PiVR Is a Low-Cost Virtual Reality System — for Fruit Flies, Larvae, and Other Small Animals
Designed for optogenetic experimentation, the 3D-printed PiVR is an immersive virtual reality environment if you're a small enough creature.
A pair of researchers at the University of California at Santa Barbara have created a Raspberry Pi-powered immersive virtual reality (VR) system unlike any other: It's designed for use by small animals like flies and fish larvae.
"Tools enabling closed-loop experiments are crucial to delineate causal relationships between the activity of genetically labelled neurons and specific behaviors," researchers David Tadres and Matthieu Louis explain. "We developed the Raspberry Pi Virtual Reality (PiVR) system 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 milliseconds), while being affordable (<US$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."
The PiVR system is based around a Raspberry Pi single-board computer linked to a camera, an LED controller, and a touch-screen display which shows a user-friendly custom interface. A single PiVR, which is entirely self-contained with no need for an external computer system and which uses a framework built of 3D-printed parts, costs just under $500 to build; the cost drops to around $350 per unit when several are built in parallel, the pair note.
To demonstrate PiVR's capabilities, the researchers set up simple optogenetic experiments with fruit fly larvae, adult fruit flies, and zebrafish larvae — nothing that in all cases the animals behaved as would be expected if they were in a reality matching the virtual one presented by the PiVR system.
"Although PiVR was developed for animals measuring no more than a few centimetres," the researchers note, "it should be easily scalable to accommodate experiments with larger animals such as mice and rats. Together with FlyPi and the ethoscope [earlier Raspberry Pi-powered lab tools], PiVR represents a low-barrier technology that should empower many labs to characterize new behavioral phenotypes and study neural circuit functions with minimal investment in time and research funds."
The team's paper has been published under open-access terms in the journal PLOS Biology; more information, including the source code, can be found on Read The Docs.