A traumatic memory can be nearly impossible to shake

Most of what you experience leaves no trace in your memory. Learning new information often requires a lot of effort and repetition — picture studying for a tough exam or mastering the tasks of a new job. It’s easy to forget what you’ve learned, and recalling details of the past can sometimes be challenging.
But some past experiences can keep haunting you for years. Life-threatening events — things like getting mugged or escaping from a fire — can be impossible to forget, even if you make every possible effort.
Bodies respond automatically to threatImagine facing extreme danger, such as being held at gunpoint. Right away, your heart rate increases. Your arteries constrict, directing more blood to your muscles, which tense up in preparation for a possible life-or-death struggle. Perspiration increases, to cool you down and improve gripping capability on palms and feet for added traction for escape. In some situations, when the threat is overwhelming, you may freeze and be unable to move.
Threat responses are often accompanied by a range of feelings. Senses may sharpen, contributing to amplified detection and response to threat. You may experience tingling or numbness in your limbs, shortness of breath, chest pain, feelings of weakness, fainting or dizziness. Your thoughts may be racing, or you may experience a lack of thoughts and feel detached from reality. Terror, panic, helplessness, lack of control or chaos may take over.
These reactions are automatic and cannot be stopped once they’re initiated, regardless of later feelings of guilt or shame about a lack of fight or flight.
Two routes in danger responseDefense responses are controlled by neural systems that human beings have inherited from our distant evolutionary ancestors.
One of the key players is the amygdala, a structure located deep in the medial temporal lobe, one on each side of the brain. It processes sensory threat information and sends outputs to other brain sites, such as the hypothalamus, which is responsible for the release of stress hormones, or brain stem areas, which control levels of alertness and automatic behaviors, including immobility or freezing.
The two-roads model explains how responses to a threat can be initiated even before you become consciously aware of it. The amygdala is interconnected with a network of brain areas, including the hippocampus, the prefrontal cortex and others, all of which process different aspects of defense behaviors. For example, you hear a loud, sharp bang and you momentarily freeze — this would be a low road-initiated response. You notice somebody with a gun, immediately scan your surroundings to locate a hiding spot and escape route — these actions wouldn’t be possible without the high road being involved.
After the memories are madeOne detail — the buzz of streetlights, a truck’s squealing tires — can trigger the memory of a traumatic accident.
Researchers believe traumatic memories are a conditioned threat response. For the survivor of a bike accident, the sight of a fast approaching truck resembling the one that crashed into them may cause the heart to race and skin to sweat. For the survivor of a sexual assault, the sight of the perpetrator or someone who looks similar may cause trembling, a feeling of hopelessness and an urge to hide, run away or fight. These responses are initiated regardless of whether they come with conscious recollections of trauma.
Memories are biological phenomena and so are dynamic. Exposure to cues that trigger the recall or retrieval of traumatic memories activates the neural systems that are storing the memories. This includes electrical activation of the neural circuits, as well as underlying intracellular processes.
There are clinical strategies to help people heal from emotional trauma. One critical factor is the sense of safety. Retrieval of traumatic memories under safe conditions when levels of stress are relatively low and under control enables the individual to update or reorganize the trauma experience. It’s possible to link the trauma to other experiences and diminish its destructive impact. Psychologists call this post-traumatic growth.
It is an ethical imperative to consider the circumstances under which traumatic memories are recalled, whether in the course of therapy, during police investigations, court hearings or public testimonies. Recalling trauma may be a part of the healing process or may lead to re-traumatization and continued detrimental effects from traumatic memories.
Source: University of Michigan Health Lab (uofmhealth.org), republished from The Conversation under a Creative Commons license.