Facts About How the Brain Maps to Where we and Others Move Revealed
Research shows that our brains know where we and others are in social settings
First of all, scientists recorded how our brains orient themselves in physical space and monitor the location of other people.
The researchers used a special backpack to wirelessly monitor the brain waves of epileptic patients as they each walked through an empty room looking for a hidden spot two feet away.
In an article published in Nature, scientists report that the waves flow in different patterns, indicating that everyone’s brain has drawn walls and other boundaries.
Interestingly, the brain waves of all the participants flowed the same way when they sat in a corner of the room and watched another person walk, suggesting that these waves were also used to track the movements of others.
“For the first time, we can directly examine how a person’s brain regulates itself in real physical space shared with others,” said Nanthia Suthana, assistant professor of neurosurgery and psychiatry at the David Geffen School of Medicine at the University of California. in Los Angeles (UCLA). and senior writer. “Our results show that our brains can use common codes to tell where we and others are in the social environment.”
Dr. The Suthana’s Laboratory studies how the brain controls learning and memory. In this study, his team worked with a group of participants with drug-resistant epilepsy, aged 31 to 52, whose brains were surgically implanted with electrodes to control their seizures.
The electrodes are located in a memory center in the brain called the medial temporal lobe, which also controls navigation, at least in rodents. Over the past half-century, scientists, including three Nobel Prize winners, have discovered – experiment after experiment – that the neurons in these lobes, known as grid cells and place cells, act as a global positioning system.
The researchers also found that low-frequency waves of neural activity from these cells called the theta rhythm helped rodents know where they and others were when walking through mazes or swimming around shallow puddles.
“Some evidence supports a role for the medial temporal lobe in navigation. However, further examination of this idea is technically difficult,” said Matthias Stangl of UCLA and the lead author of the article.
This study provides the most direct evidence to date for these ideas in humans and is made possible by the special backpack that Dr. Suthana as part of the NIH BRAIN Initiative project.
The backpack contains a computer system that can be connected wirelessly to electrodes that have been surgically implanted in the patient’s head. Researchers recently demonstrated that computers can be connected to several other devices simultaneously, including virtual reality glasses, eye tracking, and heart, skin, and breath monitors.
“Until now, the only way to directly examine activity was to have an object that was not moving, lying on a large brain scanner, or connected to an electric recorder. In 2015, Dr. Suthana came to me with the idea of a solution,” To having us risk making a backpack, “said Uros Topalovic, author of the study.” The backpack frees the patient and allows us to learn how the brain works during natural movements. “
To investigate the role of the medial temporal lobe in navigation, the researchers asked study participants to wear backpacks and enter a space of 330 square meters.
Each wall is lined with a series of five colored marks numbered 1 to 5, one color per wall. A computer sound through a loudspeaker mounted on the ceiling prompts the patient to go to one of the signs. When they reached the nameplate, the voice asked them to look for a two-foot diameter spot hidden somewhere in the room. Meanwhile, the backpack records the patient’s brain waves, pathways through space, and eye movements.
Initially, it took everyone a few minutes to find the place. During the following tests, the time decreased as the location memory was increased.
The electrical records show clear patterns of brain activity. The theta rhythm flows louder – with higher peaks and lower valleys – as participants approach the walls than when roaming in the center of the room. This only happened when they were looking for the place. Conversely, when participants followed directions to go to the colored markings on the wall, the researchers saw no relationship between rhythmic strength and theta position.
“These results support the idea that theta rhythms in certain mental states can help the brain recognize boundaries. In this case, we are focused and looking for something,” said Dr. Stangl.
The further analysis supported this conclusion and helped rule out the possibility that the results were caused by other factors, such as activities involving different eye, body, or head movements.
Surprisingly, they saw similar results when the participants saw other people looking for a place. In this experiment, participants sat in a chair in the corner of the room with their backpacks and hands placed near the keyboard. The patients knew the location of the hidden spot and pressed a key on the keyboard every time another came.
Again, the participants’ brain waves flow the most when the other person approaches a wall or dot, and this pattern occurs only when the person is hunting rather than following specific instructions.
“Our results support the idea that our brains can use these wave patterns to accommodate other people’s homes,” said Dr. Suthana. “The results open the door for us to understand how our brains control navigation and possibly other social interactions.”