Functional Neurological Disorder as a Disorder of Sensorimotor Inference Under Stress: A Neurocomputational Account

Functional neurological disorder (FND) sits at the intersection of psychiatry and neurology, producing disabling motor and sensory symptoms despite intact peripheral pathways. FND may reflect altered precision weighting within neural systems, such that the brain generates the dysfunction it predicts. Stress is among the most consistent precipitants, yet how it produces functional symptoms remains mechanistically unspecified. The present account proposes that FND arises from over-precision of maladaptive priors relative to afferent sensory evidence within insula–cingulate–sensorimotor circuits under stress-mediated neuromodulation. Chronic or traumatic stress is proposed to recalibrate precision through hypothalamic–pituitary–adrenal axis dysregulation and noradrenergic modulation. The proposed result is that overly precise expectations about bodily dysfunction dominate proprioceptive and motor inference and override ascending feedback. What may distinguish FND from other stress-linked conditions is the sensorimotor locus of these priors and their implementation in motor control systems. The mechanism is mapped onto circuits including the anterior insula, dorsal anterior cingulate cortex, supplementary motor area, and temporoparietal junction. Falsifiable predictions are derived at algorithmic, neural, and physiological levels, each with an explicit disconfirmation criterion. A discriminative prediction separates this account from competing models. Attenuation of insula prediction-error signalling during voluntary movement should be greater with stress-system dysregulation and may ease under acute reduction of arousal, whereas sensory-gain and attentional-capture models predict no such modulation. The framework offers a possible account of why verbal reassurance alone may be insufficient and provides a computational basis for physiotherapy and, if validated, for pre-treatment precision profiling to help guide treatment planning.