How vividly do your remember your childhood? For me there are snatches, here and there, but a lot of those early experiences are gone.

New research by Sheena Josselyn and Paul Frankland  at the Hospital for Sick Children in Toronto, Canada might sheds some light on why that happens, suggesting newly formed neurons can actually dislodge old info.

According to an article about the findings in Nature, the pair studied neuron growth in the hippocampus region of the brains of mice. The hippocampus is a region involved in memory formation. We grow new neurons there throughout our lives, although we grow them more quickly when we are young.

Past research has shown that boosting neuron growth before learning can boost memory in mice. The new research, however, suggests it can also degrade previously learned memories.

The experiment tested how long mice would remember an electric shock. The older mice remembered and showed fear when put in the same situation much longer than the younger mice, a condition called “infantile amnesia” that has also been observed in humans. Suppressing the growth of new neurons in the young mice made them retain the information longer.

“More neurons increase the capacity to learn new memories in the future,” Josselyn says. “But memory is based on a circuit, so if you add to this circuit, it makes sense that it would disrupt it.”

Josselyn theorizes this process has a useful purpose, clearing out old memories to make room for new ones.

Makes sense. Just wish we could pick and choose what we forget. I’d trade a few of my vividly remembered episodes of BJ and The Bear for more sunny days of play and nearly forgotten childhood friends.

[Source: Nature]

Image: Submersion in The Lethe, a Gustave Doré illustration for Dante’s The Divine Comedy


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