Space-Mapping Neurons React Differently To Virtual Reality

Chuck Bednar for – Your Universe Online
While virtual reality technology can recreate sensory experiences like sight, sound and touch, a new study from UCLA neurophysicists has found that the space-mapping neurons located in the brain’s hippocampus aren’t necessarily fooled – they react differently to the simulations than they do to real-world environments.
The hippocampus is the region of the brain involved in conditions such as Alzheimer’s disease, depression, epilepsy, post-traumatic stress disorder (PTSD), stroke and schizophrenia, the researchers explained, and it also plays an important role in forming new memories and creating “cognitive maps” as a person explores a new environment.
The mechanisms used to develop those mental maps remain a mystery, but neuroscientists have determined that the hippocampus is able to compute distances between the subject and his or her surrounding landmarks. In an actual maze, however, cues such as smells and sounds can also help the brain determine distances and spaces.
Image Left: UCLA’s Mayank Mehta. Credit: Reed Hutchinson/UCLA
“The pattern of activity in a brain region involved in spatial learning in the virtual world is completely different than when it processes activity in the real world,” senior author Mayank Mehta, a UCLA professor of physics, neurology and neurobiology in the UCLA College, said in a statement. “Since so many people are using virtual reality, it is important to understand why there are such big differences.”
In research published Wednesday in the journal Nature Neuroscience, Mehta’s team tested to see if the hippocampus could form spatial maps using only visual landmarks. They devised a noninvasive virtual reality environment, then studied how the hippocampal neurons in the brains of rats reacted without being able to rely on sounds and smells.
Each rat was outfitted with a small harness and placed on a treadmill surrounded by large video screens depicting a virtual environment described by the study authors as more immersive than IMAX. The room was otherwise dark, and the scientists measured the behavior of the rats and the activity of the neurons in their hippocampi. They then repeated those measurements when the rodents walked in a real room identical to the VR environment.
Much to their surprise, the scientists found that the results from both the virtual and real-world environments were completely different. While in the VR world, the rats’ hippocampal neurons appeared to fire randomly, suggesting that the neurons had no idea where the rat was. Despite the fact that the rodent appeared to behave perfectly normally in both the real and virtual environments, their spatial map appeared to completely disappear.
“Nobody expected this. The neuron activity was a random function of the rat’s position in the virtual world,” Mehta, director of a W.M. Keck Foundation Neurophysics Center and a member of UCLA’s Brain Research Institute, told UCLS’s Stuart Wolpert. He added that “the neural pattern in virtual reality is substantially different from the activity pattern in the real world. We need to fully understand how virtual reality affects the brain.”
By retuning and synchronizing these rhythms, Mehta believes that doctors could be able to repair damaged memory. However, this would still be an “enormous” challenge, as neurons and the connections between them (synapses) combine to form an immensely complex network. He had previously demonstrated in previous research that the hippocampal circuit rapidly evolves with learning, and that brain rhythms play a critical role in this process.
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