Remembering our earliest experiences, such as our first attempt at crawling or the first taste of solid food, may seem impossible. However, new research from Trinity College Dublin sheds light on the science behind “infantile amnesia” and how it affects our ability to recall these precious memories.
This study, involving immunological models of autism spectrum disorder (ASD) in mice, has revealed the significant role that a mother’s immune system plays in moderating access to memories of life’s earliest moments. It’s even suggested that understanding this amnesia could help explain why some individuals with autism have exceptional memory abilities, recalling events from ages most of us have forgotten.
Trinity College Dublin neuroscientist Tomás Ryan explains, “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. As a society, we assume infant forgetting is an unavoidable fact of life, so we pay little attention to it.”
While our mental autobiography typically begins between our second and third birthday, our brains are fully capable of forming memories from an even earlier age. However, researchers are left to consider the mechanisms at work making those memories inaccessible. Clues have emerged, such as the prevention of infantile amnesia through pharmaceutical interventions targeting specific neurotransmitters and the timed use of corticosteroids.
In the study, researchers turned their attention to the environmental shifts governed by the mother’s immune system, which have been implicated in influencing the development of neurological conditions such as ASD and schizophrenia. The use of young and adult mice conditioned to fear an electrical shock revealed that male offspring of mothers who experienced immune responses mid-pregnancy showed signs of remembering fearful events for longer periods, shedding light on the role of maternal immune activation in moderating early memories.
Further tests using transgenic mice revealed critical differences in the structures and sizes of memory neurons in the brains of male offspring born to mothers lacking a specific immune protein. This has provided insights into the mechanisms at work behind infantile amnesia and how these early developmental trajectories affect memory storage and retrieval in infancy.
This groundbreaking research, published in Science Advances, has opened up new avenues for understanding infantile amnesia and its effects, with potential implications in educational and medical settings.
