'Lost' infant memories can be reinstated later in life, thanks to specific mechanisms in the hippocampus, the brain's memory centre.

Humans and other animals are often unable to recall early-life events, but these experiences can still affect the brain and behaviour later in life. To figure out how, Cristina Alberini at New York University in New York City and her colleagues administered electric shocks to the feet of infant rats and showed that the animals seemed to lose this memory within 24 hours. However, when presented with contextual reminders and another footshock several days later, the rats behaved as if they remembered the initial shock. The researchers pinpointed specific mechanisms in the hippocampus — including a shift in the relative levels of two forms of a receptor for a molecule called NMDA — that are involved in the formation and storage of early-life memories.

The results suggest that the hippocampus goes through a critical period of rapid development during infancy.

Nature Neurosci. http://dx.doi.org/10.1038/nn.4348 (2016)