The Laboratory of Neuroethology of Locomotion studies the neurobiology of locomotion: How do nervous systems generate coherent muscle activity to propel animals in their environment? In particular, we focus on the levels of neuronal circuits coordination in the locomotion of the nematode, C. elegans. This 1-millimeter-long roundworm moves through its environment by counteracting muscle contractions activated by a nervous system, as do all other animals, while also using the same molecular and cellular mechanisms, such as neurotransmitters and neuromodulators. Moreover, it offers several advantages as a research model: its nervous system is compact and includes only 302 neurons; it is small and transparent and fits under a microscope; and it is the only animal whose genome and nervous system have been completely mapped. This allows us to use a combination of optical methods to record and control neuronal activity together with transgenic methods to direct these tools to their targets. We use focused laser light to precisely dissect neuronal processes to study the circuit response to injury and regeneration and high-resolution techniques to map neuronal connectivity. More broadly, our research goal is to determine rules that govern the connectivity, activity and robustness of neuronal networks that generate behavior.