Star Trek-style holodeck for mice reveals how brains produce mental maps

“Mental map” might sound like a GCSE revision tactic (more on that later in the week), but it actually refers to the way in which animals and people conduct spatial cognition. Deciphering where you are in the world, how far you’ve travelled, and acclimatising to new areas are all components of spatial awareness. Carrying out a systematic study of such a complex and intuitive thought process has proved challenging, until now.

Neuroscientists have constructed a kind of holodeck able to simulate a virtual world, à la Star Trek. Dr. Andrew Straw, professor of biology at the University of Freiburg, confirmed that prior to the recent creation, the holodeck was something neuroscientists had “envied […] from the world of science fiction.” It would, he said, “enable key experiments in which we could artificially decouple an animal’s movement from its perception.”

The holodeck was put to the test with mice, fish, and flies, in a joint venture between the University of Freiburg, the University of Vienna, and the Medical University of Vienna, Austria. The animals tested perceived the holodeck-simulated objects as real, in turn changing their behaviour in different environments. This allowed neuroscientists to study their spatial cognition in a controlled, malleable environment.

Researchers wanted to decouple the action-perception cycle, in order to establish a firmer grasp on the cognitive processes that turn sensation into action. “We created an immersive, 3-D virtual reality in which the animals could move freely because we wanted our visual scenery to tie in naturally with the animal’s own action-perception cycle,” said Straw. The holodeck was used to create visual obstacles such as pillars, plants and, in keeping with the Star Trek overtones of the endeavour, a fleet of video game space invaders.

Using multiple high-speed cameras and a tracking computer program, the researchers were able to monitor the animals’ movements. Experiments were conducted to see if mice were afraid of virtual heights, to change the flight paths of flies, and to see how fish altered their behaviour in the context of a changing virtual environment.

“Scientists will now be able to run experiments in which animals receive completely naturalistic feedback from their proprioceptive and vestibular systems while showing them precisely controlled visual scenery,” said Professor Straw via email. “This would allow running experiments in which animals are “teleported” (virtually, of course) and checking whether it seems they notice that teleportation and whether they can continue to navigate after being teleported.”

He went on to explain that the research could pave the way for increased understanding about how space is represented in the brain: does the brain store something akin to a real map, or does it string together a series of individual locations? “If the animal’s navigation suffers due to teleportation,” Professor Straw concluded, “it would suggest that animals do store something like a real map.”

As well as giving researchers fresh insight into spatial cognition, the experiments proffered a historic solution to the hitherto unsolved dilemma of how to directly manipulate interaction between multiple individuals. That being said, there were plenty of schoolgirls in my day who managed it…

Images: Straw Lab