Virtual reality (VR) headsets like Apple Vision Pro and Meta Quest give people immersive experiences of different worlds. Now mice have—MouseGoggles! The perfect VR experience for our rodent friends.

Researchers at Cornell University have developed a tiny set of VR goggles for lab mice, to help study the brains of mice and humans.

These VR goggles allow scientists to provide an immersive experiences for the mice, while simultaneously capturing fluorescent images of their brain activity. The neurons glow when a special calcium dye is injected, and finds its way to neurons (brain cells).

The goggles are very small, yet dwarf the tiny mice in size, and were built using low-cost, off-the-shelf components like OLED smartwatch displays and tiny lenses, researchers said.

“It definitely benefited from the hacker ethos of taking parts that are built for something else and then applying it to some new context,” co-lead investigator Matthew Isaacson, a post-doctoral researcher at Cornell University, said in a news release from the college. The perfect size display, as it turns out, for a mouse VR headset is pretty much already made for smart watches. We were lucky that we didn’t need to build or design anything from scratch. We could easily source all the inexpensive parts we needed.”

Mice are frequently used in studies of brain activity, because of their similarity to aspects of the human brain. Including vision and learning. For years, brain researchers have used large projector screen as a way to create simple virtual reality environments. But these devices frequently generated so much light and noise that they overwhelmed the VR effect.

“The more immersive we can make that behavioral task, the more naturalistic of a brain function we’re going to be studying,” senior researcher Chris Schaffer, a professor of biomedical engineering at Cornell, said in a news release.

The new VR design, called MouseGoggles, includes a mouse standing on a treadmill shaped like a ball. The headset is attached to its head and held in place with a rod while the mouse runs around on the treadmill.

To see if the headset worked, researchers projected an image of a dark blob that they wanted to look like it was approaching the mice. “When we tried this kind of a test in the typical VR setup with big screens, the mice did not react at all,” Isaacson said. “But almost every single mouse, the first time they see it with the goggles, they jump. They have a huge startle reaction. They really did seem to think they were getting attacked.”

The researchers also examined key brain regions for vision, to make sure the VR images were working like real images. Results from the visual cortex confirmed that the goggles form clear, high-contrast images that mice can see, and readings from the hippocampus confirmed that mice are reacting to the virtual environment provided them.

These mouse VR goggles could be used to help study brain activity that occurs as creatures move around in an environment, giving researchers insights into normal and abnormal brain function. VR is also being used to help people rehab from nerve and brain injuries, as well as provide insights into conditions like ADD or dementia, and how our brains change in a VR environment.

VR can be a powerful experience! Some people have a sense of vertigo when experiencing VR, this research could hep understand how to prevent that side-effect.

How It Works

At a high level, the setup is basically tiny “VR goggles” for mice, built around small circular screens (the kind you might find in a smartwatch) and driven by a Raspberry Pi. Here’s the gist of how it works:

1. Small Circular Displays:
   • The displays are the same size and shape as those used in wristwatches. They’re compact, circular LCD or OLED panels with a few centimeters of diameter.
   • By using these mini screens, researchers can position them very close to a mouse’s eyes, mimicking the way our own VR headsets use small screens to cover our entire field of view.
2. Fresnel Lenses and Enclosure:
   • Each display is paired with a Fresnel lens—think of it as a thin, lightweight magnifying lens. This helps bring the screen’s image into focus at the short range a mouse needs, and also stretches the image to fill more of the mouse’s view.
   • These components (the screen and lens) are mounted in a 3D-printed shell or “enclosure” that fits around the mouse’s head.
3. Field of View for Mice:
   • Mice obviously have different visual needs than humans. Their depth of field and the way they see at wide angles are not the same as ours.
   • The design angles the displays so that each one covers a wide portion of the left or right eye’s field. Combined, the two screens give binocular coverage.
4. The Raspberry Pi and Game Engine:
   • A Raspberry Pi 4 runs the show. It generates the visuals (for instance, using the Godot game engine) and sends separate left-eye and right-eye images out to the two watch-sized displays.
   • Because the Pi can run a 3D environment, it can adjust the perspective for each eye, giving a form of stereo vision—enough that mice can perceive a simulated 3D scene or at least be immersed in a 360° visual environment.
5. Sensors and Interactivity:
   • The Pi also receives signals from other devices, like a treadmill (so if the mouse walks, the scene can move accordingly) and a lick sensor (to measure when the mouse interacts in certain ways).
   • Those same signals can trigger “rewards” (like a drop of water) or record behavioral data during experiments.

By presenting virtual scenes to the mouse in a highly controlled way, scientists can study how the mouse’s brain processes visual cues, navigates, or learns tasks, without the confounding variables you get in a real world environment.

In plain English, they’ve effectively cobbled together a mini VR headset from off-the-shelf smartwatch displays, a couple of plastic lenses, and a standard hobbyist microcomputer (the Raspberry Pi). It’s a compact, custom solution that lets mice “see” a virtual world, just like humans see through VR goggles, but scaled down to mouse-size and tailored to how rodents actually focus on and perceive visual information.

For more information about the project, including the in-depth neurological analysis and maths behind it, read the full report as published in Nature Methods.