Is it possible to learn and remember in sleep? What happens during sleep? This issue has been debated by scientists for years, but a recent study by researchers at Massachusetts General Hospital (MGH), conducted in collaboration with experts from Brown University, the Department of Veterans Affairs, and several other institutions, gives us new clues to solving this puzzle. New research recently published in the journal Neuroscience published, it may explain how a person remembers different things in a dream or why we learn in different areas. It may also help to create assistive devices for people with neurological diseases or various injuries.
According to the main author of this research and a neurologist, Daniel RobinPh.D. of the MGH Center for Neurotechnology and Neuroregeneration, scientists have long discovered that during sleep, a phenomenon called “replay” it happens. But what is replay? Replay is a mechanism that the brain uses to remember new information. When a mouse is taught to navigate a maze, medical equipment may show that a precise pattern of brain cells, or neurons, fire when the mouse follows the correct path.
“After the mouse goes to sleep, you’ll see the neurons start firing again with the same vigor,” says Robin. Scientists theorize that the brain practices newly acquired knowledge during sleep, allowing memories to consolidate; It means that short-term memories become long-term memories.
The subject of “replay” has so far only been demonstrated in the minds of laboratory animals. Dr. Sidney S. “The unanswered question is how similar is this model to human learning,” says Cash, a neurologist, director of the Center for Neurotechnology and Neuroregeneration at MGH and one of the study’s senior authors. And can it be extended to different types of learning or learning in sleep?” He also states that understanding whether sleep replay occurs with learning new skills or not could help develop new treatments and tools for people with neurological diseases and injuries.
Robin, Cash and colleagues recruited a 36-year-old man with tetraplegia (or paralysis of four limbs) to investigate whether replay occurs in the human motor cortex (the area of the brain that controls movement). This person could not move his lower and upper limbs due to the spinal cord injury he had suffered.
In this study, the man T11 called; He is a clinical trial participant using computer intelligence that allows him to use an on-screen computer keyboard and cursor. This device by the consortiumBrainGate A collaborative effort between physicians, neuroscientists, and engineers is in progress. The aim of this institute is to create technologies to restore communication, mobility and independence to people with any neurological diseases. This consortium by Lee. R. Hockberg, PhD holder from the university Brown and administered by the Department of Veterans Affairs.
In this study, T11 were asked to perform a mental activity similar to an electronic game Simon do, where the player sees a pattern of flashing colored lights, then must remember and reproduce that sequence. All he had to do was think about moving his hand, and then the sensor in the T11 motor cortex would measure the neural data and reflect his desired hand movement; It also allowed him to move the cursor around the screen and click where he wanted. These brain signals were recorded and wirelessly transmitted to the computer.
That same night, all T11 activity in his motor cortex was recorded while he slept and then wirelessly transmitted to a computer.
“What we found was pretty incredible,” says Robin. “The subject played the exact same game in his mind while sleeping.” T11’s neural patterns during sleep exactly matched the patterns he formed in his mind during the memory matching game that same day.
“This data is the most direct evidence of re-entrainment from the motor cortex seen in humans during sleep,” says Robin. Most of the replays identified in this study occurred during slow wave sleep or deep sleep. But interestingly, when T11 was in REM sleep (the stage usually associated with dreaming), replay detection was less likely. Robin and Cash see this work as a foundation for learning more about replay in sleep and its role in learning and memory in humans.
“Our hope is that we can use this information to help create better brain-computer interfaces, and to find patterns that help people learn faster and more efficiently in situations where they’re not working,” Cash said. who have been harmed, to gain control. “This type of research is made possible because of the close interaction we have with our participants,” he adds, crediting T11 and the other participants in the BrainGate clinical trial.
Agreeing with Robin, Hackberg says, “BrainGate’s incredible participants not only provide valuable feedback on building a system to restore communication and mobility, but also enable a rare opportunity to advance neuroscience and understand how the human brain works in every different person.” . All this information will be used to build the next generation of neuroregenerative technologies.”
A little more about the expertise of the researchers of this experiment: Robin is an instructor of neurology at Harvard Medical School (HMS) Is. Cash is an associate professor of neurology at HMS. Hockberg is a senior lecturer in neurology at HMS and professor of engineering at Brown University.
This study was sponsored by the National Institute of Neurological Disorders and Stroke, American Academy of Neurology, National Institute of Mental Health, Department of Veterans Affairs, Institute MGH-Deane and funded by the Howard Hughes Medical Institute at Stanford University.