When Eugene Aserinsky and Nathaniel Kleitman of the University of Chicago discovered rapid eye movement (REM) sleep in the 1950s, The answers to these questions seem to be within reach. At that time, two scientists recorded brain activity by placing electrodes on the scalp, near the eyeballs and muscles (that is, through EEG, EOG and EMG ), and they observed a special sleep stage for the first time. At this stage, the brain neurons are very active, very similar to the waking state, so this kind of sleep is also called " paradoxical sleep ".
In addition, they observed that while the brain is highly active, the eyeballs will continue to move quickly. Based on this characteristic, they decided to use the acronym REM, which stands for "rapid eye movement," to refer to this stage of sleep.
These findings aroused the curiosity of the two scientists. They woke up the volunteers who were in the REM sleep stage of the experiment and asked them if they had dreams before waking up. The results showed that 74% of the volunteers remembered that they had a dream. In other sleep stages (also known as non-rapid eye movement sleep, or NREM sleep), this proportion drops to 17%. Therefore, it is not difficult for us to understand why when researchers initially published these results, they claimed that they found "a way to determine whether dreams will occur and how often they occur."
In a recent experiment, we wanted to find out whether it is possible to predict the dreams of volunteers in real time. When monitoring volunteers’ activities in the posterior cortical hot zone, as long as the proportion of high and low frequency activities in the NREM sleep phase exceeds a certain value,We will wake them up. If high-frequency activity far exceeds low-frequency activity, we would guess that the volunteer is dreaming. In this way, we can achieve 87% accuracy when predicting whether the volunteer is dreaming or not.
But it also raises other questions: Will the posterior cortical hot zone help us predict one day whether a person is conscious during sleep or other non-awake states (such as coma or general anesthesia)? How is the posterior cortical hot zone activated? How are the images that appear in the dreams determined, and what are their functions? Is it possible for us to predict most of the content of the dream, or even the entire dream?
There have been scientific experiments trying to answer these questions. A study published in Science by Yukiyasu Kamitani of the Nara Institute of Science and Technology in Japan in 2013 showed that maybe we will be able to view the content of dreams in real time soon. By activating the visual area (including the posterior cortical hot zone) and using machine learning technology, Kamiya's research team successfully deciphered their dreams using magnetic resonance imaging (MRI) after the volunteers fell asleep, and reconstructed them in the form of video.
One of the videos showed a series of images related to letters, numbers, and calligraphy. Then the volunteer explained his dream: "I remember seeing some words. There was something similar to letter paper in the dream. Write on it. I read the words on the letter paper, it was black and white, and there was nothing around except this letter paper. Before that, I also watched a movie in which there was a person in the movie, but I can’t remember.” This example shows that based on the development of artificial intelligence, we may be able to predict the general content of the dream after falling asleep.
With the advancement of data analysis technology, perhaps in the near future, we can more easily obtain similar video materials in different sleep stages or even in waking states. Such progress can not only satisfy our curiosity to interpret dreams and thoughts,And it has more important clinical significance: For example, visualizing what is happening in the brain of a patient who has experienced brain trauma and is unable to respond to stimuli may help doctors to determine whether the patient is conscious or in a coma, so as to make more changes. Good treatment plan.
These data also help us understand how the brain generates its own real world: What is the difference between the reality (such as a dream) in the mind compared with the external real world in a waking state? What happens when the reality in the mind conflicts with the external world we perceive (such as a psychopath with hallucination )? Perhaps scientific research related to dreams can provide a new starting point, although the current findings are still insufficient to answer such questions.
The article is excerpted from "Global Science"
