Cornell Study Reveals Brain's Mechanism for Resetting Memory during Sleep
TEHRAN (Tasnim) – A new study from Cornell University has uncovered a mechanism in the brain that allows for memory resetting during sleep, ensuring continuous learning without overloading the brain's capacity.
Researchers found that during sleep, the brain consolidates memories by repeating patterns of neuronal activity in the hippocampus, which are stored in the cortex.
The study, titled "A Hippocampal Circuit Mechanism to Balance Memory Reactivation During Sleep," demonstrates that certain parts of the hippocampus go silent at specific times during deep sleep, allowing neurons to reset.
"This mechanism could allow the brain to reuse the same resources, the same neurons, for new learning the next day," explained Azahara Oliva, assistant professor of neurobiology and behavior and the study's corresponding author.
The hippocampus, divided into three regions—CA1, CA2, and CA3—has been well studied in areas CA1 and CA3, which are involved in encoding memories related to time and space. However, the study highlights the less understood CA2 region, which appears to generate the silencing and resetting of the hippocampus during sleep.
Using implanted electrodes in the hippocampi of mice, researchers observed neuronal activity during learning and sleep. They found that during sleep, neurons in the CA1 and CA3 regions reproduced the same patterns developed during learning. However, the researchers also noted periods when these regions became silent, allowing for memory reset.
"We realized there are other hippocampal states that happen during sleep where everything is silenced," said Oliva. "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."
The study also uncovered that the brain has parallel circuits regulated by two types of interneurons—one responsible for memory regulation and the other for memory resetting.
Researchers believe this understanding could lead to ways to enhance memory or even erase traumatic memories, which could benefit conditions like Alzheimer's disease and post-traumatic stress disorder.
The findings provide insight into why sleep is essential for maintaining cognitive function and memory, with Oliva noting, "We show that memory is a dynamic process."
The study was funded by the National Institutes of Health, a Sloan Fellowship, a Whitehall Research Grant, a Klingenstein-Simons Fellowship, and a New Frontiers Grant.