PiVR: an affordable and versatile closed-loop platform to study unrestrained sensorimotor behavior

Tools enabling closed-loop experiments are crucial to delineate causal relationships between the activity of genetically-labeled neurons and specific behaviors. We developed the Raspberry Pi Virtual Reality system (PiVR) to conduct closed-loop optogenetic stimulation of neural functions in unrestrained animals. PiVR is an experimental platform that operates at high-temporal resolution (70 Hz) with low latencies (<30 ms), while being affordable (<$500) and easy to build (<6 hours). Through extensive documentation, this tool was designed to be accessible to a wide public, from high-school students to professional researchers studying systems neuroscience. We illustrate the functionality of PiVR by focusing on sensory navigation in response to gradients of chemicals (chemotaxis) and light (phototaxis). We show how Drosophila flies perform negative chemotaxis by modulating their locomotor speed to avoid locations associated with optogenetically-evoked bitter taste. In Drosophila la...