The purpose of the proposed project is to identify the efferent projections of the accessory optic nuclei in the tegmentum of the rat and bat. The efferent projections of these nuclei (the dorsal tegmental nucleus, the lateral tegmental nucleus, and the medial tegmental nucleus) will be determined by two distinctly different but complementary methods. One method will employ anterograde degeneration techniques following lesions of each nucleus. This will be used to trace the course and the termination of the pathways arising from each of the accessory optic nuclei. The other method will employ autoradiography following intranuclear injections of tritiated proline. This will permit the tracing of the efferent pathways of the accessory optic nuclei in the non-lesioned animal. It is hoped that such a study will clarify the relationship of the accessory optic nuclei to the visual system and also lead to functional inferences that may be tested behaviorally.