Study: The brain tries to predict future experiences when sleeping

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A new study has found that the brain not only replays past events when we sleep, but also anticipates future experiences, which could lead to improved treatment for neurological disorders such as Alzheimer's.

Previous studies examined performance on memory tests after taking a nap and after periods of being awake or sleep deprived, as sleep is important for memory and learning and helps transform new experiences into stable memories.

The researchers discovered that some neurons in the brain not only replay past experiences, but also anticipate future events during sleep.

By studying hippocampal activity in mice, they found that neurons stabilize spatial representations and prepare for future tasks.

During the study published in the journal Nature, the researchers trained mice to run back and forth on an elevated track with a reward at both ends, and observed how these neurons in the hippocampus were stimulated in the process.

By examining how these neurons were stimulated on average over many round-trip cycles, the researchers estimated the spatial field of each neuron, the specific region in the environment that the neuron was “interested” in most.

They simply estimated where the rodents dreamed of being during their sleep using a statistical machine learning method.

They found that the neural activity of sleeping mice was somewhat predictive of how they would approach the maze after waking up.

The researchers observed that the spatial representations that form in the brains of mice when they encounter a new environment are mostly stable after several hours of sleep.

But the neurons also seemed to behave in a way that enabled the rodents to navigate the maze better when they were awake. This means that the rodents were not only dreaming about the places they visited in the maze, but were also working on potential new ways of behaving.

Caleb Kimmery, co-author of the study, explained: “What I loved most about this study and the reason I was so excited about it was the discovery that it is not necessary that the only thing these neurons do during sleep is consolidate the memory of the experience. It turns out that some neurons do "Ultimately something else."

He added: "We can see these other changes happening during sleep, and when we return the animals to the environment again, we can verify that these changes actually reflect something that was learned while the animals were sleeping. It is as if the second exposure to space is actually happening while the animal is sleeping." "This represents a direct observation of the neuroplasticity that occurs during sleep."