UCLA
neurophysicists have found that space-mapping neurons in the brain react
differently to virtual reality than they do to real-world environments. Their
findings could be significant for people who use virtual reality for gaming,
military, commercial, scientific or other purposes. 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. Since so many
people are using virtual reality, it is important to understand why there are
such big differences. The scientists were studying the hippocampus, a region of
the brain involved in diseases such as Alzheimer's, stroke, depression,
schizophrenia, epilepsy and post-traumatic stress disorder. The hippocampus
also plays an important role in forming new memories and creating mental maps
of space. For example, when a person explores a room, hippocampal neurons
become selectively active, providing a cognitive map of the environment. The
mechanisms by which the brain makes those cognitive maps remains a mystery, but
neuroscientists have surmised that the hippocampus computes distances between
the subject and surrounding landmarks, such as buildings and mountains. But in
a real maze, other cues, such as smells and sounds, can also help the brain
determine spaces and distances
To test whether
the hippocampus could actually form spatial maps using only visual landmarks, researchers
devised a non-invasive virtual reality environment and studied how the
hippocampal neurons in the brains of rats reacted in the virtual world without
the ability to use smells and sounds as cues. They placed a small harness
around rats and put them on a treadmill surrounded by a virtual world on large
video screens in an otherwise dark, quiet room. The scientists measured the
rats' behavior and the activity of hundreds of neurons in their hippocampi.
They also measured the rats' behavior and neural activity when they walked in a
real room designed to look exactly like the virtual reality room. The scientists
were surprised to find that the results from the virtual and real environments
were entirely different. In the virtual world, the rats' hippocampal neurons
seemed to fire completely randomly, as if the neurons had no idea where the rat
was -- even though the rats seemed to behave perfectly normally in the real and
virtual worlds. Mathematical analysis showed that neurons in the virtual world
were calculating the amount of distance the rat had walked, regardless of where
he was in the virtual space. They also found that although the rats'
hippocampal neurons were highly active in the real-world environment, more than
half of those neurons shut down in the virtual space.
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