The first and most important thing to note is that all the results currently available are from experiments conducted on mice. Scientists discovered this in rodents The brain stores at least three copies of a particular memory and encodes it in different places body These copies are encoded by different groups of neurons in the hippocampus, an area of ​​the brain critical for learning and memory. The copies vary in when they are created, how long they exist, and their ability to change over time.

Detail

• In a new study published Aug. 16, scientists show that when mice encode new memories, they first create neurons called precocious neurons. These neurons are responsible for storing a long-term copy of the memory that is initially weak but grows stronger over time.
• Next come the intermediate neurons, which are more stable from the start.
• After them, late-developing neurons appear, which encode very strong copies of the memory from the very beginning, but this strength fades over time.

The researchers discovered this by examining the activity of different groups of neurons in the hippocampus after mice performed various memory tasks, which involved learning to avoid dangerous situations, such as receiving electric shocks to their paws, before being confronted with the same task later.

How these three groups of neurons operate on different timescales could help explain how the brain organizes memory over time, the study authors say. However, it is still unclear exactly how these neurons interact with each other to facilitate this, said study co-author Flavio Donato, a professor of neurobiology at the University of Basel in Switzerland.

In particular, memories stored by later-born neurons were more flexible or malleable than memories from earlier-born neurons. This suggests that information stored in the early stages of memory formation (when early neurons dominate) remains fairly stable over time, whereas memories stored later are more easily distorted by new information.

What about people?

Donato believes that if the same phenomenon occurs in humans, the discovery could one day lead to new treatments for certain disorders. For example, in post-traumatic stress disorder (PTSD), people experience intrusive memories—unwanted, disturbing memories of a traumatic event. Perhaps a drug could be developed that would activate late neurons that are more plastic and therefore more receptive to psychotherapy.

In people with memory loss due to dementia, another type of medication can stimulate the activity of early neurons that store information more tightly.

Broadly speaking, such treatments allow the properties of memory to be manipulated by selecting which types of neurons in the brain are used to encode it.