Early life stress and regulation of inhibition and forgetting

Early life adversity in humans is associated with increased risk of developing mental illnesses such as depression and anxiety. Given the importance of these first few years of life, it is interesting that most adults fail to recall autobiographical events from their early childhood years. Infantile amnesia is the term used to describe this phenomenon of accelerated forgetting during infancy, and it is not unique to humans.

In fact, infantile amnesia has been observed in every altricial species examined, that is, all animals that experience extensive post-gestational development and care-giving. Many investigations into infantile amnesia have used Pavlovian fear conditioning in rats as a model of learning and memory.

While adult rats exhibit excellent memory retention following just a single conditioning episode, infant rats rapidly forget fear associations over short intervals. Recently it has been shown that exposure to early life stress improves retention of learned fear in infant rats.