Press release
Wednesday, December 23, 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 epilepsy patients as they each walked through an empty room looking for a two-foot hidden spot. In an article published in Nature, scientists report that the waves flowed with a different pattern that suggests that each individual’s brain had traced the walls and other boundaries. Interestingly, each participant’s brain waves flowed similarly as they sat in the corner of the room and watched someone walk around, suggesting that these waves were also used to track other people’s movements. The study was part of the NIH brain initiative through the Advancing Innovative Neurotechnologies® (BRAIN) initiative.
“We were able to directly study for the first time how a person’s brain navigates a real physical space that is shared with others,” said Nanthia Suthana, Ph.D., adjunct professor of neurosurgery and psychiatry at David Geffen School. of Medicine at the University of California, Los Angeles (UCLA) and lead author. “Our results suggest that our brains can use a common code to know where we are and others in social environments.”
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, ages 31 to 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 believed to control navigation, at least in rodents. Over the past half century, scientists, including three Nobel laureates, have discovered, experimenting after experiment, that the 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 neuronal activity in these cells, called theta rhythms, help rodents know where they are and others as they run through a maze or swim in the maze. around a shallow pool of water.
“Several indirect tests support the role of the medial temporal lobe in the way we navigate. But proving these ideas even more has been technically difficult, ”said Matthias Stangl, Ph.D., a UCLA postdoctoral scholar and lead author of the article.
This study provides the most direct evidence to date that has supported these ideas in humans and has been made possible by a special backpack that Dr. Suthana invented as part of a project of the NIH BRAIN initiative.
“Many of the most important advances in brain research have been brought about by technological advances. 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 brain and brain disorders, ”said John Ngai, Ph.D., director of the NIH’s BRAIN Initiative.
In the center, the backpack contained a computer system that could be wirelessly connected to surgically implanted electrodes on a patient’s head. Recently, researchers demonstrated that the computer can simultaneously connect to several other devices, including virtual reality glasses, eye trackers, and heart, skin, and breath monitors.
“Until now, the only ways to directly study human brain activity required a subject to be still, either lying on a massive brain scanner or connected to an electrical recording device. In 2015, Dr. Suthana came up with an idea to solve this problem, so we risked making a backpack, ”said Uros Topalovic, MS, a graduate student at 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 role the medial temporal lobe plays in navigation, the researchers asked research participants to put on their backpacks and enter an empty 330-square-foot room.
Each wall was lined with a row of five colored signs numbered 1 through 5, one color per wall. Using a ceiling-mounted speaker, a computerized voice asked the patient to go to one of the signs. Once they got to the sign, the voice asked them to look for a two-foot-diameter place hidden somewhere in the room. Meanwhile, the backpack recorded the patient’s brain waves, walks around the room, and eye movements.
Initially, each person needed several minutes to find the place. During subsequent testing, time was shortened as site location memory improved.
Electrical recordings revealed a different pattern in brain activity. Theta rhythms flowed more strongly (with higher peaks and lower valleys) as participants approached a wall than when they walked in the middle of the room. This happened exclusively when they were looking for the place. In contrast, the researchers saw no correlation between the strength of the theta rhythm and the location when participants followed the directions to walk up 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 the boundaries are. In this case it is when we are focused and looking for something,” Dr. Stangl said.
An additional analysis supported this conclusion and helped rule out the possibility that the results were caused by other factors, such as activity associated with different movements of the eyes, body, or head.
Interestingly, they saw similar results when participants saw someone searching for a place. In these experiments, participants sat in a chair in the corner of the room with their backpacks on and their hands resting near a keyboard. Patients knew the location of the hidden location and pressed a button on the keyboard each time the other person arrived.
Again, the participant’s brain waves flowed more strongly as the other person approached a wall or place and this pattern only appeared when the person was on the hunt instead of following specific directions.
“Our results support the idea that our brains can use these wave patterns to put us in someone else’s skin,” Dr. Suthana said. “The results open the door for us to help us understand how our brain controls navigation and possibly other social interactions.”
The team of Dr. Suthana plans to explore these ideas in more depth. In addition, 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 have received NIH funding in support of 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. · The spinal cord to recover movements by updating computer programs that drive the stimulation devices.
These studies were supported by the NIH (NS103802), the McKnight Foundation (Award for Technological Innovations in Neurosciences) and the Keck Junior Faculty Award.
The NIH BRAIN initiative® is managed by 10 institutes the current research missions and portfolios complement the objectives of the BRAIN Initiative: National Center for Complementary and Integrative Health, National Eye Institute, National Institute on Aging, National Institute for 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 on Mental Health, and National Institute on Neurological and Acute Disorders.
NINDS is the leading national funder of research on the brain and nervous system. The mission of NINDS is to seek fundamental knowledge about the brain and nervous system and use that knowledge to reduce the burden of neurological diseases.
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