Impact of Posttraumatic Stress Disorder on the Behavioral and Multivariate Neural Correlates of Contextual Fear Learning.

BACKGROUND

Posttraumatic stress disorder (PTSD) is linked to impairments in fear learning, particularly context and safety cue discrimination. However, it remains unclear whether alterations in distinguishing threat and safety stem from trauma exposure itself or from anxiety-related pathology more generally. In this study, we used multiple control groups to disentangle the impact of PTSD on behavioral and neural indices of fear learning.

METHODS

Four groups of participants were recruited: PTSD related to interpersonal violence (n = 21), trauma-exposed control (n = 46), anxiety-control (n = 19), and healthy control (n = 34) groups. Participants completed a contextual fear conditioning task while undergoing functional magnetic resonance imaging. Multivariate pattern analysis was used to decode the anticipatory neural representation of the unconditioned stimulus (i.e., electric shock) when participants were presented with conditioned stimuli (CS).

RESULTS

Behaviorally, participants with PTSD showed poorer discrimination between high- and low-threat CS in trial-by-trial shock predictions compared with all control groups, with a convergent pattern in shock likelihood estimates. Neural shock reinstatement in the salience network discriminated between high- and low-threat stimuli to a greater extent in the healthy control group compared with the PTSD group. Shock representations in the medial prefrontal cortex and inferior frontal networks were more strongly coupled with shock likelihood estimates among healthy control and anxiety control groups, respectively, compared with the PTSD group.

CONCLUSIONS

PTSD is uniquely associated with poorer threat discrimination during fear learning. Neural networks that encode differential threat expectation for CS among healthy control participants do not discriminate threat magnitude among participants with PTSD.