Although it may be hard to believe, scientists have been using virtual reality setups to study brain activity in laboratory mice for many years. These systems used to be made by surrounding mice with flat screens. Of course, such methods had obvious limitations in simulating a realistic environment.
Now, a team at Northwestern University has developed tiny VR glasses that cover a mouse’s face and even most of its body to create a more immersive experience. This allowed them to simulate overhead threats for the first time and map the mice’s brain activity in the process.
The system, called Miniature Rodent Stereo Lighting VR (or iMRSIV), is not attached to the mouse’s head like VR headsets produced for humans. Instead, the glasses are placed at the front of the treadmill and surround the entire field of view as the mouse runs in place. “We designed and manufactured a special holder for the glasses,” says John Issa, one of the lead authors of the study. “The entire optical display (screens and lenses) goes around the mouse.”
Researchers say that in their tests, mice adapted to the new VR environment faster than previous setups. To recreate the presence of overhead threats, such as birds swooping in for food, the team envisioned expanding dark spots at the tops of the screens. The way they respond to threats like this “is not a learned behavior, it’s an imprinted behavior,” says lead author Dom Pinke. “It’s hardwired into the mouse’s brain.”
Thanks to this method, the researchers were able to record both the mice’s outward physical responses, such as freezing or speeding up, and their neural activities. In the future, they could flip the script and let the mice act as hunters to see what happens when they hunt insects.
An article on the method was published in the journal Neuron.
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