In the field of neurobiology, the pursuit of more in-depth research often requires innovative technical means. Recently, researchers at Northwestern University unveiled a remarkable result by designing a new virtual reality (VR) goggle for mice, called Miniature Rodent Stereo Illumination VR (IMRSIV).
This breakthrough technology not only provides a more immersive experience, but also allows researchers to more accurately study the neural circuitry behind behavior by simulating the natural environment more realistically. Compared to the previous advanced systems, these systems have changed the status quo of just stacking screens around mice, which can be said to be a qualitative leap.
In previous devices, mice could still see the lab environment peeking out from behind the screen, and the flatness of the screen could not convey three-dimensional depth. Another drawback was that the researchers couldn't easily mount the screen on the head of a mouse to simulate an overhead threat, such as an imminent bird of prey.
And the new VR glasses almost solve these problems. And as VR becomes more widespread, these glasses could also help researchers gain insight into how the human brain adapts and responds to repeated exposure to VR – an area that is currently poorly understood. The study was recently published in the journal Neuron. It's also the first time researchers have used a VR system to simulate a threat overhead.
Daniel Dombeck of Northwestern University, senior author of the study, said: "We have been using VR systems for guinea pigs for the past 15 years. Until now, laboratories have used large computers or projection screens to surround animals. For humans, it's like watching TV in the living room. You can still see your couch and your walls. There are hints around you that tell you that you are not in the scene. Now imagine wearing VR glasses, like the Oculus Rift, which occupies your entire field of vision. You can't see anything other than the projected scene, and each eye projects a different scene to create depth information. This has always been missing for mice. ”
Dombeck is a professor of neurobiology at Northwestern University's Weienberg School of Arts and Sciences. His lab is at the forefront of developing VR-based systems and high-resolution laser imaging systems for animal research. The results of this research undoubtedly bring new perspectives and depth to the field of neurobiology, and make people look forward to more innovations and breakthroughs in the future.
The value of virtual reality (VR).
While it is possible to observe animals in their natural environment, it can be difficult to gain real-time insight into the patterns of their brain activity when interacting with the real world. To overcome this challenge, the researchers cleverly integrated VR into the laboratory environment. In these elaborate experimental scenes, the animals will be shuttled on a treadmill through projection scenes such as virtual mazes.
By having mice run in place on a treadmill — rather than being left to run freely in their natural environment or in a physical maze — neurobiologists are able to use specialized tools to deeply observe and accurately map the mice's brain activity as they traverse virtual space. Ultimately, this will help researchers uncover general principles of how neural circuits that are activated during various behavioral processes encode information.
"VR is essentially a recreation of a real environment. While our VR system has had some success, the animals may not be as immersed as they are in the real world. It takes a lot of training to get the guinea pig to focus on the screen and ignore the distractions of the surrounding labs. ”
Launch of IMRSIV
As hardware miniaturization continued, Dombeck and his team had the idea of developing a virtual reality (VR) glasses that would more realistically replicate the real environment. Using custom-designed lenses and miniature organic light-emitting diode (OLED) displays, they were able to create a compact glasses called IMRSIV.
ImRSIV glasses are delicate and consist of two lenses and two screens – one for each head, one for each eye – to ensure stereoscopic 3D vision. This provides a wide 180-degree field of view for each eye, allowing the mouse to fully immerse itself and effectively shield the mouse from the surrounding environment.
Unlike human VR glasses, IMRSIV (pronounced "immersive") does not wrap around the head of a mouse. Instead, the glasses will be attached to the experimental setup and placed directly in front of the mice. This unique design is because when the mouse is running on the treadmill, the glasses need to always cover the mice's field of vision.
John Issa, a postdoctoral researcher in the Dombeck lab and co-first author of the study, said, "We designed and built a bracket specifically to support the glasses. The entire optical display system (screen and lens) surrounds the mouse, ensuring that its vision is always filled with the exciting virtual world. ”
Shorten your training time
By taking a closer look at the mice's brain activity, Dombeck and his team found that the bespectacled mice had brains that were very similar to those of free-roaming animals. In a side-by-side comparison, they found that mice wearing glasses were able to interact with the scene faster than mice from traditional virtual reality systems.
We used the same training paradigm as in the past, but the bespectacled mice learned Xi significantly faster," Dombeck said. "After the first training, they are already able to do the task proficiently. They know to run in ** and look for rewards in the right places. We think they may not actually need as much training because they can interact with the environment in a more natural way. ”
Simulates an overhead threat for the first time
Next, the researchers used glasses to simulate an "overhead threat" – something that was previously impossible because the hardware of existing imaging techniques was already located above the guinea pig, and there was no place to install a computer screen. However, the sky above the mice is where animals often look for important (and sometimes life-or-death information).
The top of the mice's field of vision is very sensitive and predators, such as birds, can be detected from above," said Dom Pinke, a researcher at the Dombeck lab and co-first author. "It's not a learned behavior;It's an act of imprinting. It is encoded within the brain of the mouse. ”
To create an imminent threat, the researchers projected a black expanding disc onto the top of the glasses — the top of the mice's field of vision. In experiments, once the mice noticed the disc, they either accelerated and ran or stalled. Both of these behaviors are common responses to overhead threats, and researchers are now able to record neural activity to study these responses in detail.
"In the future, we want to study how a mouse is not a predator but a predator, for example we can observe its brain activity when it chases a fly," Issa said. This activity involves a lot of depth perception and the process of estimating distances, and these are the things that we are able to begin to capture. ”
Popularize neurobiology
Neurobiology, as a science that studies the function of the nervous system and brain, has always been an important field in the scientific community. However, due to its complexity and high technical requirements, many people are unfamiliar with this field. In order to popularize neurobiology and make this field more accessible to more people, Dombeck and his team have made great efforts.
In addition to opening the door for more research, Dombeck hopes the VR glasses will also open the door to new researchers. Because these glasses are relatively inexpensive and require less lab equipment, he believes they can make neurobiological research easier.
Traditional VR systems are quite complex," says Dombeck. "They're expensive and bulky, and they often require a lab with a large footprint. Also, it takes a long time to train a mouse to complete a task, which limits the number of experiments you can perform. Although we are still working on improvements, our glasses are small, relatively inexpensive, and relatively user-friendly, so this may make VR technology more accessible to other labs. ”
With these glasses, researchers can more conveniently conduct neurobiological experiments without the need for excessive equipment and training time. This allows more researchers to have access to the field and carry out more research work.
In addition, the research of Dombeck and his team brings new perspectives and depth to the field of neurobiology. By observing the brain activity of mice, they revealed the general principles of how neural circuits encode information during various behavioral processes. This is also important for understanding how the human brain works.
Popularizing neurobiology requires not only more talent and financial investment, but also the enthusiasm and patience of scientists. The research of Dombeck and his team has breathed new life into the development of this field and opened up more possibilities for us to better understand ourselves and the world.