In this study of Lisa Genzel, published in eLife, researchers found that when we increased the brain's ability to change and adapt (plasticity) in a specific area called the prelimbic cortex using a virus, it improved the formation of new memories after just one learning experience. However, this improvement came at a cost. It also caused interference with the storage of semantic-like memories, which is the knowledge that you have. Genzel: “Your brain is quite optimal as it is. If you try to enhance it, you may actually lose something.“
To understand the effects of this manipulation, researchers used a technique called electrophysiological recordings, which allows us to measure the activity of brain cells. The study showed that the manipulated brains had shorter periods of deep sleep, fewer slow brain waves called delta waves, and reduced activity of brain cells. On the other hand, enhanced interaction between the hippocampus and the cortex was observed.
These findings provide the first experimental evidence supporting the long-held idea that the cortex has a protective mechanism for existing memories. This also shows that by changing the brain's ability to adapt, it can affect both the formation and consolidation of memories.