Memory and Trauma

Traumatic events are encoded differently than our day-to-day life experiences which makes recalling and narrating the traumatic events different than recalling routine events. Before one can fully understand how trauma impacts memory it’s essential to understand how the hippocampus and amygdala impact our memories. The hippocampus puts events in chronological order and transfers it into a long-term episodic memory. The amygdala takes experiences involving threats and anger and turns it into an implicit memory that unconsciously affects thoughts and behaviors. The memories then become associated with a threat and anger so that we can quickly associate the event with future situations that appear threatening or stressful. In short, the amygdala creates an instant response to perceived danger.

Because stress and fear increasingly activate the amygdala, it reinforces traumatic memories while simultaneously impairing how the hippocampus functions. Individuals who have experienced trauma can have memory traces, or fragments, meaning the memories are not fully integrated into the hippocampus properly. Additionally, sensory information such as smells, sounds, or images that occurred during the traumatic event become linked to physiological fear symptoms such as shortness of breath, sweating, and rapid heart beat. 

For many, memories of a traumatic event are only recalled in fragments due to the victim's hippocampus not being able to encode the memory in a complete and chronological order. However, some aspects of a traumatic event are better remembered due to the adrenal glands releasing adrenaline which helps to encode memories to the hippocampus more intensely. “Flashbulb memories” are the result of a burst of adrenaline that enhances the memory of the trauma that in return strengthens memory pathways. The brain encodes what we are paying attention to and during a traumatic experience the brain focuses on what is essential to survival without focusing on other details. Because of this, it is unrealistic and irrational to expect victims to recall every aspect of the traumatic event from start to finish. 

Source: Department of Justice Canada