Baby Memories Can Return When Triggered, Study Says

It's often believed that it's much harder to remember memories from childhood. This is why memories from being a toddler are almost impossible to remember. However, recent studies show that the right triggers can force these memories back, at least on mice.

Alessio Travalgia at New York University told New Scientist that most people can't remember the first two or three years of their lives. Some that claim to do so often have inaccurate memories or based on stories people tell them.

Interestingly, the really important stuff stays with us, such as how to move or communicate and what things we like. So why won't autobiographical memories stay?

According to New Scientist, others say the incredible growth of new neurons during early childhood interfere with memory storage, meaning our earliest memories may be lost forever. 

Travalgia and his colleagues did a study on rats that they believe should also suffer from "infantile amnesia." Young, 17-day-year-old rats (which, in rat days, is about a two- to three-year-old child) could learn to associate one side of a box with shock. However, these memories would be gone within a day. Older rats that may participate in the experiment may remember these for a long time.

Interestingly, the right "reminder" may help young rats remember these lost memories. Once the little rats forgot which side had the shock, they reintroduced the concept. And suddenly, their memories were back.

This suggests that the memories may still be there, but they are inaccessible. Travaglia said this may apply to humans as well and that the "off days" we experience may result from the subconscious reactivation of unpleasant memories. Meaning something inside us may be forcing unpleasant memories we don't even remember we have.

Andril Rudenko and Li-Huei Tsai of MIT praised the study, citing it "breaks new ground" as it shows that very early memories in mammals are not really lost but may, in fact, be latent and can be recalled later. 

The researchers also found out that several proteins either increased or decreased in number in the hippocampi of rats, which is vital for memory. These changes are triggered by learning and not time.

One of the proteins, called BDNF, seemed to be important, since when young rats were injected with this, it prevented their memories from being lost. It seems, medically wise, this method may help children retain their first memories as well.