Autobiographical recall of a stressful negative event in veterans with PTSD

Integrating and fragmenting memories under stress and alcohol

Stress can powerfully influence the way we form memories, particularly the extent to which they are integrated or situated within an underlying spatiotemporal and broader knowledge architecture. These different representations in turn have significant consequences for the way we use these memories to guide later behavior. Puzzlingly, although stress has historically been argued to promote fragmentation, leading to disjoint memory representations, more recent work suggests that stress can also facilitate memory binding and integration. Understanding the circumstances under which stress fosters integration will be key to resolving this discrepancy and unpacking the mechanisms by which stress can shape later behavior. Here, we examine memory integration at multiple levels: linking together the content of an individual experience, threading associations between related but distinct events, and binding an experience into a pre-existing schema or sense of causal structure. We discuss neural and cognitive mechanisms underlying each form of integration as well as findings regarding how stress, aversive learning, and negative affect can modulate each. In this analysis, we uncover that stress can indeed promote each level of integration. We also show how memory integration may apply to understanding effects of alcohol, highlighting extant clinical and preclinical findings and opportunities for further investigation. Finally, we consider the implications of integration and fragmentation for later memory-guided behavior, and the importance of understanding which type of memory representation is potentiated in order to design appropriate interventions.

Imagining emotional future events in PTSD: clinical and neurocognitive correlates

Emotional future thinking serves important functions related to goal pursuit and emotion regulation but has been scantly studied in posttraumatic stress disorder (PTSD). The current study sought to characterize emotional future thinking in PTSD and to identify clinical and neurocognitive profiles associated with potential alterations in the level of detail in narratives of imagined future events. Fifty-eight, trauma-exposed, war-zone veterans, who were classified into current PTSD, past PTSD, and no-PTSD groups, were asked to vividly imagine future events in response to positive and negative cue words occurring in the near and distant future. These narratives were scored for internal (i.e., pertaining to the main event) and external (i.e., tangential to the main event) details. Participants also performed neurocognitive tasks of generative ability, working memory, and relational verbal memory. Linear mixed modeling revealed that the current and past PTSD groups generated fewer internal details than the no-PTSD group across positive and negative cue words and across temporal proximity. Partial least squares analysis revealed that symptom severity for all PTSD clusters was inversely associated with production of internal details, albeit with the association relatively weaker for intrusion symptoms. Among the neurocognitive tasks, only relational verbal memory was associated with production of internal details. These findings suggest, as predicted, that functional avoidance may underlie reduced detail generation but also point to potential additional mechanisms to be further investigated. That future event simulation remains overgeneral even when PTSD symptoms abate highlights the importance of addressing alterations in future thinking in this population.