How extreme fear shapes what we remember

Many of us will experience a significant trauma in our lives, says Lesley Evans Ogden. Yet could there be ways to avoid reliving the memories?

Published: 6^th February 2015

Source:  Lesley Evans Ogden, BBC News

Link: http://www.bbc.com/future/story/20150205-how-extreme-fear-shapes-the-mind

Science field: Health, brain, neuroscience and psychology

Summary

After boarding their flight in Canada, Margaret McKinnon and her husband were heading for Lisbon. It was when the Air Transat flight 236 was soaring over the mid-Atlantic when the crew announced they would be making an emergency landing and started to instruct passengers on how to put on their life jackets: the cabin depressurised and oxygen masks deployed. Finally they were lucky; the pilots had established contact with Lajes, a joint military-civilian air base in the Azores so that they could land. But for many the flight didn’t end there; the terrifying experience replayed vividly as memories and nightmares, in others words Post Traumatic Stress Disorder (PTSD).

The experience inspired McKinnon, now psychologist, to study what makes fearful experiences seem to become imprinted so deeply in our brains.

Fearful imprint:

The link between fear and memory has intrigued researchers and clinicians for decades. But few studies have looked at memory during the experience of trauma itself, especially for a single, shared event. So McKinnon decided to delve into the memories of her fellow passengers on Air Transat flight 236.

In the research they found that all passengers had vivid and enhanced recollections of the incident, supporting the idea that fear changes how the brain stores memories. In those that subsequently developed PTSD, “they showed a lot of recollection of extraneous details”. So if traumatic memories are more vivid, what’s going on inside our heads when they are ‘made’? There are multiple memory systems in the brain. We have physical and auditory memories, but we also have more specific “declarative” memory systems heavily involving the hippocampus.

But fear activates a different system: our body’s emergency control centre – the amygdala. The amygdala, a pair of almond-shaped structures on the left and right of the brain’s medial temporal lobe, is particularly involved in emotional memories like fear, but also in pleasurable memories. When a memory is particularly striking and unexpected, it activates this emotional memory system.

Flashbulb memories:

Elizabeth Phelps, a professor of psychology and neural science at New York University, was interested in people called “flashbulb memories” of 9/11 who are not individuals with PTSD.

In a large-scale detailed survey conducted first within a few weeks of 9/11, then one year, two years, and 10 years later, they found that “people were very confident that the details of their memory were correct”. Not the detail in terms of the fact that it happened, but where they were, who they were with, how they first heard about it, and what they did afterwards. However, personal recollections of the contextual details often actually changed with time.

“With highly traumatic events we think we have this incredibly accurate memory,” she says. The truth is, many of the details we think are accurate are not. “Emotion focuses your attention on a few details, at the expense of a lot of others.”

Total recall:

So can traumatic memories be manipulated, even removed? Based on an emerging understanding of the storage and retrieval of memory, we have windows of opportunity for altering the closure of fearful memories in the brain. Indeed, there is emerging evidence from rodent and human studies that drugs called beta-blockers can achieve a reduction in later PTSD symptoms if administered quickly.

Departure points:

As for McKinnon, she admits that despite her vividly traumatic experience, there are many details she can’t remember.

Glossary:

-          Newlywed: a recently married person

-          Odd: occasional, incidental, or random

-          Yelling: to shout, scream, cheer, or utter in a loud or piercing way

-          Brace: something that holds parts in place, such as a clamp

-          Lessen: to make or become less.

-       Beta-blocker: any of a class of drugs, such as propranolol, that inhibit the activity of the nerves that are stimulated by adrenaline; they therefore decrease the contraction and speed of the heart: used in the treatment of high blood pressure and angina pectoris.

-          Sharp: ending in an edge or point.

-        Chutes: an inclined channel or vertical passage down which water, parcels, coal, etc, may be dropped.

Review

This article shows the kind of problems caused by the Post Traumatic Stress Disorder (PTSD), a mental health condition that is triggered by a terrifying event - either experiencing it or witnessing it. Its symptoms may include flashbacks, nightmares and anxiety, as well as uncontrollable thoughts about the event. The experience of Margaret McKinnon changed her life, so she decided to study how fear affects people’s memories and the way they change the experience that they have lived. Post Traumatic Stress Disorder is usually common in Veterans of War.

Written by Alba Pazos