Reframing PTSD for computational psychiatry with the active inference framework

Abstract

Introduction: Recent advances in research on stress and, respectively, on disorders of perception, learning, and behaviour speak to a promising synthesis of current insights from (i) neurobiology, cognitive neuroscience and psychology of stress and post-traumatic stress disorder (PTSD), and (ii) computational psychiatry approaches to pathophysiology (e.g. of schizophrenia and autism).Methods: Specifically, we apply this synthesis to PTSD. The framework of active inference offers an embodied and embedded lens through which to understand neuronal mechanisms, structures, and processes of cognitive function and dysfunction. In turn, this offers an explanatory model of how healthy mental functioning can go awry due to psychopathological conditions that impair inference about our environment and our bodies. In this context, auditory phenomena—known to be especially relevant to studies of PTSD and schizophrenia—and traditional models of auditory function can be viewed from an evolutionary perspective based on active inference.Results: We assess and contextualise a range of evidence on audition, stress, psychosis, and PTSD, and bring some existing partial models of PTSD into multilevel alignment.Conclusions: The novel perspective on PTSD we present aims to serve as a basis for new experimental designs and therapeutic interventions that integrate fundamentally biological, cognitive, behavioural, and environmental factors.

Trauma or Drama: A Predictive Processing Perspective on the Continuum of Stress

“…As a result, the negative affect is mitigated during a traumatic event, which may be adaptive as a peri-traumatic response but becomes maladaptive long-term, making dissociation one of PTSD symptoms (DSM-5). On the other hand, the post-traumatic model of the world is believed to rely on hyper-precise predictions of threat that do not require sensory confirmation for triggering a metabolic 'fight or flight' response (Linson & Friston 2019). We think that the hypothesized insensitivity (under-weighting) to PE is an essential property of traumatic stress response and will expound it further below.…”

“…PPF has recently been applied to trauma (Wilkinson, Dodgson, & Meares 2017, Linson & Friston 2019, where different manifestations of PTSD are regarded as a trauma-induced malfunction of the brain's generative model. For example, dissociation is thought to result from the fragmentation of the generative model, where the model of the self is disconnected from the model of the traumatic event.…”

“…Neither impaired self-regulation nor dissociation has been noted as core features of depression, moreover, the adaptive value of depressive stress response including rumination has been highlighted by some researchers (Andrews & Thompson 2009, Nesse 2000, Gilbert 2006). Linson & Friston (2019) suggest that a traumatized generative model is characterized by decoupling of top-down priors from the bottom-up sensory information processing, which makes the organism react to the sensory cues according to its 'threat' priors. This decoupling is seen as the mechanism of impaired reality testing observed in such PTSD symptoms as hypervigilance and increased startle response (to auditory stimuli, in particular) and implies selective underweighting of ePEs.…”

“…The evidence that trauma and PTSD, in particular, are associated with false inference, where hyper-precise threat priors skew the perception (sometimes to the point of flashback and hallucination) has been reviewed before (Wilkinson, Dodgson, & Meares 2017). Likewise, false interoceptive inference in PTSD has been extensively discussed (Linson & Friston 2019). Here, we want to highlight perhaps the most direct indications of impaired predictive processing in trauma.…”

More Than Words Can Say: A Multi-Disciplinary Consideration of the Psychotherapeutic Evaluation and Treatment of Alexithymia

“…As beliefs, or priors, are updated, emotions are consequently generated (49,69). Further iterations of interoceptive inference of emotional state will ultimately lead to emotional awareness (70).…”