Neural systems have evolved to close the sensory-motor loop in behaving animals, faced with a variety of tasks. To identify the basic neural architectures, control mechanisms and their plasticity, it is instructive to consider the system in context, from neural circuits and physiology, through the embodiment and physical aspects of behavior, to state dependent plasticity during natural behavior. Our lab has taken this systems approach, combining insight from the theory of dynamical systems, soft matter physics and computational neuroscience to address questions in sensory perception, locomotion and decision making in C. elegans during spontaneous locomotion and in response to sensory stimulation. Approaches used in our lab include locomotion assays in two and three dimensions, microfluidics, calcium imaging and genetics as well as mathematical and computational modeling.