experiments were repeated. Results demonstrate that terminals of IX and XII converge directly onto the same medial reticular formation cells. Experiments done with an intact cerebellum also suggest multiple monosynaptic contacts onto the same Purkinje cells in the cerebellum. These data provide further evidence that afferents from the glossopharyngeal and hypoglossal nerve converge onto the brainstem and onto neurons involved in sensorimotor integration during the neural generation of feeding behavior.