Why some rape and trauma survivors have fragmented and incomplete memories

First, let’s consider the prefrontal cortex. This part of our brain is responsible for “executive functions,” including focusing attention where we choose, rational thought processes and inhibiting impulses. You are using your prefrontal cortex right now to read this article and absorb what we’ve written, rather than getting distracted by other thoughts in your head or things going on around you. But in states of high stress, fear or terror like combat and sexual assault, the prefrontal cortex is impaired – sometimes even effectively shut down – by a surge of stress chemicals. Most of us have probably had the experience of being suddenly confronted by an emergency, one that demands some kind of clear thinking, and finding that precisely when we need our brain to work at its best, it seems to become bogged down and unresponsive. When the executive center of the our brain goes offline, we are less able to willfully control what we pay attention to, less able to make sense of what we are experiencing, and therefore less able to recall our experience in an orderly way.

Inevitably, at some point during a traumatic experience, fear kicks in. When it does, it is no longer the prefrontal cortex running the show, but the brain’s fear circuitry – especially the amygdala. Once the fear circuitry takes over, it – not the prefrontal cortex – controls where attention goes. It could be the sound of incoming mortars or the cold facial expression of a predatory rapist or the grip of his hand on one’s neck. Or, the fear circuitry can direct attention away from the horrible sensations of sexual assault by focusing attention on otherwise meaningless details. Either way, what gets attention tends to be fragmentary sensations, not the many different elements of the unfolding assault. And what gets attention is what is most likely to get encoded into memory.

The brain’s fear circuitry also alters the functioning of a third key brain area, the hippocampus. The hippocampus encodes experiences into short-term memory and can store them as long-term memories. Fear impairs the ability of the hippocampus to encode and store “contextual information,” like the layout of the room where the rape happened. Fear also impairs its ability to encode time sequencing information, like whether the perpetrator ripped off a shirt before or after saying “you want this.”