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

Summary & key facts

In rats, poor performance on a pre-trauma learning task predicted who later showed excessive fear in a safe place after a single traumatic event. Twenty-eight days after the trauma, vulnerable rats froze more in a safe context and had changes in how the medial prefrontal cortex (mPFC) worked. The study points to a specific class of interneurons (VIP/CRH+) and to prefrontal Crh gene activity as possible biological players, and shows that both turning down Crh after the fear memory formed and doing operant training after trauma reduced generalized fear and changed mPFC activity and gene expression.

Key facts:

• Rats were tested on many behaviors before a single traumatic event and were re-tested 28 days after trauma to measure fear generalization in a safe context.
• Rats were divided into vulnerable (high freezing) and resilient (low freezing) groups based on freezing behavior in the safe context 28 days after trauma.
• Lower pre-trauma operant learning performance was the strongest behavioral predictor of later excessive fear generalization.
• Vulnerable rats showed altered medial prefrontal cortex (mPFC) dynamics, including changes in activity and weaker coordination (activity-coupling) between mPFC subregions.
• Gene expression and cell-specific labeling pointed to VIP/CRH+ interneurons as candidate mediators of excessive fear.
• Silencing Crh expression in the prefrontal cortex after fear memory consolidation increased mPFC activation and reduced fear expression.
• Providing operant training after trauma reduced generalized fear and changed expression of plasticity-related genes in the mPFC.

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.

Topics

Memory and Neural Mechanisms Posttraumatic Stress Disorder Research Stress Responses and Cortisol

Categories

Cognitive Neuroscience Life Sciences Neuroscience

Tags

Amygdala Aversive Stimulus Behavioral neuroscience Biological neural network Chronic stress Clinical psychology Cognition Cognitive psychology Cognitive vulnerability Developmental psychology Disinhibition Expression (computer science) Extinction (optical mineralogy) Fear conditioning Fear processing in the brain Fear-potentiated startle Generalization Interneuron Memory consolidation Nerve net Neural correlates of consciousness Neurocognitive Neuroplasticity Neuroscience Poison control Population Prefrontal cortex Psychology Rodent model Vulnerability (computing) Young adult

Conditions & symptoms

PTSD Anxiety or worry Difficulty focusing