Where do traumatic memories live? A fascinating study about trauma and the brain.
I feel like a broken record sometimes when I tell people that the brain doesn't always process or retrieve traumatic memories in quite the same way it does ordinary ones. Sometimes, when patients ask me why they are reminded of something traumatic—like a car accident or military combat—during seemingly random moments in their lives today, I come back to that point about the uniqueness of traumatic memories. Ordinary stuff like the name of your first-grade teacher might be connected through your hippocampus, a brain region important for organizing memories, with other relevant context from that part of your life story. Scarier, more disruptive stuff isn’t always organized like this, for you to recall when you want.
But then, where do traumatic memories live? It’s become a cliché to say that memory is located in the body, which, in a way, is true; parts of us feel connected to the past even when we are not fully reliving it. This is sometimes why people who were hurt in combat or abused as kids feel pain in parts of their bodies that were affected, even when they are just reminded of those incidents. But of course, trauma is more complicated than that.
I was impressed when I read about a brain imaging study at Yale University and The Icahn School of Medicine at Mount Sinai, which offered an answer—if not the only one—to this question. Researchers studied brain scans of 28 people with PTSD who were asked to recall neutral, sad, and traumatic memories from their own lives. They found that traumatic memories produced a distinctive pattern of activity in a part of participants' brains called the posterior cingulate cortex—P.C.C. for short. The P.C.C. is a region towards the middle and back of our brains that is active when we daydream, think about ourselves, and recall personal experiences. The findings raise interesting questions about what might be happening when people whose minds are wandering feel triggered by a sensory cue, like hearing a door slam or smelling the kind of tomato sauce their mother used to make in their childhood home.
One (admittedly oversimplified) way of looking at this is: If some of the clothing in your closet is organized and hung up, that’s sort of like your ordinary, or neutral memories, which you can pull out and use just like you can wear a shirt you’ve organized away neatly. Traumatic memories are like the pile of crumpled-up clothes in a chaotic pile in the closet’s back corner, along with a bunch of other stuff, like books, or maybe a Hershey bar you forgot you had in one of the pockets. You might reach for the book and come across an old item of clothing you’d forgotten about, just like introspection can put you in touch with the past in ways you might not expect.
As for introspection, which happens a lot in therapy, I also wonder about exactly what happens when I ask patients to examine some of their own attitudes, beliefs, behaviors, and feelings. When does that kind of self-reflection lead to unexpectedly stumbling on a traumatic memory? The article didn’t mention that, but it feels intuitively true to me that if you’re deep in thought, it would be easy to stumble across reminders of events that have been so very stressful that they are hard to forget.
Conversely, in my own clinical practice, I have noticed that more structured activities that engage the mind with your surrounding environment—activities like playing board games, taking a martial arts class, or learning a foreign language--can help to keep traumatic memories from creeping up unexpectedly, at least for a little while; these kinds of activities keep the mind from wandering as easily, after all.
Regardless of the mechanics of how we access trauma, I do like knowing that how we process—or don’t process—memories matters. If we work to tap into old memories—through EMDR, prolonged exposure therapy, or some other technique that helps us to keep one foot in the present--then it is possible to change the way we store and retrieve memories, and therefore gain more control over our moment-to-moment experiences. Not that anything is a magic bullet. You probably know as well as I do that therapy is hard work. But when memories do find a route to a new home, change is certainly possible.
