What mice in VR goggles can tell us about our brains

• Researchers from Northwestern University made virtual reality goggles for lab mice to wear.
• The mice are being studied to identify the neurons in the brain that form memories.

Lab mice strapped in to mini virtual reality goggles are roaming through digital mazes in the latest breakthrough in neurobiology.

And they have a lot to teach us about how memory works, according to researchers at Northwestern University.

In pursuit of identifying the neurons in the brain that form memories, a team of researchers led by Daniel Dombeck, a professor in the university's department of neurobiology, created miniature VR goggles to place on lab mice to study how they remember navigational cues when traversing digital mazes.

"The most advanced instruments to image brain activity are large, table-top devices that cannot be carried around on a mouse's head as they move through the environment. So instead, we hold the mouse's head still under the large microscopes (so we can study their brains), and we let them run on a treadmill mounted under their limbs," Dombeck told Business Insider.

He added that the movements of the treadmill move the animal through a virtual world displayed in the goggles, complete with twisting mazes and depictions of predators like owls.

"With this set-up, we can then use our cutting-edge microscope systems to study brain activity during navigation," Dombeck said. "We are trying to identify the exact neurons in the brain that are forming memories of the mazes, and in those neurons, we are trying to identify which synapses are being modified to form the memories and through what mechanisms those synapses are modified."

Mouse research with human applications

Answering these questions with mouse brains will eventually help researchers understand how human brains know where we are in the world around us, how we form memories of our experiences and imagine solutions to our problems, and, ultimately, how our memories degrade due to neurodegenerative diseases.

The virtual environments enable researchers to use the most advanced recording instruments to study these questions. Future studies will include even smaller goggles so that mice can carry them around and run through virtual mazes in the real world.

In the earliest studies, researchers showed the mice simple mazes depicted as long hallways with a reward hidden along the way. In a few cases, they added a looming stimulation like a predator hunting the mice from the virtual "sky" above.

"This stimulation in real environments causes mice to freeze or flee, reactions they have to survive a predatory bird attack in the wild," Dombeck said. "Mice reacted the same way in our VR goggle system as mice do in real environments."

In studying how the navigation systems in the brain reacted to a looming stimulus, the neurobiologists found that, when the mice were freezing in place after seeing the virtual predator, the navigation neurons were reading out a different location from where the mice actually were.

"It was as if they were thinking about where they would rather be — a safe covered location up ahead — instead of where they were freezing," Dombeck told Business Insider. "We're excited about these results and will follow up more on this since they might help explain how imagination emerges in the brain."