Most people have little to no recollection of the first years of their lives, and this phenomenon has long been known as childhood amnesia. A new scientific study offers an explanation suggesting that early forgetting is not a defect in brain function but an important mechanism of its normal development.
The Role of Microglia in Memory Formation
Key participants in the process turned out to be microglial cells — elements of the brain's immune system. They are responsible for "cleaning" neural networks by removing excess or unused synapses and helping to form new connections. During the period of active brain growth, this work is particularly intense.
Scientists have hypothesized that microglia may limit access to early memories, thereby freeing up resources for learning and adaptation in a rapidly changing environment.
Animal Experiments
To test this theory, researchers conducted experiments on young mice. The animals were trained to associate a specific location with a mild stressor. After this, the activity of microglia was artificially reduced in some of the mice.
The results showed that these mice retained the memory of the stress significantly longer than the control group. Their memory characteristics began to resemble those of adult individuals, confirming the link between microglial activity and the process of forgetting.
Forgetting as a Development Strategy
Additional experiments demonstrated that microglia help the brain avoid information overload. This mechanism allows for the filtering out of details that are not relevant for further development and focuses on forming more stable and useful neural networks.
Interestingly, in pups born to mothers with an active immune system, childhood amnesia was less pronounced or absent altogether. When microglial activity was artificially suppressed, the memory of such animals reverted to a "child-like" state.
What This Means for Humans
So far, research has only been conducted on animal models; however, the findings open up prospects for studying memory in humans. Scientists plan to determine which signals activate or suppress microglia and whether it is possible to deliberately influence these processes.
Understanding the mechanisms of forgetting may aid in the study of age-related memory impairments and neurodegenerative diseases. It is possible that some "lost" memories actually remain in the brain but are temporarily inaccessible to consciousness.
