The Raspberry Pi Virtual Reality system (PiVR) is a versatile tool for presenting virtual reality environments to small, freely moving animals (such as flies and fish larvae), according to a study published July 14, 2020 in the open-access journal PLOS Biology by David Tadres and Matthieu Louis of the University of California, Santa Barbara. The use of PiVR, together with techniques like optogenetics, will facilitate the mapping and characterization of neural circuits involved in behavior.
PiVR consists of a behavioral arena, a camera, a Raspberry Pi microcomputer, an LED controller, and a touchscreen. This system can implement a feedback loop between real-time behavioral tracking and delivery of a stimulus. PiVR is a versatile, customizable system that costs less than $500, takes less than six hours to build (using a 3D printer), and was designed to be accessible to a wide range of neuroscience researchers.
In the new study, Tadres and Louis used their PiVR system to present virtual realities to small, freely moving animals during optogenetic experiments. Optogenetics is a technique that enables researchers to use light to control the activity of neurons in living animals, allowing them to examine causal relationships between the activity of genetically-labeled neurons and specific behaviors.
As a proof-of-concept, Tadres and Louis used PiVR to study sensory navigation in response to gradients of chemicals and light in a range of animals. They showed how fruit fly larvae change their movements in response to real and virtual odor gradients. They then demonstrated how adult flies adapt their speed of movement to avoid locations associated with bitter tastes evoked by optogenetic activation of their bitter-sensing neurons. In addition, they showed that zebrafish larvae modify their turning maneuvers in response to changes in the intensity of light mimicking spatial gradients. According to the authors, PiVR represents a low-barrier technology that should empower many labs to characterize animal behavior and study the functions of neural circuits.
"More than ever," the authors note, "neuroscience is technology-driven. In recent years, we have witnessed a boom in the use of closed-loop tracking and optogenetics to create virtual sensory realities. Integrating new interdisciplinary methodology in the lab can be daunting. With PiVR, our goal has been to make virtual reality paradigms accessible to everyone, from professional scientists to high-school students. PiVR should help democratize cutting-edge technology to study behavior and brain functions."
Peer reviewed; Observational study; Animals
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Citation: Tadres D, Louis M (2020) PiVR: An affordable and versatile closed-loop platform to study unrestrained sensorimotor behavior. PLoS Biol 18(7): e3000712. https://doi.org/10.1371/journal.pbio.3000712
Funding: This work was funded by the National Institute for Health (RO1-NS113048-01) and by the University of California, Santa Barbara (startup funds). This work was also supported by the National Science Foundation under Grant No. NSF PHY-1748958, Grant No. IOS-1523125, IH Grant No. R25GM067110, and the Gordon and Betty Moore Foundation Grant No. 2919.01. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.