Carlos Solis
From now on, reflections on where our dreams lead us will no longer seem so hazy. Researchers at Harvard University have found preliminary evidence that dreams play a significant role. They prepare the brain for learning and memory retention.
A team of researchers led by neurobiologist Nghia Nguyen set out to understand how dreaming works at a neurobiological level and whether these moments of quiet reflection are important for learning and memory.
Tested on Mice
It might be hard to imagine a dreamy mouse. Nevertheless, scientists have long studied the state of daydreaming in these rodents. In a recent study, the Harvard team discovered that when mice dream (or quietly reflect on what they saw earlier that day), their brains reboot in a beneficial way. Specifically, they become primed for memory and learning.
This hypothesis will need further testing. However, it is already clear that when mice are shown a black-and-white checkered pattern, they can visualize the image in their mind’s eye even after it has disappeared from view.
The study involved 13 mice, which were shown two different black-and-white images in a calm setting 64 times a day. Each image was displayed for two seconds. The experiments were repeated over several days. During this time, the team monitored the electrical activity of 7,000 neurons in the mice’s brains, including neurons from the visual cortex and the hippocampus (an area closely associated with memory consolidation).
Each of the two images ultimately triggered different patterns of neural activity in the lateral visual cortex of the mice. This part of the brain is involved in recognizing objects and their shapes.
The results showed that the mice’s brains encoded each image using different patterns of neural activity. But what is particularly interesting is that after the images were replaced with a blank computer screen, the visual cortex sometimes reactivated, producing a pattern of neural activity similar to the pattern seen when the original image was displayed.
This brief reactivation of the visual cortex was often accompanied by sharp bursts of activity in the hippocampus. This indicates that the brain effectively encoded visual information despite the absence of a stimulus.
Subsequently, the brain’s activity when viewing the image became identical to the activity during dreams about that image. This suggests that dreams strengthen some neural connections while weakening others, creating a more efficient overall response to stimuli.
What the scientists concluded
The dreaming effect, where the visual cortex is engaged in visualizing an image that is no longer present, occurred exclusively when the mice were unstimulated and calm. This was indicated, in part, by their small pupils, as reported by Science Alert.
The team says this unstimulated, dreamy state may act like sleep, consolidating memories and boosting learning.
Neurobiologist Mark Anderman, a co-author of the study, says dreams play a major role in brain plasticity. The researchers think the findings might apply to the human brain, but that will need to be confirmed in future studies.
The results of the study were published in the journal Nature.
Still, some scientists warn about potential downsides of dreaming. For instance, dreaming too much or dreaming about negative things could harm a person’s cognitive abilities, such as attention and short-term memory.
Photo: pixabay.com
