Bodily distress and the 'predictive mind' - an osteopath's account

Embodied brains and the 'self'

Our 'invisible' bodies provide us with sensorial pleasures that arise from our activities of daily living, interactions with the environment and with others. Therefore, we live in a state of wellbeing when we do not need to think about our embodied organism (Arikha, 2019). However, physical or emotional pain affects the very foundation on which the sense of self rests, so our bodies become 'visible'! We may, therefore, realise that what we feel ourselves is a 'construction'. How we exist as embodied selves is a highly complex business involving the brain and body engaged in constant interaction (Arikha, 2019). Brains do more than merely filtering and making sense of their sensory input to using the body to sample and make sense of that input. Brains are therefore embodied - they talk to the environment through the body.

Complexity, bodily distress and the 'Bayesian Brain'

In cases of persistent pain, functional somatic syndromes and medically unexplained symptoms, physiological arousal prompt the individual to focus attention on their body. Misinterpreting the sensations as threatening then causes a further increase in arousal, creating a vicious cycle (Van den Bergh et al. 2017). Although the amplification model is intuitively appealing (Barsky et al., 1990), the evidence does not fully support the notion that functional somatic syndromes and medically unexplained symptoms result from dysregulated stress physiology, hypervigilance for bodily sensations, heightened interoceptive accuracy, or misinterpretations of physical sensations (Van den Bergh et al. 2017). Moreover, correlations between symptom reports and objective disease indicators are typically low to moderate, and emotional factors are central in symptom reporting (Van den Bergh et al. 2017).

Morrison and colleagues (2013) have argued that pain should not be viewed primarily as a sensation but as an action problem. Therefore, when a nociceptive signal travels up from the periphery via the spinal cord, it presents the brain with the question "what is to be done"? Research demonstrates that the nervous system is organised to anticipate potential pain and to adjust behaviour before the risk of tissue damage becomes critical. Regulatory processes occur dynamically at different levels and done in a Bayesian way; i.e., using previous experiences as they are represented in the brain as an estimate of the likelihood that a specific clinical condition applies (Morrison et al., 2013; Van Den Bergh et al., 2018). These views highlight the critical role that predictive processing models have in symptom generation. The brain has to produce an internal model that accounts for most of the information that is generated by somatic input (Van Den Bergh et al., 2018). Symptoms arise from unconscious inferential processes concerning the nature of interoceptive sensations while taking into account implicit beliefs and actions - this induces a sense of being real, regardless of the actual somatic input (Henningsen et al., 2018). Consequently, the relationship between symptoms and bodily dysfunction can be highly variable. It may be completely absent in conditions that are typically characterised by highly precise prior expectations and low precision prediction errors from somatic input (Henningsen et al., 2018).

The application of Predictive Processing theory to symptom generation and bodily distress is promising in bridging the gap between epistemology and mechanistic common-sense approaches. They eliminate the idea of a homunculus in the mind (that does the perceiving) and replacing it with statistical processes of predictions based on likelihood estimation (Van Den Bergh et al., 2018).

What is Predictive Processing?

What we perceive is always a balance between top-down knowledge-based prediction and bottom-up incoming sensory evidence. We see the world by deploying world-knowledge in the form of a generative model to attempt to construct the incoming sensory signal for itself, using stored probabilistic knowledge about the world (Clark, 2013). Brains predict and test their hypotheses against incoming sensory evidence rather than merely reacting to the world. Perception is an active process, with top-down mechanisms activated to make predictions about the upcoming bottom-up sensory signals (Friston, 2009). In Predictive Processing, the brain is a multi-level system that perceives the world by trying to predict its own sensory states. Each level attempts to predict the unfolding signal at the level below. Differences between the predictions and the current lower-level states are calculated, and only residual 'prediction errors' are sent forward and sideways to generate better forecasts and help drive learning (Clark, 2013).

Arguably, we live in a state of 'controlled hallucination' (Seth, 2013). Our brain's predictions constitute internal models of the body in the world, which are constructed via Bayesian inferences constrained by sensory inputs, from which all perceptions and actions emerge (Barrett et al. 2016).

How does this inform my work as an osteopath?

The relationship between the experience of physical symptoms and objective physical dysfunction is always contextualised, that is, influenced by specific factors within the historical person, the context, and their interaction. Therefore, the relationship between symptoms and physiological dysfunction may vary both within-person and within-situation (Van den Bergh et al. 2017) substantially. Arguably, we feel pain because we predict that we are in pain, based on an integration of sensory inputs, prior experience, and contextual cues (Ongaro and Kaptchuk, 2018).

From a Bayesian perspective, the medical ritual prompts the brain to interpret even small interoceptive changes in the body as the consequence of healing and to experience relief accordingly (Ongaro and Kaptchuk, 2018). Under precise predictions of incoming health, the brain can also arrive at symptom relief through processes of active inference (Ongaro and Kaptchuk, 2018). The brain may initiate healthful visceral sensations (e.g., relaxing stomach muscles) that conform to the hypothesis that one is returning to a "healthy body condition' —all this to fulfil the prediction and minimise error (Ongaro and Kaptchuk, 2018).

Osteopaths act on the body, and the body is how the brain perceives and constructs its own inner world to interact with the outside world. From a Predictive Processing perspective, the purpose of an intervention would be to cause a positive surprise and a high prediction error that will violate existing predictions and update the brain's internal model.

Do we need to change?

Osteopathic clinical practice is by and large characterised by complexity. Many of our patients present with an array of bodily symptoms that frequently do not fit a particular clinical condition or are suitable to a biomechanically-biased model of osteopathic care. It is therefore crucial that we develop a model of osteopathic care which fuses the conceptual basis of osteopathy with predictive processing models and the science of interoception, allostatic regulation and affective touch, for example. The model will enable practitioners to effectively evaluate their patients within a biopsychosocial(spiritual) framework while taking into account how their patients' embodied brains construct their internal models of disease, health and wellbeing. Treatment should be underpinned by the effective use of language and hands-on osteopathic treatment techniques/affective touch and integrated with cognitive reassurance, graded exposure to movement and exercise, and mindfulness-based approaches.

Essay based on Presentations at COME to Quantum Global Conference 18-19th October 2019, Catania, Italy

Esteves JE (2019). Predictive processing and allostatic regulation in clinical practice. Keynote Presentation at COME to Quantum Global - Allostasis the essence of clinical practice. 18-19th October 2019, Catania, Italy.

Esteves JE (2019). Allostatic regulation and symptom management within a biopsychosocial-predictive processing framework. Keynote Presentation at COME to Quantum Global - Allostasis the essence of clinical practice. 18-19th October 2019, Catania, Italy.

Acknowledgements - Dr Francesco Cerritelli, Professor Vaucher, Dr Oliver Thomson, Dr Hilary Abbey

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