LEE, M.J.; Idaho State University: Visual Projections into the Brainstem of Rana pipiens

The goal of this project is to identify the anatomical projections of visual neurons into the frog brainstem. Using 3000MW fluorescent dextrans and Sulforhodamine 101 (SR 101), a voltage activated dye, it was found that labeling the optic nerve yielded staining of the Purkinje cells in the cerebellar cortex, reticular formation neurons, and the trigeminal, hypoglossal, glossopharyngeal, and raphe nuclei. It was also found that visual neurons monosynaptically project onto hypoglossal motor neurons and preliminary evidence suggests polysynaptic projections to the other stained regions. This provides anatomical evidence for visual afferents to directly interact with the underlying neuronal circuitry for feeding behavior as previously shown in R. pipiens . These data are combined with previous work on olfactory projections into the frog brainstem. Unlike the diffuse projections of visual neurons, olfactory afferents only showed monosynaptic projections onto the trigeminal nuclei. These studies demonstrate direct, feed-forward projections of primary sensory afferents into the frog brainstem and the potential for integration of visual and olfactory neurons into the frog feeding motor pattern generator.