Scientists discover how the brain adds new information to old memories

Published on 04/10/2026 - 5:00 GMT+2•Updated 8:34

Imagine, for instance, a building site in your neighbourhood. The human brain is capable of keeping track of three key stages of it: the original state before the work began, the construction itself, and the final result once everything is finished. But how does it manage not to mix up those three memories?

The Institute of Neurosciences, a public research centre run jointly by the CSIC and Miguel Hernández University, believes it has identified this neurological mechanism in a new study published in the journal "PLOS Biology" (source in Spanish).

The team from its Neural Network Plasticity Laboratory believes the brain uses a region of the hippocampus, the dentate gyrus, which is dedicated to forming new memories. There, a specific type of neuron inhibits the activity of other cells to help integrate new experiences.

To test this, the team altered this inhibitory process to a greater or lesser extent in mice. "When inhibition was lower than usual, their behaviour was more in line with better memory retrieval and more detailed recollection," explains Encarni Marcos, co-lead author of the study and head of this line of research at the IN CSIC-UMH.

However, there is no single optimal level of inhibition for preserving as much information as possible. The computational model used in the experiment showed that when the memory load is low, reduced inhibitory activity is beneficial, but that this is no longer the case when the amount of information increases significantly.

The study suggests that, depending on the type of memory, the dentate gyrus of the hippocampus may either facilitate the incorporation of new inputs or, conversely, keep an existing memory more stable in the face of new stimuli. This will depend on the contextual importance, or what the team describes as the demands of the task. "What we take from these results is that there is a mechanism that dynamically adjusts the mode of operation using inhibition," Marcos concludes.