Neurophysics of the University of California at Los Angeles continue to study the work of the brain in virtual reality. Not so long ago, they found out that the neurons of the brain responsible for mapping space react to virtual reality not like real conditions. The findings of scientists can be important for people who use virtual reality for games, military simulators, commercial, scientific purposes and other purposes.
“The picture of the activity of a brain area involved in spatial orientation in the virtual world is completely different than when processing activity in the real world,” said Mayank Mehta, professor of physics, neurology and neurobiology at the University of California, lead author. “As more people use virtual reality, it’s important to understand why there is such a big difference.”
Scientists have studied the hippocampus, a brain area involved in diseases such as Alzheimer's, stroke, depression, schizophrenia, epilepsy, and PTSD. The hippocampus also plays an important role in the formation of new memories and the creation of mental maps of space. For example, when a person explores a room, the hippocampal neurons become selectively active, creating a “cognitive map” of the environment.
The mechanism by which the brain creates such cognitive maps remains a mystery, but neurologists suggest that the hippocampus calculates the distance between the subject and the surrounding landmarks, such as buildings and mountains. Other signals like smells and sounds can also help the brain determine distances to objects.
To test whether the hippocampus could actually form a spatial map only by visual reference, the Meta team developed a non-invasive virtual reality environment and studied how hippocampal neurons in the rat brain reacted to the virtual world without being able to use smells and sounds as signals.
Scientists put rats on a treadmill surrounded by a “virtual world” on large video screens — such immersion was even more powerful than IMAX — and in a quiet, dark room. Then, the behavior of rats and the activity of hundreds of hippocampal neurons were measured. Also the subject of measurement was the behavior of the rats and neural activity, when they moved in a real room that looked exactly like a virtual one.
Scientists were surprised to find that the results of the virtual and real environments were completely different. In the virtual world, the rat hippocampal neurons worked quite randomly, as if they had no idea where the rats were - although the rats themselves behaved quite normally in the real and virtual worlds.
The map has completely disappeared, Meta said. - No one expected this. The activity of neurons randomly determined the position of rats in the virtual world. ”
Zahra Agadjan, a graduate student at the University of California and also the author of the work, told the following: "A thorough mathematical analysis showed that neurons in the virtual world counted the distance that the rats walked, regardless of where they were in the virtual space."
Scientists were also shocked to find that, although the rat hippocampal neurons were very active in a real environment, more than half of them turned off in a virtual environment. The virtual world used in the study was very similar to the virtual reality environment used by humans, and the neurons in the rat brain would be very difficult to distinguish from the neurons of the human brain, Meta says. “The neural model in virtual reality is significantly different from the picture of activity in the real world. We need to fully understand how virtual reality affects the brain. ”
In addition to analyzing the activity of individual neurons, the Meta team studied large groups of brain cells. Previous research has shown that a group of neurons creates a complex picture using brain rhythms.
“These complex rhythms are crucial for learning and memory, but we cannot hear or see these rhythms in our heads. They are hidden from us, says Meta. - The complex picture they create is beyond human interpretation. Neurons in this memory region communicate with each other using two completely different languages at the same time. One language is based on rhythm, the other on intensity. ”
Mehta says that every neuron in the hippocampus speaks two languages simultaneously, comparing this phenomenon with a multitude of simultaneously sounding melodies in the Bach fugue. Scientists say that in a virtual environment, the language of rhythms has a similar structure of what exists in the real world, even if it reports something fundamentally different in each of the worlds. However, language based on intensity is completely destroyed.
When people walk or try to remember something, the activity of the hippocampus becomes very rhythmic, and a complex pattern of rhythms arises, Meta says. These rhythms contribute to the formation of memories and our ability to trigger them. Meta suggests that in some people with memory disorders these rhythms are disturbed.
“The neurons involved in the memory interact with other parts of the hippocampus like an orchestra,” says Meta. “Even if every violinist and every trumpeter plays his part perfectly, they must be perfectly synchronized.”
Meta believes that rebuilding and synchronizing these rhythms, doctors will be able to restore damaged memory, but it will be very difficult. Neurons and synapses — connections between neurons — remain incredibly complex machines.
Any experiments scientists spend on rats, because in humans such research is impossible and unethical - at least for now.
The article is based on materials .
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