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To reach that conclusion, a team from the University of Michigan and Rice University analyzed rats’ brain-wave patterns during wakefulness and sleep.
Neurons in the brain’s memory center during sleep do more than replay past experiences. New findings suggest they also peek into the future, rehearsing actions that haven’t happened yet.
How the Research Was Conducted
The researchers recorded rats’ brain-wave activity while the animals were awake and asleep. They collected data before, during, and after the rodents solved tasks in a maze to see how neural activity during rest might benefit later performance.
“We tackled this problem by linking the activity of each individual neuron to the activity of other neurons,” said anesthesiologist Kamran Diba, a co-author of the study. He noted that the ability to “track the contribution of neurons even without external stimuli was a significant breakthrough.”
The novelty of the approach lay in the team’s ability not only to connect physical locations in the maze with specific neural activity in real time, but also to work in reverse—correlating neural activity with points in the maze while the rats were sleeping.
This was made possible through a machine-learning process that weighs the relationships between neurons rather than viewing them in isolation. Based on how the rats’ neurons fired during sleep and then during their later attempts to navigate the maze, the rodents weren’t merely dreaming about places they’d already visited; they were also rehearsing potential new routes.
The results shed light on how activity in certain neurons maps onto specific locations. That mapping is dynamic, and it appears to involve the sleeping brain, as reported by Science Alert.
When the rats were returned to the maze after waking, the neural activity measured during sleep partly predicted new ways they explored their environment. The matches weren’t exact, but they were close enough to suggest a link between dreaming and future intentions.
“When we return the animals to the environment a second time, we can confirm that these changes truly reflect what they learned while they were sleeping,” noted neurobiologist Caleb Kemere.
Sleep is known to help form memories. And while this study involved rats, it’s likely something similar happens in the human brain: a kind of rehearsal for future actions.
“It’s not necessarily the case that during sleep neurons are only stabilizing memories of experiences. It turns out that some of them are doing something else,” Kemere said.
The study’s findings were published in the journal Nature.
