When a person sits quietly, suddenly their brain becomes "distracted", as if it has turned to a completely different world, possibly recent experiences or past memories. In fact, it may have been just a daydream. So, what happens in the brain while daydreaming? This is a question that neuroscientists find difficult to answer. According to a study published in the journal Nature on the 13th, the research team led by Harvard Medical School in the United States is one step closer to solving this problem. Research also suggests that daydreaming may shape the brain's future response to what it sees. In this new study, team members repeatedly showed mice two pictures composed of different chessboard patterns, each time showing the mice one picture. They had the mouse look at a gray screen for another minute between the two images. The team simultaneously recorded the activity of approximately 7000 neurons in the visual cortex. Researchers have found that when mice look at two images, neurons discharge in completely different specific patterns. When a mouse looks at a gray screen, neurons sometimes discharge in a similar but not entirely identical pattern, just like when a mouse looks at a picture, which is a sign that it is daydreaming. These daydreams only occur when the mouse is relaxed, manifested as calm behavior and smaller pupils. The next discovery was completely unexpected. Throughout the day and even in the following days, the activity patterns of mice viewing these images changed, which neuroscientists refer to as "representation drift". However, this drift is not random. Over time, the patterns associated with the image become more distinct, and ultimately each image involves an almost completely independent set of neurons. Finally, researchers found that daydreaming behavior in the visual cortex occurs simultaneously with replay activity in the hippocampus, indicating that the two brain regions communicate during daydreaming. The research findings provide an interesting clue that daydreaming may play a role in brain plasticity when in a quiet and awake state, indicating that the brain has the ability to self reshape new experiences. (Reporter Zhang Jiaxin) (Liaoxin News Agency)