News release
Wednesday December 23, 2020
Scientists first recorded how our brains navigate physical space and keep track of the location of others. Researchers used a special backpack to wirelessly track the brain waves of epilepsy patients as they all walked through an empty room in search of a hidden two-foot spot. In an article published in Nature, the scientists report that the waves flowed in a distinct pattern, suggesting that each individual’s brain mapped the walls and other boundaries. Interestingly, each participant’s brainwaves flowed in a similar way when they sat in the corner of the room and saw someone else walking around, suggesting that these waves were also used to track other people’s movements. The study was part of the NIH’s Brain Research through Advancing Innovative Neurotechnologies® (BRAIN) Initiative.
“We were able for the first time to directly study how a person’s brain navigates a physical space that is shared with others,” said Nanthia Suthana, Ph.D., an assistant professor of neurosurgery and psychiatry at the David Geffen School of Psychiatry. Medicine. from the University of California, Los Angeles (UCLA) and senior author. “Our results suggest that our brains may use a common code to know where we and others are in social situations.”
Dr. Suthana’s lab studies how the brain learns and controls memory. In this study, her team worked with a group of participants with drug-resistant epilepsy, aged 31-52, whose brains have been surgically implanted with electrodes to control their seizures.
The electrodes reside in a memory center in the brain called the medial temporal lobe, which is also thought to control navigation, at least in rodents. Over the past half-century, scientists, including three Nobel laureates, have discovered experiment after experiment that neurons in this lobe, known as grid cells and place cells, act as a global positioning system. In addition, the scientists found that low-frequency waves of neural activity through these cells called theta rhythms help rodents know where they and others are as they run through a maze or swim around a shallow pool of water.
“Several pieces of indirect evidence support the role of the medial temporal lobe in our navigation. But further testing these ideas has been technically difficult, ”said Matthias Stangl, Ph.D., a postdoctoral researcher at UCLA and the lead author of the paper.
This study provides the most direct evidence to date supporting these ideas in humans, and it was made possible by a special backpack that Dr. Suthana’s team invented as part of a NIH BRAIN Initiative project.
“Many of the most important breakthroughs in brain research have been brought about by advances in technology. This is what the NIH BRAIN Initiative is all about. It challenges researchers to create new tools and then use those tools to revolutionize our understanding of the brain and brain disease, ”said John Ngai, Ph.D., director of the NIH’s BRAIN Initiative .
At its core, the backpack contained a computer system that can wirelessly connect to electrodes surgically implanted in a patient’s head. Recently, the researchers showed that the computer can be connected to several other devices at the same time, including virtual reality glasses, eye trackers, and heart, skin and respiratory monitors.
“Until now, the only way to directly study human brain activity has been a subject who had to be still, either lying in a huge brain scanner or connected to an electrical recording device. In 2015, Dr. Suthana came to me with an idea to solve this problem and so we took the chance to make a backpack, ”said Uros Topalovic, MS, a graduate student at UCLA and an author of the study . “The backpack frees the patient and allows us to study how the brain works during natural movements.”
To investigate the role the medial temporal lobe plays in navigation, the researchers asked the study participants to put on the backpack and enter an empty space of 330 square meters.
Each wall was lined with a row of five colored boards numbered 1 through 5, one color per wall. Via a ceiling-mounted speaker, a computer-controlled voice prompted the patient to walk to one of the boards. Once they got to the sign, the voice asked them to look for a spot two feet in diameter hidden somewhere in the room. Meanwhile, the backpack recorded the patient’s brain waves, pathways across the room, and eye movements.
Initially, it took each person a few minutes to find the place. In subsequent trials, the time shortened as their memory of the location of the site improved.
The electrical recordings revealed a clear pattern in brain activity. The theta rhythms flowed more strongly – with higher peaks and lower lows – when the participants approached a wall than when they wandered into the center of the room. This only happened while looking for the place. In contrast, the researchers saw no relationship between the strength of the theta rhythm and its location when the participants followed the directions to walk to the colored signs on the wall.
“These results support the idea that under certain mental states, theta rhythms can help the brain know where boundaries lie. In this case, it’s when we’re focused and looking for something, ”said Dr. Stangl.
Further analysis supported this conclusion and helped rule out the possibility that the results were caused by other factors, such as activity related to different eye, body, or head movements.
Strangely, they saw similar results when the participants watched someone else search for a place. In these experiments, the participants sat on a chair in the corner of the room with their backpacks on and their hands at a keyboard. The patients knew the location of the hiding place and they pressed a button on the keyboard when the other person approached it.
Again, the participant’s brainwaves flowed most strongly when the other person approached a wall or spot and this pattern appeared only when the person was on the hunt rather than following specific directions.
“Our results support the idea that our brains can use these wave patterns to put us in someone else’s shoes,” said Dr. Suthana. “The results open the door to help us understand how our brains control navigation and potentially other social interactions.”
Dr. Suthana’s team plans to explore these ideas more deeply. In addition, the team has made the backpack available to other researchers who want to know more about the brain and brain disorders.
This year, more than 175 research groups have received funding from the NIH to support a wide variety of projects, ranging from mapping the neural circuits that determine what an octopus sees to helping people paralyzed by spinal cord injuries manage their movements. recover it by upgrading computer programs that include neural stimulation devices.
These studies were supported by the NIH (NS103802), the McKnight Foundation (Technological Innovations Award in Neuroscience), and the Keck Junior Faculty Award.
The NIH BRAIN Initiative® is operated by 10 institutes whose missions and current research portfolios complement the goals of the BRAIN initiative: National Center for Complementary and Integrative Health, National Eye Institute, National Institute on Aging, National Institute on Alcohol Abuse and Alcoholism, National Institute of Biomedical Imaging and Bioengineering, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute on Drug Abuse, National Institute on Deafness and other Communication Disorders, National Institute of Mental Health and National Institute of Neurological Disorders and Stroke.
NINDS is the country’s main funder of brain and nervous system research. NINDS ‘mission is to seek fundamental knowledge about the brain and nervous system and use that knowledge to reduce the burden of neurological disorders.
About the National Institutes of Health (NIH):
NIH, the national medical research agency, includes 27 institutes and centers and is part of the United States Department of Health and Human Services. NIH is the premier federal agency that conducts and supports basic, clinical and translational medical research, investigating the causes, treatments, and cures for both common and rare diseases. To learn more about NIH and its programs, visit www.nih.gov.
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