Trauma and Memory Loss: Part 1
Trauma significantly impacts how our brains form, process, store, and recall memories. Let’s break it down.
The common belief is that memories are formed by information coming into your brain and being filed away. That information is like a photocopy, an exact replica of the experience. And like a piece of paper, the writing is freshest when first printed and then fades over time. But that’s not actually how it works.
Information comes into your brain through all sorts of avenues: sights, sounds, smells, taste, touch, temperature, and more. Words, images, sensations, and emotional reactions all provide different information and are processed through different parts in your brain. For everyday interactions some of that information will make it to long term memory storage, but most of it will be lost. This is not a conscious choice, but rather the result of various chemical processes within the brain. Instead of a single piece of paper to file away, it’s more like your brain has to organize and decide what to keep from a box filled with a book, a video file, an audio recording, a bottle of perfume, a pair of pants, and a string of Christmas lights. When you first get this box of stuff, that’s the most likely time that you’ll just throw it all away right then and there. Not every short-term memory becomes a long-term memory. But once you’ve had the chance to organize it and put those things away though, most of those memories are probably sticking around for good. That’s called consolidation, and once a memory has moved through the hippocampus and amygdala and been stored in the neocortex it tends to stay put. Unlike a piece of paper that fades over time, consolidated memories are the things from the box that your brain keeps; they might get a bit dusty on the shelf, but they’re stored as long term memories that you can recollect when needed.
The hippocampus, which is the part of your brain that stores and processes “episodic” memories, is right next to the amygdala which stores and processes “emotional” memories. Think of episodic memories as the who, what, when, and where of what happened, and emotional memories of the why and how it felt parts of an experience. Usually these are processed together and stored in a way where they can be easily cross-referenced– for example, hearing an old song may prompt you to recollect your seventh grade dance and how you felt slow dancing with your first crush. You likely didn’t store every detail of the entire gymnasium, but you might remember that you were wearing red (episodic memory) and felt butterflies in your stomach when your crush touched your hand (emotional memory).
Trauma is like a tornado ripping through the storage centre of your brain. Instead of an orderly process of sorting through each box of incoming information, pieces from different boxes get mixed together, some boxes get mis-labeled, and a lot of stuff that would usually be processed just gets blown away in the storm before it even gets into the storage room. The reason for this is that the amygdala, in addition to being the centre of emotional processing in your brain, is also your alarm centre. During a traumatic experience, the amygdala sounds the alarm to initiate a series of chemical reactions in your brain and body in order to help you survive. These survival reactions are commonly known as fight, flight, freeze, and fawn.
When your body is experiencing those trauma responses, all of your energy is directed towards the areas of your brain that are key for survival and away from the areas of your brain that are not deemed necessary for immediate survival– the latter of which includes short term memory storage. The experience of trauma causes gaps in your episodic memory; areas of shelves in your mental memory museum that are simply blank. A lot of information that would usually be stored and processed is totally lost, and other pieces of information are misplaced, mislabeled, or otherwise buried. That’s why it can be so difficult for survivors to remember exactly what happened in what order, and why they may start recalling more details of the event months or even years later. This is called dissociative amnesia, and it serves a protective function by keeping traumatic memories suppressed until an individual is psychologically ready to process them. Different therapy modalities may help someone sort through their memories and sometimes missing bits can be found, processed, and accurately labeled. But there are limits to that, and often a part of therapy is making peace with the gaps that remain.
People are capable of processing and healing from trauma without having to actively remember every bit of the experience, and that’s a good thing. But when it comes to the legal system, this entirely normal and well-studied phenomena of trauma responses and memory gaps is not only ignored, but frequently weaponized against survivors. Come back for part 2!
