What happens when you daydream? Brain study solves the mystery
CAMBRIDGE, Mass. — Daydreaming has long been a curiosity for neuroscientists, and a recent study conducted by researchers at Harvard Medical School (HMS) is shedding new light on this widely experienced phenomenon.
The study focused on tracking the activity of neurons in the visual cortex of mice while they were in a relaxed, awake state. Surprisingly, the researchers found that these neurons occasionally fired in patterns similar to those observed when the mice were actually looking at an image. This suggests that the mice could potentially be daydreaming about the image. Interestingly, the patterns of neuron activity during these daydreams could predict how the brain would respond to the image over time.
We wanted to understand the neurobiological process behind daydreaming and its potential significance for learning and memory, says lead author of the study, Nghia Nguyen, a PhD student in neurobiology at the Blavatnik Institute at HMS.
What makes this study particularly noteworthy is that most previous research on memory formation and neuron replay has focused on the hippocampus, the brain region responsible for memory and spatial navigation. However, the HMS researchers were interested in exploring whether they could record enough neurons in the visual cortex to determine what the mouse was remembering and establish a connection to brain plasticity.
During the experiment, the researchers presented mice with two different checkerboard patterns and recorded the activity of approximately 7,000 neurons in the visual cortex. They discovered that when the mice looked at a blank gray screen between the images, their neurons fired in a manner similar to when they were actually observing the image, indicating the occurrence of daydreaming.
Interestingly, these daydreams occurred more frequently in the morning and tended to focus on the most recently seen image. Over time, the neuron activity patterns for each image became significantly different, a phenomenon referred to as representational drift. The early daydreams about an image actually helped predict how the brain’s response to that image would change.
Furthermore, it was observed that the daydreams in the visual cortex coincided with replay activity in the hippocampus, suggesting communication between these two brain regions during the process of daydreaming.
This study suggests that daydreaming may play a role in brain plasticity by helping the brain differentiate between different images or experiences. Nguyen speculates that daydreaming could be important for the brain to respond more specifically to various stimuli in the future.
When you see two different images many times, it becomes important to discriminate between them. Our findings suggest that daydreaming may guide this process by steering the neural patterns associated with the two images away from each other, explains Nguyen.
These findings align with other research indicating that quiet wakefulness following an experience can enhance learning and memory. The researchers plan to further investigate how neuron connections in the visual cortex change during the brain’s processing of an image.
Although it is yet to be determined if human daydreaming involves similar processes, preliminary evidence suggests that recalling visual imagery activates the visual cortex and hippocampus in humans as well. For now, researchers believe that allowing time for daydreaming and quiet reflection could be crucial for brain health and learning.
We feel fairly confident that if you never give yourself any awake downtime, you’re not going to have as many of these daydream events, which may be important for brain plasticity, concludes senior author of the study, Mark Andermann, a professor of medicine at Beth Israel Deaconess Medical Center and professor of neurobiology at HMS.
In conclusion, this study provides valuable insights into the neurobiological mechanisms behind daydreaming and suggests its potential significance for learning and memory. By recognizing the importance of daydreaming and allowing space for quiet reflection, individuals may be able to support their brain health and enhance their learning abilities.
Note: Researchers have yet to determine if human daydreaming involves similar processes, but the preliminary evidence is promising.
