Researchers at the Korea Advanced Institute of Science and Technology (KAIST) have identified, for the first time in the world, a neural switch in the brain that selectively retrieves the most recent memories. The study reveals the principle by which the brain selects necessary information between past and new memories, presenting new possibilities for treating memory decline and reduced cognitive flexibility.
According to KAIST on Monday, a research team led by Professor Han Jin-hee of the Department of Biological Sciences became the first in the world to demonstrate that a specific neural circuit plays a key role in switching between past and recent memories to select up-to-date information suited to a given situation.
Until now, how the brain distinguishes and switches between memories had long remained unknown. The research team focused on the medial septum, located deep within the brain. The medial septum regulates the activity rhythm of the hippocampus and serves a coordinating role that helps the brain effectively store and retrieve information.
The study found that when specific neurons in the medial septum send signals to the medial entorhinal cortex—the brain region that processes memory information and transmits it to the hippocampus—the brain better recalls recent memories. Conversely, when the research team artificially blocked this neural circuit using light, experimental animals failed to utilize the latest information and instead behaved according to past patterns. The neural activity of the hippocampus, which plays a key role in memory storage, also reverted to its previous state.
In addition, the longer the brain maintained an "online" state of actively processing information, the better it recalled recent memories, whereas frequent switching between online and offline states significantly reduced memory retrieval capacity. The research team expects that this discovery could lead to the development of new treatment technologies to improve memory decline in patients with degenerative brain diseases such as dementia and Alzheimer's.
"Previously, memory retrieval was understood simply as a process of replaying stored traces, but through this study, we have demonstrated that the brain has a regulatory system that actively selects the latest information among competing memories," Professor Han said.
