Brain-wide representations of olfactory behavior in C. elegans

Abstract:
Olfactory navigation emerges from dynamic interactions among sensory input, brain activity, and the animal’s own movements. In C. elegans, a compact nervous system enables brain-wide imaging in behaving animals exposed to controlled olfactory environments, and undulatory locomotion reduces navigation to transitions among forward runs, reversals, and turns. Here, we used brain-wide tracking microscopy to record neural activity in freely crawling worms navigating spatial odor gradients or isotropic environments, and in immobilized worms responding to temporal odor pulses. Across conditions, we identified strongly correlated brain-wide activity patterns spanning olfactory sensory neurons, interneurons, and premotor neurons. Motor-state transitions and brain-wide correlation structure differed between freely moving and immobilized animals, demonstrating that olfactory sensory representations depend jointly on sensory input, motor activity, and behavioral context. Together, these findings show that brain-wide representations of olfactory behavior are extensively reconfigured by sensory input, self-motion, and behavioral context.