To form proper memories, a few steps must be followed.

Firstly, the event must be experienced. The sheer imagination of things that aren’t really true might represent psychosis. That’s a whole other matter.

Secondly, a memory must be created.

Thirdly, the memory must be consolidated. That is, placed into long-term storage in an organised way. In other words, the internal librarian of your brain grabs the recollection and shoves it into a mental shelf with some kind of labelling and retrieval system. That way, you can access it again when needed, providing you don’t have any overdue fines. That could be a metaphor for brain injury or anything that disrupting usual functioning.

In PTSD, the consolidation phase is messed up. Because the memory isn’t stored away properly, it involuntarily, inconveniently and semi-randomly replays. And since it’s not actually linked to a shelf place, it’s experienced in fragments that appear to be current. This explains the re-experiencing phenomenon.

In case of traumatic memory as in PTSD, the process of memory consolidation seems to fail. The traumatic memory trace stays primarily located in subcortical and primary perceptual areas, leaving it tightly coupled to its autonomic and perceptual markers, and lacking the appropriate integration in autobiographical, cortical memory networks. Exposure to a trauma trigger subsequently results in a solely involuntarily retrieved memory trace (intrusion), that is very hard to verbalize, often fragmented in time, and consisting for the most part of primary sensory information (images, smell, sounds) that is linked to physiological fear symptoms (Brewin, 2011). Due to the lack of autobiographical context, the memory is relived as happening in the present. Thus a failure to properly consolidate and thus emotionally depotentiate potentially traumatic memories may form the neural basis of key PTSD symptoms like unwanted memories, intrusive flashbacks, nightmares, hyperarousal, and dissociation. Reduction of PTSD symptoms is accomplished by successful transfer to pre-existent, cortical memory circuits.

This might explain why journalling is thought to be so helpful for processing emotional trauma. The explicit step-through of event recollection places it in the realm of a more logical part of the brain, for a grounding effect. Elaborating on the details of the event helps give it labels and keywords, allowing it to ultimately earn a place of belonging on the memory shelf.

Bibliography

1. van Marle H. (2015). PTSD as a memory disorder. European Journal of Psychotraumatology, 6, 10.3402/ejpt.v6.27633. https://doi.org/10.3402/ejpt.v6.27633