One of the key symptoms associated with post-traumatic stress disorder (PTSD) is memory of past traumas in the form of flashbacks.
In the immediate aftermath of a traumatic incident, the people who survive or witness the event tend to go about their daily lives in a kind of self-protective bubble. The brain mechanisms that might normally be expected to express shock, outrage or horror become numb.
This is a process related to our survival instinct. It allows us insulate ourselves from the direct effects of the trauma but it often resurfaces when the danger has passed. The National Institute of Mental Health points out that PTSD can happen to anyone at any age and the symptoms may start soon after the trauma, or even months or years later.
The Experience of Flashbacks
Flashbacks are often popularized in movies as a momentary reliving of the trauma. This is certainly part of the story, but the recognized features of flashbacks may or may not include memories of the sights and sounds of the trauma.
Sometimes the main features are a sense of claustrophobia, panic and helplessness, which may also occur in dreams. The feelings are intense, unpleasant and leave the sufferer feeling vulnerable and overwhelmed. They often question their own sanity because the sensations they experience are out of context with their everyday reality.
In a post for Psychology Today, Tom Bunn provides a vivid example of a Vietnam veteran who suddenly slammed on the brakes of his car, jumped out, and threw himself into a ditch. The cause of this dramatic behavior was the sound of a helicopter flying overhead.
This, Bunn points out, was an example of an explicit flashback, where the person lives a past trauma as though it was happening in the present. But flashbacks from childhood are different. Immature memories may not contain factual memories so much as** implicit** emotional states. In these situations, something in the present may trigger strong emotions, but not be the direct cause of them.
Traumatic Memories Lose Context
Normally when we lay down fresh memories, we not only store the event (e.g. meeting a new person) but also the context (e.g. at Sally’s 21st birthday party). These associations are stored in an area of the brain called the hippocampus. Once this information is stored, memories can then be retrieved in a variety of ways.
For example, a different party may remind us of that person. Conversely, meeting the person again may remind us of the party. Any associated senses, such as smells or sounds, can also aid in recalling the person, or the context, or both.
In the case of flashbacks something different seems to happen. Dr. James Bisby, of the Institute of Cognitive Neuroscience at University College London, says that bad experiences cause people to strongly recall negative content at the expense of the surrounding context. The study, published in Social, Cognitive and Affective Neuroscience, reveals the mechanisms that occur in the brain, which may help in our understanding of flashbacks.
Using an MRI scanner to monitor brain activity, 20 volunteers were shown pairs of pictures to remember. Some of these contained negative content such as badly injured people. Memory of the pictures was tested later. If the volunteers remembered the image they were asked to recall the neutral picture it was paired with. Volunteers were better able to recall negative pictures but much worse at remembering the pictures shown alongside, a feature confirmed by reduced activity in the hippocampus.
Vivid, distressing and intrusive images may occur due to strengthened memory for the negative aspects of trauma that are not associated with the context they occurred in.
PTSD TreatmenTSD is most commonly treated using cognitive behavioral therapy (CBT) with or without medication. Three main stages are used:
- An evaluation of negative thoughts about the trauma.
- Treating memories of the trauma, often by asking the person to relive the trauma mentally, and where possible revisiting the site of the trauma.
- Tackling behaviors that maintain PTSD, such as avoidance or attempting to suppress memories.
Unlike the normal storage of memories, those associated with trauma often leave the person with a poorly developed sense of meaning and context. That leads to constant and unwelcome intrusion, because what memories exist are disorganized. Appreciating the importance of rebuilding context may have important applications in therapy for the reduction and management of flashbacks.
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(1) University College London. "Why bad experiences are remembered out of context." ScienceDaily. ScienceDaily, 10 May 2016.