Continuous odor profile monitoring to study olfactory navigation in small animals

• Published in: eLife Vol. 12
• Main Authors: Chen, Kevin S, Wu, Rui, Gershow, Marc H, Leifer, Andrew M
• Format: Journal Article
• Language: English
• Published: England eLife Sciences Publications Ltd 25.07.2023; eLife Sciences Publications, Ltd
• Subjects: Animals; Behavior; Behavior, Animal; Caenorhabditis elegans; Chemotaxis; Drosophila melanogaster; Experiments; Insects; locomotion; navigation; Navigation behavior; Neural networks; Neuroscience; odor; Odor control; Odorants; Odors; olfaction; Olfactory pathways; Physics of Living Systems; Sensors; Sensory evaluation; Smell; Spectrum analysis; Tools and Resources; C. elegans; navigation; neuroscience; locomotion; olfaction; odor; D. melanogaster; behavior; physics of living systems; chemotaxis
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.85910

Olfactory navigation is observed across species and plays a crucial role in locating resources for survival. In the laboratory, understanding the behavioral strategies and neural circuits underlying odor-taxis requires a detailed understanding of the animal’s sensory environment. For small model organisms like Caenorhabditis elegans and larval Drosophila melanogaster , controlling and measuring the odor environment experienced by the animal can be challenging, especially for airborne odors, which are subject to subtle effects from airflow, temperature variation, and from the odor’s adhesion, adsorption, or reemission. Here, we present a method to control and measure airborne odor concentration in an arena compatible with an agar substrate. Our method allows continuous controlling and monitoring of the odor profile while imaging animal behavior. We construct stationary chemical landscapes in an odor flow chamber through spatially patterned odorized air. The odor concentration is measured with a spatially distributed array of digital gas sensors. Careful placement of the sensors allows the odor concentration across the arena to be continuously inferred in space and monitored through time. We use this approach to measure the odor concentration that each animal experiences as it undergoes chemotaxis behavior and report chemotaxis strategies for C. elegans and D. melanogaster larvae populations as they navigate spatial odor landscapes.