BEHAVIORAL AND NEURAL CORRELATES OF CONTEXT-DEPENDENT FEAR MEMORY PROCESSING IN MARMOSETS (CALLITHRIX JACCHUS)

Fear is supported by evolutionarily conserved neural systems that detect threats and guide defensive responses. Intense fear can induce long-lasting memories, expressed as persistent avoidance and hypervigilance. While adaptive in the presence of real danger, the persistence of these responses in safe contexts becomes maladaptive, contributing to phobias and anxiety disorders. Decades of work in rodents have advanced our understanding of the neurobiology of fear memory; however, the neural mechanisms underlying fear expression in primates remain poorly understood. To address this gap, we established a conditioned place avoidance (CPA) task in marmosets. During habituation, the animals freely explored a chamber divided into three compartments with distinct spatial cues, allowing the identification of individual baseline preferences. On the following day, animals were reintroduced to the chamber and an ethologically aversive unconditioned stimulus was presented in the preferred compartment. During this session, animals displayed fear-related behaviors, including escape responses, avoidance, staring, and increased visual scanning. When re-exposed to the chamber 24 h later in the absence of the aversive stimulus, animals continued to express high levels of these defensive behaviors, suggesting the expression of a contextual fear memory. In addition, we performed electrophysiological recordings during habituation, training and test sessions, and found that threat processing modulates hippocampal oscillatory dynamics. Together, these findings suggest that the hippocampus contributes to online threat evaluation and provide a translational framework for investigating the neural mechanisms underlying fear memory in non-human primates.