Researchers at the Korea Advanced Institute of Science and Technology (KAIST) discovered a neural circuit that determines whether a brain retrieves recent or past memories [1].
This discovery provides a potential mechanism for understanding why individuals with dementia often struggle with recent memories while retaining older ones. By identifying the specific biological switch that controls memory selection, scientists may find new pathways to treat cognitive decline.
The team, which included Dr. Kim Moo‑jun and Prof. Han Jin‑hee from the KAIST Department of Biological Sciences, utilized optogenetics to conduct the study [1]. This technique allows researchers to use light to switch specific neurons on or off. In this experiment, the scientists deactivated a neural circuit linking the medial septum and the medial entorhinal cortex in mice [1].
When this specific circuit was switched off, the mice retrieved past memories instead of more recent ones [1]. The results suggest that this circuit acts as a gatekeeper for memory retrieval. Without the circuit's active regulation, the brain defaults to older information rather than the most current data.
Dr. Kim Moo‑jun said the function of the neural circuit is to determine which memory — a past one or a recent one — will be selectively retrieved [1]. This process of selection is critical for normal cognitive function, and daily navigation of information.
Prof. Han Jin‑hee said the discovery may help solve the mystery surrounding patients with dementia [1]. The research highlights how the disruption of such circuits could lead to the characteristic memory patterns seen in neurodegenerative diseases.
“The research highlights how the disruption of such circuits could lead to the characteristic memory patterns seen in neurodegenerative diseases.”
The ability to artificially manipulate the retrieval of specific memory layers suggests that memory loss in dementia may not always be a matter of 'deleted' data, but rather a failure in the retrieval mechanism. If the circuit between the medial septum and medial entorhinal cortex is damaged or dysfunctional, the brain may lose its ability to prioritize recent information, effectively locking the patient into a state of recalling only distant past events.
