Modular assays for the quantitative study of visually guided navigation in both flying and walking flies.

Background: The quantitative study of behavioral responses to visual stimuli provides crucial information about the computations executed by neural circuits. Insects have long served as powerful model systems, either when walking on air suspended balls (spherical treadmill), or flying while glued to a needle (virtual flight arena).

New Method: Here we present detailed instructions for 3D-printing and assembly of arenas optimized for visually guided navigation, including codes for presenting both celestial and panorama cues. These modular arenas can be used either as virtual flight arenas, or as spherical treadmills and consist entirely of commercial and 3D-printed components placed in a temperature and humidity controlled environment.

Comparison To Existing Method(s): Previous assays often include a combination of rather cost-intensive and technically complex, custom-built mechanical, electronic, and software components. Implementation amounts to a major challenge when working in an academic environment without the support of a professional machine shop.

Results: Robust optomotor responses are induced in flyingDrosophila by displaying moving stripes in a cylinder surrounding the magnetically tethered fly. Similarly, changes in flight heading are induced by presenting changes in the orientation of linearly polarized UV light presented from above. Finally, responses to moving patterns are induced when individual flies are walking on an air-suspended ball.

Conclusion: These modular assays allow for the investigation of a diverse combination navigational cues (sky and panorama) in both flying and walking flies. They can be used for the molecular dissection of neural circuitry in Drosophila and can easily be rescaled for accommodating other insects.