Miniature VR glasses for mice could advance neuroscience research

Mice are among the most widely used animal species in neuroscience studies because they are mammals (meaning their brains are in some ways similar to the human brain) and their genetics or behaviors can be easily manipulated in experimental contexts. Although training mice to perform specific tasks is simple, it is difficult to reliably examine their brain processes when they are outside of laboratory environments, due to the inability to bring the technologies outside imaging, the risk of mice escaping and/or other complications.

A possible solution to overcome these challenges could be to use virtual reality (VR) or augmented reality (AR) technology to observe the behavior of mice and how their brains respond when they are virtually exposed to scenes or environments. specific situations. While several research teams are attempting to develop VR glasses or headsets for mice, none of the solutions developed so far cover the animals’ entire field of vision, which could lead to delayed or different responses than those seen in animals. ‘would have mice in reality. world settings.

Researchers at Northwestern University recently developed iMRSIV (VR Miniature Rodent Stereo Illumination), a new mouse VR glasses system with full field of view, their paper, published in Neuronsuggests that this system may be better suited to conducting neuroscience research, as mice appeared to respond more quickly to virtual environments presented via iMRSIV than when scenes were presented using other previously developed VR systems.

“The most advanced instruments for imaging brain activity are large tabletop devices that cannot be carried on a mouse’s head as it moves through the environment,” said Daniel Dombeck, lead author of the article, at Medical Xpress.

“Instead, we hold a mouse’s head still under the large microscopes (so we can study its brain) and let it run on a treadmill mounted beneath its limbs. The movements of the treadmill then move the animal through the virtual world displayed in VR glasses.”

The virtual reality-based experimental setup used by Dombeck and colleagues allows them to closely study mouse brain activity under sophisticated microscopes, while the animals virtually navigate virtual environments. These environments can simulate, for example, complex virtual mazes, outdoor spaces, and other scenarios that they believe will elicit specific behavioral responses.

“We’re trying to identify the exact neurons in the brain that form maze memories, and within those neurons we’re trying to identify which synapses are changed to form the memories and by what mechanisms those synapses are changed,” Dombeck explained. . “Answering these questions will help us understand how our brains know where we are in the world around us, how we form memories of these experiences, and ultimately how these memories are degraded in neurodegenerative diseases.”

Essentially, the use of virtual environments allows neuroscientists to answer important questions about what is happening in the mouse brain in specific scenarios with unprecedented levels of precision (i.e. using the most advanced microscopes available). To carry out these experiments involving mice, Dombeck and his colleagues had until now used VR systems based on large screens, developed more than a decade ago, but these systems have significant limitations.

“With large screens, mice can still see the lab setting (table, poles, screen stands, etc.) in addition to what we are projecting on the screens,” Dombeck said. “This creates a conflict between the moving scene as the mice move around the virtual world and a static scene of the laboratory setting, which we believe reduces their immersion in the virtual world. Additionally, there is no no depth (3D) information provided by large On screens, mice see the same flat scene as we do when we watch television.

The miniature VR glasses created by this team of researchers overcome the limitations of existing large-screen VR systems for mice. First, they completely cover the mouse’s field of vision, preventing it from seeing the laboratory environments and other objects there. In addition, they allow researchers to produce a so-called stereo view, separately controlling what the mice will see in each of their eyes.

“Our eyewear design meets these criteria in large part due to a unique (custom) lens that we designed and built specifically for our eyewear,” Dombeck said. “We also used a small, flexible OLED display (like those in Apple Watches) to create a curved display surface, which also proved important for generating a wide field of view for each mouse eye.”

Dombeck and his colleagues have so far used their iMRSIV goggle system in a series of initial experiments, in which mice were presented with simple mazes consisting of long corridors in which a reward was hidden. In a few trials, they also added a “looming” simulation, with a moving object coming from the “sky” above them.

“This stimulation in real-world environments causes mice to freeze or flee, reactions they must undergo to survive an attack by predatory birds in the wild,” Dombeck said. “Notably, mice reacted the same way in our VR glasses system as they did in real environments. With this behavior in VR, we could then carry out the first studies of how navigation systems in the brain respond to a such imminent stimulus (using the advanced brain imaging systems mentioned above).

Overall, the initial results collected by the researchers suggest that their iMRSIV system is much more effective than VR systems previously developed for mice, as it elicits faster behavioral responses in mice. In the “imminent object coming from the sky” scenario, they also revealed an interesting pattern in some mice.

“We found some very interesting results in a few mice,” Dombeck explained. “Specifically, when these mice froze in place after the loom, the navigation neurons read a different location than where the mice actually were. It was as if these mice were thinking about where they would prefer to be ( (e.g., a covered safe). location forward), instead of where they were frozen. We are excited about these results and will follow this further as they could help explain how imagination emerges in the brain .

The new VR glasses system created by Dombeck and colleagues could soon be further improved and used by other neuroscientists. In the future, this could pave the way for interesting new discoveries about what happens in the brains of mice, and potentially other mammals, when they are in different scenarios or when they engage in particular behaviors.

“In our next studies, we also want to make the glasses smaller, so that mice can also carry them and navigate virtual mazes in the real world,” Dombeck added.

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