The Fuzzy Memories of Infancy: Immune System and Memory
Do you ever wonder about your very first memories, back when you were just a baby? Most people can’t recall those early experiences, but a new study suggests that our brains might still have those memories stored away. Research on rats has shown that memories of infancy might be accessible, and a recent study from Trinity College Dublin has revealed the surprising role a mother’s immune system plays in moderating access to these memories.
The study, which involved immunological models of autism spectrum disorder (ASD) in mice, found that infantile amnesia, or the inability to remember early experiences, may be influenced by the mother’s immune system. Not only does this shed light on how memories remain accessible in some minds and vanish in others, but it also helps to explain why some people with autism have exceptional memory.
Neuroscientist Tomás Ryan from Trinity College Dublin explained that “infantile amnesia is possibly the most ubiquitous yet underappreciated form of memory loss in humans and mammals.” Despite its widespread relevance, little is known about the biological conditions underpinning this amnesia and its effect on the engram cells that encode each memory.
The research focused on the environmental shifts governed by the mother’s immune system, specifically maternal immune activation (MIA). By comparing mice born to mothers who experienced immune responses mid-pregnancy, the researchers found that the male offspring of these mothers showed signs of social behavior deficits similar to people with ASD and had evidence of remembering fearful events far longer than their sisters and control mice.
Further testing using transgenic mice carrying a gene that labeled memory neurons revealed critical differences in the structures and sizes of the MIA males’ engrams in a region of the brain known to be critical in memory formation.
What is particularly interesting is the role of a small immune protein called cytokine IL-17a in the process. Male mice born to mothers engineered without this protein still experienced infantile amnesia when the same immune responses were provoked during pregnancy.
Neuroscientist Sarah Power, the lead author of the study, explained, “Our brains’ early developmental trajectories seem to affect what we remember or forget as we move through infancy. We now hope to investigate in more detail how development affects the storage and retrieval of early childhood memories, which could have a number of important knock-on impacts from both an educational and a medical perspective.”
This groundbreaking research, published in Science Advances, has brought us a step closer to understanding how our earliest memories are formed and accessed in the brain. This could have significant implications not only for understanding memory and memory-related conditions but also for educational and medical practices.