Developmental Differences in a Hippocampal-Cingulate Pathway Involved in Learned Safety Following Interpersonal Trauma Exposure.

Abstract

Nearly 65% of youth experience trauma, and up to one-third of youth with trauma exposure face profound mental health sequelae. There remains a need to elucidate factors that contribute to psychopathology following trauma exposure and optimize interventions for youth who do not benefit sufficiently from existing treatments. Here, we probe safety signal learning (SSL), which is a mechanism of fear reduction that leverages learned safety to inhibit fear in the presence of threat-associated stimuli and has been shown to attenuate fear via a hippocampal-cingulate--specifically, dorsal anterior cingulate cortex (dACC)--pathway. The present study used behavioral and task-based functional magnetic resonance imaging data to examine age-related associations between interpersonal trauma exposure and the behavioral and neural correlates (i.e., activation and functional connectivity) of SSL in a group of 102 youth (ages 9-19; 46 female, 56 male) with (n=52) and without (n=50) interpersonal trauma exposure. Primary analyses examined anterior hippocampal activation and anterior hippocampus-dACC functional connectivity. Exploratory analyses examined centromedial (CMA) and laterobasal (LBA) amygdala activation and anterior hippocampal, CMA, and LBA functional connectivity with additional anterior cingulate subregions (i.e., subgenual anterior cingulate cortex [sgACC] and rostral anterior cingulate cortex [rosACC]). Both youth with and without interpersonal trauma exposure successfully learned conditioned safety, which was determined using self-report of contingency awareness. Youth with interpersonal trauma exposure-relative to youth in the comparison group-exhibited age-specific patterns of lower hippocampal activation (F(2,96)=3.75, pFDR=.049, ηp2=.072), and, in exploratory analyses, showed heightened centromedial amygdala activation (F(1,96)=5.37, pFDR=.046, ηp2=.053) and an age-related decrease in hippocampal-sgACC functional connectivity during SSL (F(1,94)=10.68, pFDR=.015, ηp2=.102). We also show that hippocampal-sgACC functional connectivity mediated the association between interpersonal trauma exposure and PTSD symptoms in an age-specific manner in the overall sample. Together, these findings suggest that although age- and trauma-specific differences in the neural correlates of SSL may relate to the development of psychopathology, youth with interpersonal trauma exposure demonstrate successful learning of conditioned safety over time.