Evidence of Learning and Memory in Human Brain During Sleep Observed for the First Time

Sleep is a routine that many species do. Sleeping gives many benefits to the systems of the body. In humans, some studies confirm how sleeping helps us to recover from stress and regroup our thoughts for the next day. But despite the numerous scientific research that tackles why we sleep, some aspects remain unsolved.

In a new study, sleep was discovered to have links with how we learn and exercise our memories. Specialists led the investigation from the Massachusetts General Hospital (MGH), Brown University, and the Department of Veterans Affairs.

The experts believe that the findings collected from this analysis would contribute to the development of assistive tools for individuals diagnosed with brain problems such as neurologic diseases and even injuries to the organ.

Replay Activities in Brain During Sleep

MGH Center for Neurotechnology and Neurorecovery specialist Daniel Rubin, who served as lead author of the study, explained in the institute's press release that previous analyses of the brain of animals established the occurrence of a phenomenon called 'replay' when a body is asleep.

This activity is theorized as a method for the brain to remember a new information set. For example, when a mouse is trained to pass across a maze, certain neurons fire up, and when they sleep, these exact brain cells also activate in the same order, Rubin continued.

According to Technology Networks, this replay activity is also suspected as the main reason for how we process and consolidate new information and convert short-term memories to long-term memories.

Replay, however, was only observed in animal subjects. In the latest analysis, the authors checked if seeing the process is possible in humans. According to the team, understanding how the replay works in the human brain could give us details to improve the tools and construct new therapeutic approaches that could aid people with neurological problems.

First-Ever Evidence of How Replay Happens in Motor Cortex

The experiment involved a 36-year-old male participant diagnosed with tetraplegia (quadriplegia). This illness prevents the patient from moving his upper and lower limbs due to an injury to the spinal cord. The same individual is under a BrainGate-led clinical trial of a brain-computer system that lets him use a device despite his case.

The patient was asked to play a computer game while his neuronal firings on his motor cortex were monitored through sensor implants. When the patient slept that night, Rubin's team saw that the neurons were still firing as they did earlier. Rubin said that this made the patient look like he still plays the game overnight as he sleeps.

The analysis was the first-ever evidence of replay in the human motor cortex during sleep. The team hopes that the data they gathered would assist in a quick and efficient solution for patients to regain their control following injuries or due to illnesses.

The results were published in JNeurosci, titled "Learned Motor Patterns Are Replayed in the Human Motor Cortex during Sleep."

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