Using the Raspberry Pi Virtual Reality (PiVR) System to Study Larval Chemotaxis with Real and Virtual Odor Gradients.

Here, we present a detailed protocol for the study of the orientation behavior of larvae of the fruit fly in response to both real and virtual odors (chemotaxis). An element common to the study of navigation directed by all sensory modalities is the need to correlate changes in behavioral states (e.g., crawling and turning) with temporal changes in the stimulus preceding these events. It has been shown recently that virtual odor landscapes, with any arbitrary geometry, can be created by combining a platform known as "Raspberry Pi virtual reality" (PiVR) with optogenetics. This methodology offers a technical foundation with which to characterize how the larval nervous system responds to stimulation by real and virtual odors. Furthermore, the experimental steps presented and discussed herein highlight important considerations that are needed to ensure experimental reproducibility. Finally, we believe that this framework can be easily adapted and generalized to allow investigators to study other sensory modalities in the larva and in other animals.