Sleep 'resets' neurons to help brain take on new memories

• One of the main functions of the human brain is to create memories.
• A number of lifestyle factors can help improve a person’s ability to create memories, including proper sleep.
• Researchers from Cornell University have found that during sleep the hippocampus region of the brain goes ‘silent,’ allowing neurons to ‘reset’ so they can help create new memories the next day, via a mouse model.

One of the main functions of the human brain is to create memories — the ability to retain and recall information over time.

Memories allow us to remember important events in our lives, the faces of those we know, and give us the ability to learn.

Special cells in the brain called neurons help create memories, which are then stored in the hippocampus area of the brain.

A number of lifestyle factors can help improve a person’s ability to create memories, including following a healthy diet , exe r cising , meditation , and getting enough sleep .

“We have a bulk knowledge about sleep being better for our body to rest, for our memory to be better, but we do not yet understand all the details of how this happens,” Azahara Oliva, PhD , assistant professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences at Cornell University explained to Medical News Today .

“Once we start cracking the neural processes that are important for these many different things, we could use that to reverse detrimental conditions, such as memory impairment, during sleep,” she added.

Oliva is the corresponding author of a new study recently published in the journal Science , which found that during sleep, the hippocampus goes “silent” and allows neurons to “reset,” making them available to create new memories the next day, via a mouse model.

“We want to see what exactly the brain is doing during sleep that favors or disfavors memory,” Oliva said. “We [spend] about a third of our life sleeping — this is a lot of time. Understanding the relation between sleep and memory will provide insights into how we can tackle detrimental memory conditions.”

How do neurons ‘reset’ during sleep?

The researchers explained that there are three main regions of the hippocampus: CA1 , CA2 , and CA3 .

Using a mouse model, the scientists discovered that while the neurons in areas CA1 and CA3 were very active during daytime learning, those regions became “silent” while the mice slept.

“We realized there are other hippocampal states that happen during sleep where everything is silenced,” Oliva said in a press release . “The CA1 and CA3 regions that had been very active were suddenly quiet. It’s a reset of memory, and this state is generated by the middle region, CA2.”

This “silencing” of areas CA1 and CA3 allow neurons to “reset” during sleep.

“During our experience, a few neurons become highly active,” Olivia explained. “The same neurons ‘work hard’ during sleep to imprint this experience into memory. What we found is that for these neurons to be able to imprint these memories, they also need breaks or a ‘reset.’ Without these breaks, the neurons are not able to make proper memories.”

Opening treatment options for memory-related conditions

Thanks to the findings of this study, Oliva and her team believe they now have some tools to help potentially boost memory. Such strategies could eventually help doctors tackle diseases characterized by memory issues, such as Alzheimer’s disease .

Additionally, scientists believe these findings might help one day allow doctors to remove negative or traumatic memories from a person to assist with conditions like post-traumatic stress disorder (PTSD) .

“We now know which particular neurons and through which particular neural circuits are responsible for different neural processes, both important for memory, like consolidation and resetting,” Oliva said. “That will facilitate the specificity that we can gain when treating different types of detrimental memory conditions.”

Commenting on the next step in this research, she told MNT :

“We want to know how exactly the brain coordinates high memory demands. What happens when there is more than one experience? At the end of the day, during most of our life we [always have] many things we want to learn and remember.”

Memory research: Hippocampus remains an area of interest

After reviewing this study, Manisha Parulekar, MD, FACP, AGSF, CMD , director of the Division of Geriatrics at Hackensack University Medical Center, co-director of the Center for Memory Loss and Brain Health at Hackensack University Medical Center, and associate professor at Hackensack Meridian School of Medicine in New Jersey, told MNT that it provides insight into how sleep “resets” the brain for new learning, offering a potential explanation for why we need sleep and how it impacts memory consolidation.

“Understanding the role of the CA2 region in silencing and resetting memory circuits could lead to therapies that enhance memory consolidation and prevent further cognitive decline in patients with dementia and Alzheimer’s disease,” Parulekar explained.

“Additionally, optimizing sleep quality through interventions like cognitive-behavioral therapy for insomnia could be crucial in managing these conditions,” she noted.

Parulekar said that it is important for researchers to continue to find new ways in which sleep affects the brain as further research is needed to understand individual variations in sleep patterns and brain activity to personalize these potential therapies.

“Exploring the contributions of other sleep stages and developing noninvasive techniques to modulate brain activity during sleep are also important areas for future investigation,” she continued.

“Translating these findings into clinical trials to test the efficacy of interventions targeting the CA2 circuit or sleep quality in patients with dementia and Alzheimer’s disease is crucial,“ said Parulekar. “Developing personalized approaches based on individual sleep patterns and brain activity and conducting studies to evaluate the sustained benefits and potential risks of these interventions are essential next steps.”