psychology | trauma | memory mechanisms

What Is Special About Trauma Memories?

Exploring the mechanisms of encoding and retrieving trauma memories

Through evolution, the brain is hardwired to remember danger and respond accordingly. Memory pathways create shortcuts in the brain, in a way that makes activation and response almost instant. Due to the brain’s perception of the self-being in danger, it stores and retrieves traumatic memories differently than regular memories.

The picture above shows the activation (green dots) of cells in the brain’s auditory cortex when a tone associated with danger is heard. The red dots are the so-called “tracers” that arrive instantly from the amygdala to check out what’s happening, as the auditory cell “remembers” the danger.

The amygdala is part of the limbic system, which is a primitive part of our brain. The amygdala is responsible for our emotional responses, and emotion-related memories. In the picture labeled as “the path of fear” by the scientists who captured it, we can see how the cells that receive the information in the brain from what we hear from an outside source activate because of the association with danger. Simultaneously, the amygdala releases its tracers and confirms that the danger is indeed present. Those tracers will then pass on the information to the amygdala, which will in turn react to make us feel an emotion — in that case, fear.

In a previous article, I discussed how memories can be distorted. Research has shown that traumatic memories can be distorted right when they are being encoded (stored) in the brain (source). In a study conducted with people who have survived a terrorist attack, it was found that those who did not get symptoms of PTSD (post-traumatic stress disorder) after the attack were more successful in suppressing the trauma-related memories, and had an overall greater emotional resilience (source).

While it was believed that trauma memories are inherently fragmented and disorganized, it appears that their fragmentation and disorganization occur after repeated inappropriate retrieval (source). In other words, recalling repeatedly a traumatic memory is not the same thing as safely processing it.

Moreover, other research has shown that people with anxiety have a harder time with face recognition, especially when their brain perceives that it’s being under stress (source). This is a crucial finding with regards to memory encoding and retrieval in trauma because, as that study showed, people who are more prone to anxiety have a hyper-functioning perception of their surroundings (i.e. they are being on alert) at the expense of a more accurate memory encoding of faces.

This means that a trauma memory in people with anxiety is more likely to include other spatial elements. They are therefore harder to extinguish because the triggers automatically multiply, as they encompass everything in the person’s spatial awareness (e.g. sounds, smells, other sensory stimuli, emotions, etc.).

Time perception is one more factor that affects the encoding of trauma memories. I have previously explored how our mental states affect the way we perceive time. The slowing down or speeding up of time while trauma is occurring is also connected to the phenomenon of dissociation, which is when the person feels disconnected from their surroundings. The way our brain perceives the passing of time as the trauma memory is being encoded is one more important thing to know in order to retrieve and process the trauma memory correctly (source).

One more important factor for encoding and retrieving stored trauma memories is our imagination. As discussed in an older article, some people have a hyperactive imagination (hyperphantasia), while other people can form little to no mental imagery (aphantasia). With regards to encoding trauma memories, people on the aphantasia spectrum are less likely to have PTSD symptoms that include the intrusive recall of the traumatic memory because they can’t visualize the memory (source). However, they can remember their trauma and talk about it (source).

This is important to keep in mind for other cases as well. Just because someone can’t recall all aspects of their trauma or can’t describe their trauma-related imagery, this does not lessen the degree of their suffering and it’s not evidence that the trauma wasn’t real.

Summary

• Trauma-related memories differ in the way in which they are encoded as the trauma occurs.
• The characteristics of the person can influence how the memory will be encoded due to the way time is perceived, as well as due to the way the surrounding imagery is encoded or not.
• The retrieval of the traumatic memories plays a role in how those memories will be altered over time (e.g. become more severe or influence other memories).

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