How Small VR Goggles Are Revolutionizing Brain Research with Mice

The provided image demonstrates a VR configuration, presenting an “overhead threat” in the top viewing field. Credit is attributed to Dom Pinke from Northwestern University.

Researchers from Northwestern University have created innovative virtual reality (VR) goggles specifically for mice.

In addition to being fun, these tiny goggles offer more all-encompassing experiences for mice in laboratory settings. By simulating natural environments more effectively, researchers can study the neural pathways that underpin behavior with greater precision and accuracy.

In comparison to existing high-tech systems which merely cover mice with computer or projection screens, the new goggles offer a significant upgrade. Current systems allow mice to see the lab environment beyond the screens, and the screens’ flat nature fails to project three-dimensional (3D) depth. Another issue is the difficulty in mounting screens above mice to mimic overhead threats, such as predatory birds.

The novel VR goggles bypass these problems, and as VR's popularity continues to grow, the goggles could potentially aid researchers in deriving fresh insights into how the human brain adapts to and reacts to consistent VR exposure, which is currently a sparsely researched area.

The study was published in the journal Neuron on December 8. It’s the first time a VR system has been used to mimic an overhead threat.

A glimpse through the innovative mini VR goggles. Credit is attributed to Dom Pinke from Northwestern University.

“We've been utilizing VR systems for mice for the last 15 years,” shared Daniel Dombeck, Northwestern's senior author of the study. “Until now, labs have used big computer or projection screens to surround an animal. For humans, this is comparable to watching TV in your living room. You continue to see your furniture and walls. There are cues indicating you’re not within this scene. You’ll change your perspective when you imagine wearing VR goggles, which consumes your entire field of vision. You see nothing except the scene being projected, with a different scene being projected into each eye to generate depth information. This has been lacking for mice.”

Dombeck is a neurobiology professor at Northwestern’s Weinberg College of Arts and Sciences. His lab is recognized for developing VR-based systems and highly detailed, laser-based imaging systems for animal research.

Although animal behavior can be studied in nature, capturing patterns of real-time brain activity while animals engage with the real world is extremely challenging. To tackle this hurdle, researchers have incorporated VR into lab settings. Animals navigate scenes on a treadmill, such as a virtual maze, which are projected onto surrounding screens in these experimental settings.

By keeping the mouse stationary on the treadmill, neurobiologists can use special tools to observe and map the brain as the mouse navigates virtual space. This technique greatly assists researchers in understanding the general principles of how activated neural circuits encode information during different behaviors.

“VR essentially replicates actual environments,” Dombeck stated. “This VR system has yielded substantial success, but there's a possibility that the animals might not be as engrossed as they would be in a real environment. It necessitates significant training just to get the mice to concentrate on the screens and disregard the lab surroundings.”

Due to recent advancements in hardware miniaturization, Dombeck and his team considered the possibility of creating VR goggles that more closely mimic a real environment. They created compact goggles using specially designed lenses and tiny organic light-emitting diode (OLED) displays.

Titled Miniature Rodent Stereo Illumination VR (iMRSIV), the system includes two lenses and two screens for each side of the head to independently light up each eye for 3D vision. Each eye is provided with a 180-degree viewing field that completely engrosses the mouse and blocks out the surrounding environment.

An artist’s depiction of a cartoon mouse wearing VR goggles. Credit is duly given to @rita.

Unlike human VR goggles, the iMRSIV system, pronounced “immersive,” does not encase the mouse’s head. Instead, the goggles are affixed to the experimental setup and positioned directly in front of the mouse’s face. As the mouse runs stationary on a treadmill, the goggles cover the mouse’s entire viewing field.

A custom holder for the goggles was designed and built, according to John Issa, a postdoctoral fellow in Dombeck’s laboratory and study co-first author. “The entire optical display, which includes the screens and the lenses, completely surrounds the mouse.”

By mapping the mice’s brains, Dombeck and his team found that the brains of goggle-wearing mice were activated in very similar ways as in freely moving animals. And, in side-by-side comparisons, the researchers noticed that goggle-wearing mice engaged with the scene much more quickly than mice with traditional VR systems.

“We went through the same kind of training paradigms that we have done in the past, but mice with the goggles learned more quickly,” Dombeck said. “After the first session, they could already complete the task. They knew where to run and looked to the right places for rewards. We think they actually might not need as much training because they can engage with the environment in a more natural way.”

Next, the researchers used the goggles to simulate an overhead threat — something that had been previously impossible with current systems. Because hardware for imaging technology already sits above the mouse, there is nowhere to mount a computer screen. The sky above a mouse, however, is an area where animals often look for vital — sometimes life-or-death — information.

“The top of a mouse’s field of view is very sensitive to detect predators from above, like a bird,” said co-first author Dom Pinke, a research specialist in Dombeck’s lab. “It’s not a learned behavior; it’s an imprinted behavior. It’s wired inside the mouse’s brain.”

To create a looming threat, the researchers projected a dark, expanding disk into the top of the goggles — and the top of the mice’s fields of view. In experiments, mice — upon noticing the disk — either ran faster or froze. Both behaviors are common responses to overhead threats. Researchers were able to record neural activity to study these reactions in detail.

“In the future, we’d like to look at situations where the mouse isn’t prey but is the predator,” Issa said. “We could watch brain activity while it chases a fly, for example. That activity involves a lot of depth perception and estimating distances. Those are things that we can start to capture.”

In addition to opening the door for more research, Dombeck hopes the goggles open the door to new researchers. Because the goggles are relatively inexpensive and require less intensive laboratory setups, he thinks they could make neurobiology research more accessible.

“Traditional VR systems are pretty complicated,” Dombeck said. “They’re expensive, and they’re big. They require a big lab with a lot of space. And, on top of that, if it takes a long time to train a mouse to do a task, that limits how many experiments you can do. We’re still working on improvements, but our goggles are small, relatively cheap, and pretty user-friendly as well. This could make VR technology more available to other labs.”