Like a computer system with built-in redundancies, the brain uses three different sets of neurons to store a single memory, according to a study that suggests a finding that could one day help mitigate painful memories in people who have experienced trauma.

By imaging mouse brains, researchers at the University of Basel’s Biozentrum were able to observe what happens when a new memory is formed. They found that the rodents’ brains activated three different groups of neurons to record the memory. The first are known as early-born neurons, and are the first to develop as a fetus grows. At the other end of the spectrum are late-born neurons, which only show up late in embryonic development. In between are neurons that form somewhere in the middle of growth in the womb.

The imaging study found that when the new memory is stored in the premature neurons, it is initially difficult to recall but becomes stronger over time.

The copy of the memory stored in the late-born neurons, on the other hand, was very strong at the beginning but faded over time to the point where the brain could no longer access it. In the middle, the memory copy showed a higher degree of stability than in the other neuronal groups.

University of Basel, Biozentrum

“The challenge the brain faces in terms of memory is quite impressive,” says Flavio Donato, head of the research group at the Biozentrum. “On the one hand, it has to remember what happened in the past so that we can understand the world we live in. On the other hand, it has to adapt to the changes that are happening all around us, and that also applies to our memory, so that we can make the right decisions for our future.”

With their new understanding, the researchers were able to gain deeper insights into how memories are formed and accessed. It’s important to note that while the study was conducted on mice, their brains are often used as surrogates for our own in neuroscience because they have 75 different cell types in their cerebral cortex, which is equivalent to humans. Still, the results are mouse-specific at this point.

Still, the researchers believe their work could have implications for treating people damaged by a traumatic event. They say their work shows how it could alter memories in the brain. For example, if a memory is fresh, meaning the late-forming neurons are activated, it could still be altered before it is passed on to the middle and early-forming neurons for storage. Once the late-forming neurons are activated and the memory is stored there, it becomes increasingly difficult to alter it. Basically, the longer a memory is stored in the brain, the harder it is to alter it.

“The dynamics of memory storage in the brain is evidence of the brain’s plasticity, which underlies its enormous memory performance,” says the study’s lead author, Vilde Kveim.

Understanding this plasticity through the work of Kveim and his team could one day help scientists understand how to help people access memories they thought were lost forever, or how to soothe painful memories that pathologically intrude into their daily lives.

The team’s work was published in the journal Science.

Source: University of Basel