Animals integrate multisensory cues and produce motor outputs resulting in essential behaviors such as predator avoidance or orienting to a stimulus.  The optic tectum, and its mammalian homolog, the superior colliculus, serve as an interface for adaptive sensorimotor processing across vertebrate species.  The mechanisms regulating the development and plasticity of the midbrain circuitry underlying these essential functions are not well understood.  We propose to investigate visual experience-dependent structural and functional plasticity of the development of midbrain circuitry in Xenopus tadpoles and to evaluate circuit function using a visual avoidance assay.  We will use in vivo imaging, electrophysiology and behavior to identify and evaluate circuit components and their plasticity in response to visual experience.  The proposed research should fill this gap in our knowledge and reveal the role of early sensory experience in the development of highly conserved midbrain circuitry.