Memories don’t live just in your head, but in your body too.
Memory is a fascinating and complex topic. We all know that when it comes to memory our brains are not infallible record-keepers that perfectly capture facts, neatly filing them away until we decide to review them later on. Far from it.
We know that memory is a bit more subjective and imperfect than that. But how exactly does it work? And how is it possible for our memories to impact our physical health?
To understand memory, it’s important to know that there are two different ways our brains encode memories. These two types of memory are called explicit memory and implicit memory.
Explicit memory is the one people often think of when they’re talking about memory. Explicit memory is the type of memory you use when recalling facts, like remembering state capitals or what you ate for dinner last night. When you recall an event and it plays like a movie in your mind’s eye – that’s explicit memory. And it’s predominantly governed by part of the brain called the hippocampus.
Then there’s the type of memory you’re not as consciously aware of – it’s called implicit memory. Implicit memory is often experienced as a memory stored in our body, like the “muscle memory” of riding a bike that remains in your body even if it has been years since you last rode a bike. Implict memory is mediated by the amygdala (the hippocampus’ neighbor), which is a part of the brain intimately involved in processing emotions related to our survival (like fear).
Here’s another example of implicit memory: say you were in a car accident years ago where you heard screeching tires and the sound of a car horn, which were followed by pain and injury. Now when you hear the screech of tires or a car horn in traffic you feel your shoulders tense, your limbs brace, and you gasp hold your breath – the tensing, bracing, and breath-holding are the physical body memories left over from the accident (even if you’re not consciously recalling the details of the accident in your mind). This is implicit memory at work.
The amygdala doesn’t have a nuanced sense of time; it doesn’t distinguish between past and present when an implicit memory is activated. The amygdala signals in real-time, making the body memories feel just as real now as they were when the original incident occurred.
This is the principle at the core of understanding Post-Traumatic Stress Disorder (PTSD). This is why a veteran with PTSD from active combat will jump and feel a surge of adrenaline at the sound of fireworks exploding on the Fourth of July. Or why an assault-survivor will feel their body tense and prepare to run when they sense someone who looks/sounds/smells like their attacker. These stimuli are triggering the implicit memory encoded in the amygdala and producing a real-time physical response. These body memories come complete with changes in muscle activation, breathing, heart rate, sweating, stress hormones and more.
This is how memories of past experiences, encoded in our bodies, can have a very real impact on your physical body in the present. And it is possible to experience the physical expression of an implicit memory without having conscious awareness (explicit memory) of where it came from.
Of course, not all implicit memories are negative – some are positive and pleasurable. But if your body is holding implicit memories of stressful/dangerous experiences it can keep your body in a chronic state of stress and immune system activation and you may experience symptoms like: muscle tension (especially in the neck/shoulders, hips, or jaw), shallow breathing/trouble getting a full easy breath, trouble sleeping, digestive problems, weight gain, and other chronic health conditions.
If this sounds like you, don’t worry, there is some good news: it is possible to change these body-memories so that the triggering stimulus no longer produces the unwanted physical reaction. A great place to start is by finding a therapist who understands the mind-body connection or uses a trauma-informed approach (like Internal Family Systems or EMDR). Another great resource is the book Your Resonant Self by Sarah Peyton where you can learn more about body memories and the inner-workings of your brain and learn techniques to create ease in your body and mind.