When people rest immediately after a traumatic experience, they have less intrusive memories of the experience later on.

That is the conclusion of a group of neuroscientists from London. In their study, they played “traumatic” videos for two groups of healthy subjects. These were realistic 30-second videos showing people who were seriously injured or in danger of dying. Immediately after playing these videos, one group was given 10 minutes to calmly recover, while the other group had to perform a short memory task with numbers. The test subjects who were allowed to let their thoughts wander had less intrusive memories of their viewing experience during the following week.

Posttraumatic stress disorder

Intrusive memories are a common phenomenon in people who have experienced trauma, such as those with post-traumatic stress disorder (PTSD). People with PTSD are left with serious psychological problems from their trauma. For example, they can become very anxious when memories of their trauma surface.

Such memories can intrude on someone with PTSD, without the person having conscious control over it. However, a trigger often takes place before the memory of the trauma is activated. Wandering thoughts, certain sounds or locations can all remind the person of the trauma.

Controllable memory

Although the otherwise healthy subjects in the study did not develop PTSD after watching the videos, they did experience intrusive memories of the images afterwards. They wrote them down in a diary. In particular the test subjects who couldn’t rest after seeing the videos recorded many such memories in their diary.

After a week of writing, the subjects returned to the laboratory one last time for a memory test. Using this test, the researchers wanted to know whether the controllable (or “conscious”) memory differed between the two groups.

To test this, the subjects were briefly shown images that previously appeared in the traumatic films, alternated with new images. They had to indicate which of the images they recognized from the videos, and which were new. It turned out that the controllable memory of both groups did not differ and remained intact.

Contextualization

Memories of traumatic events or experiences are stored in the brain. Normally, in “healthy” cases, memories are put into context.

In people with PTSD, the memory can become disconnected from the context. Benno Roozendaal, professor of behavioral neuroscience at Radboud University in Nijmegen, is researching the role of memory in the development of PTSD. Roozendaal explains what reduced contextualization of memories means for the development of PTSD: “I often use the example of a combat helicopter in Afghanistan. A war veteran is startled by the sound of a helicopter because of his war experiences. It is good if he is startled by helicopter noises in Afghanistan, but not if he is startled by helicopters when he is back in the Netherlands. ”

According to the researchers’ interpretation of the study, the rest period helps to contextualize (or process) the traumatic images. The hippocampus, a brain area located on the inside of the temporal lobe, plays a major role in such contextualization. Because the images are put in the right context, the emergence of intrusive memories later on is attenuated.

The researchers’ hypothesis of ​​contextualization of images by the hippocampus is interesting according to Roozendaal: “Improving the function of the hippocampus seems like a good idea. The question is how you can do that in a simple way. ” Unfortunately, the researchers did not measure the activity of the subjects’ hippocampus during the experiment. Roozendaal thinks this is a missed opportunity: “I really would have liked to see that brain activity. It is now purely a behavioral experiment. ”

Although the findings are promising, the treatment of people with PTSD still seems a long way off. A real trauma is very different from a couple of videos, says Roozendaal. “If someone experiences a severe trauma, it is difficult to tell this person to just lie down for 10 minutes and think about it.”

The study results were published in the scientific journal Scientific Reports.

This is a translation of the article published here.