Navigational strategies underlying temporal phototaxis in Drosophila larvae

Navigating across light gradients is essential for survival for many animals. However, we still have a poor understanding of the algorithms that underlie such behaviors. Here, we developed a novel closed-loop phototaxis assay for Drosophila larvae in which light intensity is always spatially uniform but updates depending on the location of the animal in the arena. Even though larvae can only rely on temporal cues during runs, we find that they are capable of finding preferred areas of low light intensity. Further detailed analysis of their behavior reveals that larvae turn more frequently and that heading angle changes increase when they experience brightness increments over extended periods of time. We suggest that temporal integration of brightness change during runs is an important - and so far largely unexplored - element of phototaxis.

Automated summary

The researchers developed a novel closed-loop phototaxis assay for Drosophila larvae to study their navigation behavior in light gradients. They found that larvae are able to find preferred areas of low light intensity during runs, even when relying on temporal cues. Further analysis revealed that larvae turn more frequently and change heading angles more when experiencing brightness increments over extended periods of time, suggesting that temporal integration of brightness change is an important element of phototaxis.