Characterizing chemosensory responses in C. elegans with multi-neuronal imaging

Abstract

How do animals use their sensory neurons to perceive their chemical environment? How does sensory information get transformed by downstream circuits? And ultimately, how do animals generate behavior in response to chemical cues? We set out to understand how the entire C. elegans brain processes chemosensory information. To enable these studies, we developed genetic, experimental, and computational tools which allow for high-throughput acquisition of stimulus-evoked activity in populations of neurons. Observing the dynamics of the chemosensory neurons in response to a broad odor panel, we uncovered numerous previously unreported sensory responses and built a comprehensive picture of the way the chemosensory system in C. elegans encodes odor information. To understand whole-brain responses to chemosensory stimuli, we developed a system which labels every neuron in C. elegans with a multicolor landmark, allowing us to conduct pan-neuronal imaging with comprehensive neuronal identification. We found widespread stimulus-evoked activity across sensory neurons, interneurons, and motor neurons. We examined the relationship between functional activity and the C. elegans connectome, and built connectome-inspired artificial neural network models with pan-neuronal data. The methods we have developed enable new, whole-brain approaches to understanding sensorimotor transformations in C. elegans.