Thesis defense Linda de Voogd (Donders series 283)

11 May 2017

Promotor: prof. dr. G. Fernández, copromotor: dr. E. Hermans

Do you remember what you did last summer? On the formation and alteration of memories for stressful experiences

While it can be difficult to remember what you had for dinner last Tuesday, emotional events that happened years ago can often easily be retrieved from your memory. Some memories can be so strong they can even develop into traumatic memories. I found that the brain replays emotional events after the occurrence of such an event. This mechanism ensures that significant and emotional events from our lives are well remembered. However, it could also be that via this mechanism traumatic events, such as war situations, are hard to forget and can even lead to the development of posttraumatic stress disorder (PTSD).

I also found these memories can be forgotten by making simple eye movements. When making eye movements, activity in a brain region called the amygdala is suppressed. This region is involved in forming memories for stressful experiences. It was shown before that invasive pharmacological manipulations can suppress activity in the amygdala, but now we know the same can be accomplished by making simple eye movements. The eye movements are already used in a therapy called Eye movement desensitization and reprocessing (EMDR). Therapists saw this therapy was effective, but did not know why.

The results of this thesis give insight into the neurobiological mechanism underlying the strong retention of traumatic memories and offer new perspectives to treat disorders such as PTSD for example with non-invasive manipulations such as eye movements.