Those with posttraumatic stress disorder frequently experience unwanted memories of their traumas, even when making explicit efforts to avoid them, while healthy individuals can suppress those memories

Behavioral and neural correlates of memory suppression in PTSD. Danielle R. Sullivan et al. Journal of Psychiatric Research, Volume 112, May 2019, Pages 30-37. https://doi.org/10.1016/j.jpsychires.2019.02.015

Highlights
•    Trauma exposure is associated with behavioral difficulties in memory suppression.
•    Right middle frontal gyrus activity is reduced during memory suppression after trauma exposure.
•    Trait suppression is negatively correlated with reduced right middle frontal gyrus activity.

Abstract: Previous work has shown that healthy individuals can actively suppress emotional memories through recruitment of the lateral prefrontal cortex. By contrast, individuals with posttraumatic stress disorder (PTSD) frequently experience unwanted memories of their traumatic experiences, even when making explicit efforts to avoid them. However, little is known regarding the behavioral and neural effects of memory suppression among individuals with PTSD. We examined memory suppression associated with PTSD using the Think-No-Think paradigm in an event-related functional magnetic resonance imaging (fMRI) study. We studied three groups: PTSD (n = 16), trauma exposure without PTSD (n = 19), and controls (i.e., no trauma exposure or PTSD; n = 13). There was a main effect of memory suppression such that participants remembered fewer face-picture pairs during the suppress condition than the remember condition. However, trauma-exposed participants (regardless of PTSD status) were less likely to successfully suppress memory than non-trauma-exposed controls. Neuroimaging data revealed that trauma-exposed individuals showed reduced activation in the right middle frontal gyrus during memory suppression. These results suggest that trauma exposure is associated with neural and behavioral disruptions in memory suppression and point to the possibility that difficulty in active suppression of memories may be just one of several likely factors contributing to the development of PTSD.