We’re constantly making memories with every experience, but how do they stick with us? It turns out that a good night’s sleep makes them last. Recent research shows that as we sleep, the neurons in our brains undergo processes that not only preserve past memories but also prepare for the creation of new memories to come.
A new study published in Nature Communications captured memory processing in mice by following neuronal activity in their brains before, during, and after learning experiences. The results suggest that proper sleep may be pivotal for learning and retaining new information.
How Are Memories Formed?
Episodic memories are primarily formed and stored in the hippocampus, located in the temporal lobe of the brain. Although the hippocampus is the main hub for memory processing, other parts of the brain are also involved. Neurons in the prefrontal cortex, which are responsible for decision-making and personality expression, play a role in recalling memories. The amygdala, on the other hand, bonds emotions to certain memories.
Memory processing takes two steps: encoding and consolidation. During the initial encoding, the brain accumulates sensory information and labels it. After this, consolidation eventually stabilizes memory traces and stores them for future recollection in the long term. Sleep helps to consolidate and strengthen memories, and it also facilitates a process called pruning, when the brain gets rid of neural connections that are no longer necessary to make space for new memories.
Read More: Lack of Sleep Could be Causing an Increase in Mental Health Disorders
Processing Memories During Sleep
The recent study adds a new dimension to memory processing, expanding upon prior research that has mostly focused on sleep’s role in preserving past memories through specialized neurons called engram cells. Using an imaging system on the brains of mice, researchers aimed to see how neurons behaved during sleep and handled information from learning experiences, according to a statement.
The researchers uncovered two simultaneous processes during sleep, after the mice had undergone a learning experience. First, the engram cells that initially encoded a learning experience were reactivated, indicating that consolidation was taking place. Meanwhile, another group of neurons was also synchronizing during post-learning sleep. These cells were later found encoding a new, different learning experience, and were therefore named “engram-to-be” cells.
To determine the source of engram-to-be cells, the researchers created a neural network model that simulated activity in the hippocampus. The model revealed two mechanisms at work — synaptic depression and scaling, both of which regulate the strength of neuron connections during sleep. Since engram cells and engram-to-be cells were both activated during post-learning sleep, the researchers say a neural connection exists between past and future memories.
The Importance of Sleep
The study’s results suggest that the quality of sleep may impact how well we’re able to learn new information. Understanding how sleep lays the groundwork for future memories could affect approaches related to education, cognitive enhancement, and the treatment of memory disorders, the researchers say.
Poor sleep is known to impede memory processing, but it may also leave the brain unprepared to retain information from learning experiences in the future. Ultimately, sleep keeps us fit to remember experiences, a necessary function for a healthy life.
“We want people to understand that sleep is not just about rest — it plays a crucial role in how the brain processes information,” said Kaoru Inokuchi, a professor at the University of Toyama who led the research team, in a press release. “With that in mind, we hope everyone will begin to value sleep more and use it as a way to improve their overall quality of life.”
Read More: Sleep’s Surprising Role in Strengthening Long-Term Memory
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Nature Communications. Parallel processing of past and future memories through reactivation and synaptic plasticity mechanisms during sleep
Cleveland Clinic. Hippocampus
Yale School of Medicine. Sleep’s Crucial Role in Preserving Memory
Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.
