Pre-trauma cognitive traits predict fear generalization and associated prefrontal functioning in a longitudinal rodent model

TL;DR

This study shows that pre-trauma learning abilities predict fear responses in rats, with brain activity and gene expression in the prefrontal cortex playing a key role in PTSD-like symptoms.

Contribution

The study identifies pre-trauma operant learning as a novel predictor of PTSD-like fear generalization and reveals prefrontal interneurons as potential therapeutic targets.

Findings

Reduced pre-trauma operant learning strongly predicts excessive fear generalization after trauma.

Vulnerable rats show altered medial prefrontal cortex dynamics and less coordinated subregion activity.

Silencing prefrontal Crh expression reduces fear expression and enhances prefrontal cortex activation.

Abstract

Posttraumatic stress disorder (PTSD) is a chronic psychiatric condition that develops in susceptible individuals exposed to traumatic stress. Identifying predisposing risk factors and mechanisms presents a significant challenge for prevention and therapy development. Here, we aimed to identify behavioral predictors of excessive fear generalization - a core symptom of PTSD - and its neural correlates in rats using a longitudinal design. Prior to trauma, rats underwent extensive behavioral test batteries to assess their emotional and cognitive traits. They were then exposed to a single traumatic experience via inescapable footshocks. Twenty-eight days later, fear generalization was measured in a neutral/safe context, differentiating vulnerable (high freezing) and resilient (low freezing) subpopulations. Reduced pre-trauma operant learning performance emerged as the strongest predictor of excessive fear generalization. Neuronal activity mapping revealed altered medial prefrontal cortex (mPFC) dynamics in vulnerable animals, characterized by activity changes and less coordinated activity-coupling between subregions. Gene expression analysis and cell-specific activity labeling pointed to VIP/CRH+ interneurons as potential mediators of excessive fear. As a molecular intervention, silencing prefrontal Crh expression after fear memory consolidation markedly enhanced mPFC activation and reduced fear expression, supporting a regulatory role of this interneuron population in fear processing. As a behavioral intervention, post-trauma operant training facilitated the reduction of generalized fear and led to changes in plasticity-related gene expression in the mPFC, indicating overlapping neural circuits governing operant learning and fear regulation. These findings together highlight operant learning and mPFC network functions as vulnerability markers and mediators of excessive fear generalization, with implications for prevention and targeted therapy in PTSD.

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