[Animal models of trauma and post-traumatic stress disorder]

Initially believed to be specific to humans emerging from life-threatening events, Post-traumatic stress disorder (PTSD) has been found to occur in wild animals and can also be experimentally induced in laboratory rodents. This article aims to highlight and discuss the evolution and relevance of animal models in PTSD research. Studies by LeDoux, Davis, and McGaugh have made significant contributions to our understanding of PTSD. By focusing on fear responses in rodents and aversive Pavlovian conditioning, they suggested that PTSD could result from excessively efficient aversive learning processes, with a significant role played by amygdala. However, numerous studies have shown that this explanation fails to account for the complexity of processes involved in PTSD. Current hypotheses focus on deficits in extinction retention, perception of safety signals, or emotional regulation. This review will specifically address the animal models that closely resemble human PTSD and explore reasons for their limited utilization, as a majority of animal studies continues to employ classical Pavlovian conditioning protocols. Furthermore, this review will present cutting-edge experimental studies that tackle previously challenging questions in animal research. Specifically, we will examine the relationship between respiration and the maintenance of fear states, offering a potential explanation for the efficacy of meditation and breath control techniques in emotion regulation. We will also shed light on recent findings on decoding neural activity related to internal representations in animals, thus enabling now the exploration of rumination, a characteristic symptom of PTSD previously inaccessible to animal studies.