Navigating chemical landscapes: Using microfluidic devices to create complex plumes.

Although the ability to use environmental chemical cues for navigation is crucial and evolutionarily conserved across all species, we still poorly understand which features animals use to find odor sources. This is primarily because chemical stimuli occur in highly diverse regimes, such as stationary gradients, laminar, or turbulent flow, while tools to control and measure their spatiotemporal dynamics remain limited. We propose to address this gap by combining zebrafish larvae with microfluidics. Zebrafish larvae emerged as a powerful model for behavior and systems neuroscience, thanks to its rich behavioral repertoire, genetic tools availability, optical transparency and small enough for their nares to sit at the chip outlet. We will present the characterization of a PDMS-based microfluidic chip controlled by an electromechanical pressure and flow-control system, enabling olfactory stimuli with precise temporal and concentration control. We demonstrate its ability to reproduce plume-like concentration fluctuations at different spatial locations relative to the odor source and as well as the transition speed between distant points. The system can be integrated with virtual reality and whole-brain imaging, enabling altered feedback experiments to identify which components of plume dynamics are required for navigation toward an odor source. We hope to discuss the goals and strategies of this early stage project with the community.