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Press release
Wednesday 23 December 2020
For the first time, scientists have recorded how our brains navigate physical space and track the location of others. The researchers used a special backpack to wirelessly monitor the brain waves of patients with epilepsy as everyone wandered around an empty room looking for a two-foot hidden spot. In an article published in Nature, the scientists report that the waves circulated in a separate pattern, suggesting that each individual’s brain had drawn walls and other boundaries. Interestingly, each participant’s brain waves circulated in the same way when they sat in the corner of the room and watched someone else walking around, suggesting that these waves were also used to track the movements of others. people. The study was part of NIH’s Brain Research through Advancing Innovative Neurotechnologies® (BRAIN) initiative.
“We were able to study directly for the first time how a person’s brain navigates through real physical space that is shared with others,” said Nanthia Suthana, Ph.D., assistant professor of neurosurgery and psychiatry at the David Geffen School of Medicine at the University of California, Los Angeles (UCLA) and senior author. “Our results suggest that our brains can use a common code to know where we and others are in social contexts.”
Dr. Suthana’s lab 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 reside in a memory center in the brain called the medial temporal lobe, which is also believed to control navigation, at least in rodents. Over the past half century, scientists, including three Nobel Prize winners, have discovered – experiment after experiment – that neurons in this lobe, called grid cells and place cells, act like a global positioning system. Additionally, scientists have found that low-frequency waves of neural activity from these cells, called theta rhythms, help rodents know where they and others are when they run through a maze or swim around a maze. shallow pool.
“Several pieces of indirect evidence support the role of the medial temporal lobe in the way we navigate. But testing those ideas further has been technically difficult, ”said Matthias Stangl, Ph.D., postdoctoral researcher at UCLA and lead author of the article.
This study provides the most direct evidence to date supporting these ideas in humans, and was made possible by a special backpack that Dr. Suthana’s team invented as part of an NIH BRAIN Initiative.
“Many of the most important breakthroughs in brain research have been sparked by advances in technology. This is what the NIH BRAIN Initiative is aiming for. It challenges researchers to create new tools and then use those tools to revolutionize our understanding of the brain and brain disorders, ”said John Ngai, Ph.D., director of the NIH BRAIN Initiative.
Basically, the backpack contained a computer system that can connect wirelessly to electrodes surgically implanted in a patient’s head. Recently, researchers have shown that the computer can be connected to several other devices simultaneously, including virtual reality glasses, eye trackers, and heart, skin and respiratory monitors.
“Until now, the only way to directly study human brain activity has required a subject to be stationary, lying in a huge brain scanner, or hooked up to an electrical recording device. In 2015, Dr Suthana came to me with an idea to solve this problem so we tried to make a backpack, ”said Uros Topalovic, MS, graduate student from UCLA and author of the study. “The backpack frees the patient and allows us to study the functioning of the brain during natural movements.”
To examine the medial temporal lobe’s role in navigation, the researchers asked research participants to put on the backpack and enter an empty 330-square-foot room.
Each wall was bordered by a row of five colored panels numbered 1 to 5, one color per wall. Through a loudspeaker mounted on the ceiling, a computerized voice instructed the patient to walk to one of the panels. Once they got to the panel, the voice then asked them to search for a stain one meter in diameter hidden somewhere in the room. During this time, the backpack recorded the patient’s brain waves, paths through the room, and eye movements.
Initially, each person needed several minutes to find the place. In subsequent trials, the time shortened as their memory of the spot location improved.
Electrical recordings revealed a distinct pattern of brain activity. Theta rhythms flowed louder – with higher peaks and lower valleys – when participants approached a wall than when they walked around the middle of the room. This only happened when they were looking for the place. In contrast, the researchers saw no correlation between the strength of the theta rhythm and location when participants followed the directions to walk to the colorful signs on the wall.
“These results support the idea that under certain mental states, theta rhythms can help the brain know where the limits are. In this case, it’s when we are focusing and looking for something, ”said Dr Stangl.
Further analysis supported this conclusion and ruled out the possibility that the findings were caused by other factors, such as activity associated with different eye, body, or head movements.
Oddly enough, they saw similar results when participants watched someone else look for a seat. In these experiments, participants sat in a chair in the corner of the room with their backpacks and their hands resting near a keyboard. The patients knew the location of the hidden spot, and they would press a button on the keyboard whenever the other person got there.
Again, the participant’s brain waves flowed strongest when the other person approached a wall or location and this pattern only appeared when the person was on the hunt rather than following specific instructions. .
“Our results support the idea that our brains can use these wave patterns to put themselves in another person’s shoes,” said Dr Suthana. “The results help us understand how our brains control navigation and, possibly, other social interactions.”
Dr. Suthana’s team plans to explore these ideas in more depth. Additionally, the team has made the backpack available to other researchers who want to learn more about the brain and brain disorders.
This year, more than 175 research groups received NIH funding to support a wide variety of projects ranging from mapping the neural circuits that control what an octopus sees to helping people paralyzed by spinal cord injuries to regain movement by improving computer programs that stimulate neurons. stimulation devices.
These studies were supported by the NIH (NS103802), the McKnight Foundation (Technological Innovations Award in Neuroscience) and the Keck Junior Faculty Award.
NIH BRAIN Initiative® is managed by 10 institutes whose current missions and research portfolios complement the objectives 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 of Drug Abuse, National Institute of Deafness and Other Communication Disorders, National Institute of Mental Health and National Institute of Neurological Disorders and Stroke.
NINDS is the leading funder of brain and nervous system research in the country. The mission of NINDS is to research fundamental knowledge about the brain and nervous system and to use this knowledge to reduce the burden of neurological disease.
About the National Institutes of Health (NIH):NIH, the nation’s medical research agency, comprises 27 institutes and centers and is a component of the US Department of Health and Human Services. The NIH is the principal federal agency that conducts and supports basic, clinical and translational medical research, and studies the causes, treatments, and cures for common and rare diseases. For more information about the NIH and its programs, visit www.nih.gov.
NIH… Transforming Discovery into Health®
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