The Persistence of Memory and the Neurological Origins of Fear

According to an article by Roger L. Clem and Richard L. Huganir published recently in Science Magazine, it is possible to erase fear memories.

When I saw the headline about “Fear Memory Erasure,” my interest was immediately piqued. The things that one obsesses over in private invariably make it into one’s books…which is to say, memory and forgetting were bound to worm their way into one of my books at some point.

Toward the end of The Year of Fog, Abby wishes that she could take a “forgetting pill,” because all of her familiar beloved places in San Francisco are tinged with the difficult memories of her search for Emma. She would like to forget the year that she has just endured, she would like to forget the intense emotions, and the fear, all of it. Because to remember a thing is to relive it, for better or worse.

As it turns out, selective forgetfulness isn’t just a fantasy. Here’s the abstract for the article:

Traumatic fear memories can be inhibited by behavioral therapy for humans, or by extinction training in rodent models, but are prone to recur. Under some conditions, however, these treatments generate a permanent effect on behavior, which suggests that emotional memory erasure has occurred. The neural basis for such disparate outcomes is unknown. We found that a central component of extinction-induced erasure is the synaptic removal of calcium-permeable amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) in the lateral amygdala. A transient up-regulation of this form of plasticity, which involves phosphorylation of the glutamate receptor 1 subunit of the AMPA receptor, defines a temporal window in which fear memory can be degraded by behavioral experience. These results reveal a molecular mechanism for fear erasure and the relative instability of recent memory.

It’s heady stuff, not particularly friendly to the untrained ear, and half of it went over my head; but one thing that stood out to me is the role of the amygdala (Abby delves into this small but powerful structure in the brain in her attempts to understand the complex workings of memory. I delved into it by visiting a neurologist, an odd and infinitely entertaining man with a glamor shot of himself in full medical regalia on the wall of his office, a man who sucked on Mentos during our entire visit, prior to pointing out the rascally amygdala on a model brain perched on his desk). The removal of a particular substance from the amygdala seems to be the key to the removal of fear and the “instability of recent memory.”