Why we remember almost nothing from infancy: Mouse study offers new clues
Why can most people remember little or nothing from their earliest years? A new study in mice suggests the answer may lie in how the brain's memory circuits develop after birth, with early memories forming in a system that is highly connected but lacks the precision needed for long-term storage, Qazinform News Agency correspondent reports, citing LiveScience.
The research, published in Nature Communications, examined the hippocampus, a brain region essential for learning and memory. Scientists focused on an area known as CA3, which plays a key role in storing and retrieving memories. By analyzing brain tissue from mice at different stages of development, they discovered that the hippocampus is not built from scratch after birth. Instead, it begins with an unusually dense web of neural connections that is gradually refined as the brain matures.
The researchers found that shortly after birth, neurons in the CA3 region are connected in a dense and largely random network. As the animals grow, many of these connections are eliminated, leaving behind a smaller but more organized system. The findings support the idea that the brain starts with a "full slate" rather than a blank one, with experience helping shape and strengthen the most useful connections over time.
The study also revealed that neurons behave differently early in life. In newborn mice, a single connection between neurons was often strong enough to trigger activity. As the brain matured, neurons required signals from multiple connections before firing, making memory networks more selective and reducing overlap between different experiences.
According to the researchers, this could help explain why memories formed in infancy are difficult to recall later in life. When neural networks are overly connected and easily activated, different experiences may be stored using overlapping patterns of activity, producing memories that are broad rather than highly detailed. As the brain develops, pruning excess connections allows memories to become more distinct and stable.
The team also used computer models to test how these developmental changes affect memory. The simulations suggested that the transition from dense, highly excitable networks to sparser and more structured ones improves the brain's ability to store and retrieve memories efficiently.
Earlier, Qazinform News Agency reported that a Vitamin B12 compound shows promise against deadly brain cancer.