Mengchen from Ao Fei Si
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I read a few pages or words before going to bed, and when I woke up, I found that I was very impressed.
I wonder if you have had similar experiences?
Scientists have always wanted to study this phenomenon, but they have been limited by technical conditions and have been difficult to collect weak neural activity signals in the human brain at night.
With the recent development of brain-computer interface data wireless transmission technology, the opportunity has finally come.
In experiments involving volunteers, researchers have obtained direct evidence for the first time that the motor cortex of the human brain "replays" daytime activity during sleep. Daniel Rubin, first author of the
paper and Harvard Medical School , said:
Our findings are incredible. He (the volunteer) basically practiced automatically all night while sleeping.
related papers have been published in The Journal of Neuroscience, a well-known journal in the field of neuroscience .
The brain speeds up learning while you sleep
This volunteer, codenamed T11, unfortunately became a quadriplegic due to spinal cord injury .
He was implanted with the invasive brain-computer interface electrodes from the BrainGate project team, which was the same equipment used by the T5 man who participated in mind typing research last year.
In this experiment, T11 needs to play a simple video game during the day:
first observes the order in which the colored areas light up, and later controls the cursor to move in order based on memory.
This is a classic task in brain-computer interface research. The pattern of neural activity is relatively easy to capture and identify, and has appeared in related research many times before.
For ten consecutive days, T11 needs to train from 13:45 to 16:00 in the afternoon, and sleep from 23:00 to 9:00 the next morning.
During training, the brain-computer interface can decode and record the neural activity of his brain's motor cortex in real time.
T11 was not told the specific content of this experiment. He just thought that he would do recovery training as usual and fall asleep as usual at night.
But during these ten days, the researchers compared the data recorded by the brain-computer interface while he slept with the data during the day. After
used Kalman filtering and other methods to process the data, it was found that nighttime neurons replayed the training content during the day at a higher frequency interval than expected.
T11 The firing pattern of neurons during sleep is highly consistent with that during daytime training, and is even completely consistent several times.
â–³Data and visual demonstration starting at 0:50 am
This phenomenon is called offline replay (offline replay) , and has been previously verified in mice and humans while they are resting during the day.
This is the first time that replay during human sleep has been observed.
and data show that the playback speed at night is 1-4 times faster than during the day..
In other words, when you are sleeping, your brain is not only automatically learning what you learned during the day, but also accelerating learning.
And you yourself are completely unaware of all this.
The more difficult the task, the more active the brain.
A series of previous studies have also verified that the neural activity of hippocampus and neocortex during sleep of mice can practice maze running.
and similar offline replay phenomena when humans are resting during the day.
Combining these findings with experimental results, the researchers proposed the idea that
replay learning may be a retention mechanism across multiple areas of the brain, including semantic, navigation, and motor control systems. And further supports the role of sleep in memory consolidation.
In addition, this study also verified several previous important findings:
First, replay occurs mainly in the biological sense of Slow-wave sleep (Slow-wave Sleep) , which is more common The name is non-rapid eye movement stage (Non-REM Stage) , or deep sleep.
Second, replay activity was highly correlated with sharp wave ripples (Sharp Wave Ripple) caused by the hippocampus.
sharp wave ripples are rapid bursts of synchronized neuronal activity that create a high-frequency oscillation.
The relationship between â–³ replay and sharp wave ripples
Third, the more difficult the task during the day, the stronger the replay activity during sleep.
In future plans, the research team of the BrainGate Alliance plans to systematically change the difficulty of the tasks and conduct more in-depth research. The BrainGate Alliance is jointly launched by clinicians, neuroscientists, Brown University, Harvard Medical School, Massachusetts General Hospital and other institutions. The goal is to use brain-computer interface technology to help patients who have lost their limb mobility due to neurological diseases or injuries.
One More Thing
Since the brain is consolidating memory during the deep sleep stage, what is the brain doing during the rapid eye movement stage (that is, the stage where most dreams occur) ?
A previous paper in Science explained this.
During the rapid eye movement period, MCH neurons in the hippocampus that are responsible for secreting melanin accumulation hormone will help the brain actively forget unimportant information .
Dreaming mainly occurs during the rapid eye movement period, when MCH neurons are active. This is one of the reasons why the content of dreams is forgotten after waking up.
So, have you ever woken up and remembered everything you read the day before?
Paper address:
https://www.jneurosci.org/content/42/25/5007
Reference link:
[1]https://neurosciencenews.com/motor-replay-sleep-20906/
[2]https: //www.science.org/doi/10.1126/science.aba0672
[3]https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0655
[4]https://www.science.org/doi/10.1126 /science.aax9238
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