Assessing circuit function in the developing Xenopus tadpole: a survey of the behavioral toolkit and underlying...

Xenopus laevis has long served as an important model for studies of embryonic development and is a cornerstone to our current understanding of cellular and molecular mechanisms underlying neurodevelopment, including the formation and refinement of neural circuits. In recent years, considerable efforts have been made to leverage the great accessibility and amenability of the Xenopus system to model neurodevelopmental and neurodegenerative disorders in humans for higher-throughput investigations of genetic and environmental risk factors. Behavioral paradigms are indispensable tools to assess functional output in whole animals. In this review, we summarize a range of behavioral paradigms established in Xenopus laevis and Xenopus tropicalis tadpoles to evaluate the functional development of the nervous system. We discuss the current understanding of neural substrates that give rise to specific behaviors, and how these paradigms have been used to evaluate the functional ramifications of cellular and molecular abnormalities in neural circuitry. We cover three categories of behavioral paradigms: innate and stable behaviors, experience-dependent and learned behaviors, and social behaviors. Each provides distinct functional readouts of the developing nervous system. We also include tips and suggestions for the implementation of these paradigms and discuss how insights from other aquatic animal models may inform the further development of behavioral paradigms in Xenopus tadpoles.