The human brain is very good at forgetting, a fact that I was recently reminded of when my bank asked me to choose from a series of “security questions” as part of an account upgrade. What was the name of my third-grade teacher? What was the name of the street my school was on? What city was my mother born in? I was astonished at how little of this kind of thing remained in my memory bank.
Forgetting this kind of explicit memory comes easily, but there’s another kind of memory we’re not so good at erasing. Memories of fearful experiences seem to stay with us forever. To the extent that their impact fades over time, it’s not because we forget them, but that our brains gradually suppress them. They’re forgotten, but not gone. And they can cause problems for people suffering from emotional trauma, when buried memories come roaring back to inflict pain all over again.
It would be better if the brain were able to forget some kinds of fearful memories just it can things like names and phone numbers – and a recently published paper presents evidence that might just be possible. Researcher Nadine Gogolla and colleagues demonstrated that as the brain of a baby mouse matures, its ability to form permanent fear memories develops at the same time as a net-like structure forms in the amygdala, where emotions are processed and fear-related memories are stored. Made of proteins called chondroitin sulfate proteoglycans, this “neural net” structures seem to prevent memories from being erased. When they’re disrupted by a drug, mice are more likely to lose those memories.
The finding points the way to a possible therapy for human fears: a drug that would alter the formation or functioning of the “neural net” and thereby allow people to shed troubling and disturbing memories. It’s still a long way off, but the research indicates that it could at least be possible.