Moral injury (MI) is associated with severe blame-related emotion and the development of psychopathology including posttraumatic stress disorder (PTSD). Little is known about how MI events are neurally processed when PTSD is comorbid, limiting the development of tailored interventions. Thus, this thesis sought to provide a novel, multi-method examination of the biological underpinnings of moral injury and relevant behavioural correlates. Study one provides the first investigation into the neural activation patterns elicited during MI event recall in military members and public safety personnel with PTSD, relative to MI-exposed civilian controls. In PTSD, emotional processing is challenged by heightened sensory information. Here, we provide evidence of heightened viscerosensory information processing (i.e. internal gnawing or gastrointestinal constriction related to blame-based emotion) during MI event recall, which appears to exert a strong influence over cortical regions facilitating moral cognitive processes including emotion regulation, autobiographical memory integration, and social cognition. Overwhelming visceral sensations can elicit defensive behaviour including tonic immobility (TI), a defensive response that facilitates viscerosensory dampening. Interestingly, more severe negative alterations in cognition and mood were associated with viscerosensory dampening in our PTSD group, pointing towards a compensatory pattern of emotional numbing. Studies two and three explore two posttraumatic symptoms consistent with emotional numbing: alexithymia and posttraumatic TI. In study two, we explore posttraumatic TI as a survival-based dissociative response and test a new measure of posttraumatic TI. In study three, we provide evidence that alexithymia is associated with an altered (muted) pattern of emotion-specific bodily sensation. This thesis provides a framework for embodied MI event processing in PTSD and highlights the importance of assessing the somatic experience of MI and screening for TI responses and emotional numbing as part of PTSD symptomatology. The evidence presented here suggests sensorimotor-based approaches and bottom-up regulatory strategies may be useful adjuncts to MI event processing. / Dissertation / Doctor of Philosophy (PhD) / Moral injury (MI) is a psychosocial-spiritual injury that can occur when deeply held values are violated either by oneself or a trusted other; it produces considerable pain and social alienation. MI has been linked to suicide and the development of posttraumatic stress disorder (PTSD), a mental health condition associated with distressing symptoms and reduced functioning in important areas of life, including social relationships. This thesis focuses on how MI events are processed by military members and public safety personnel, who are both at risk for MI and PTSD. We investigate how shame is experienced in the brain and body, and explore how intensified visceral sensations may become overwhelming (e.g., pit in stomach, vomiting) prompting emotional numbing or difficulties remaining embodied in the present moment (e.g., zoning out, freezing up). By understanding MI event processing when PTSD is present, we hope to gain insight into more effective treatments for these individuals.