Functional neurological disorder (FND) presents disabling symptoms that fluctuate, migrate across systems, and yet routinely show preserved structural integrity-features that can frustrate diagnosis and patient education. Crucially, these symptoms are genuine and reflect altered brain regulation across multiple systems rather than tissue damage or conscious control. This paper offers a clinically usable account of these puzzles by reframing FND as a disorder of precision control within predictive coding. The brain's confidence (precision) in its own predictions is modelled as a dynamic quantity that can surge with arousal, settle back toward baseline, and slowly recalibrate over longer periods. Placing this mechanism in a four-level hierarchy (affective, interoceptive, proprioceptive, spinal) shows how arousal can temporarily make an unhelpful expectation dominate, suppress corrective feedback, and produce motor, sensory, cognitive, or visceral symptoms-often in combination. The same dynamics explain rule-in positive signs such as distractibility, entrainment, and give-way weakness, and clarify the lived experience of reduced agency without implying wilfulness or malingering. For clinicians, the framework provides an intuitive way to explain symptoms to patients ('a temporary gain miscalibration that overweights predictions and underweights sensory feedback'), and to justify why physiotherapy (amplifying proprioceptive feedback), psychotherapy (reducing arousal), and mindfulness or biofeedback (raising the effective threshold for arousal-driven 'gain spikes') can all help by recalibrating that weighting. The framework also yields concrete, falsifiable tests, linking bedside observation to measurable biomarkers and offering ways to refine it further. By centring dynamic precision, the account unifies diagnosis, communication, and treatment planning, and provides a mechanistic foundation for precision-guided care in FND.
Abstract
Journal Article
eng
41823406
Lyndon, Stanley. "Precision Dynamics of Predictive Coding in Functional Neurological Disorder." Brain : a Journal of Neurology, 2026.
Lyndon S. Precision dynamics of predictive coding in functional neurological disorder. Brain. 2026.
Lyndon, S. (2026). Precision dynamics of predictive coding in functional neurological disorder. Brain : a Journal of Neurology. https://doi.org/10.1093/brain/awag101
Lyndon S. Precision Dynamics of Predictive Coding in Functional Neurological Disorder. Brain. 2026 Mar 13; PubMed PMID: 41823406.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR
T1 - Precision dynamics of predictive coding in functional neurological disorder.
A1 - Lyndon,Stanley,
Y1 - 2026/03/13/
PY - 2025/11/26/received
PY - 2026/02/16/revised
PY - 2026/3/13/medline
PY - 2026/3/13/pubmed
PY - 2026/3/13/entrez
KW - active inference
KW - autonomic arousal
KW - dynamic precision control
KW - functional neurological disorder
KW - loss of agency
KW - predictive coding
JF - Brain : a journal of neurology
JO - Brain
N2 - Functional neurological disorder (FND) presents disabling symptoms that fluctuate, migrate across systems, and yet routinely show preserved structural integrity-features that can frustrate diagnosis and patient education. Crucially, these symptoms are genuine and reflect altered brain regulation across multiple systems rather than tissue damage or conscious control. This paper offers a clinically usable account of these puzzles by reframing FND as a disorder of precision control within predictive coding. The brain's confidence (precision) in its own predictions is modelled as a dynamic quantity that can surge with arousal, settle back toward baseline, and slowly recalibrate over longer periods. Placing this mechanism in a four-level hierarchy (affective, interoceptive, proprioceptive, spinal) shows how arousal can temporarily make an unhelpful expectation dominate, suppress corrective feedback, and produce motor, sensory, cognitive, or visceral symptoms-often in combination. The same dynamics explain rule-in positive signs such as distractibility, entrainment, and give-way weakness, and clarify the lived experience of reduced agency without implying wilfulness or malingering. For clinicians, the framework provides an intuitive way to explain symptoms to patients ('a temporary gain miscalibration that overweights predictions and underweights sensory feedback'), and to justify why physiotherapy (amplifying proprioceptive feedback), psychotherapy (reducing arousal), and mindfulness or biofeedback (raising the effective threshold for arousal-driven 'gain spikes') can all help by recalibrating that weighting. The framework also yields concrete, falsifiable tests, linking bedside observation to measurable biomarkers and offering ways to refine it further. By centring dynamic precision, the account unifies diagnosis, communication, and treatment planning, and provides a mechanistic foundation for precision-guided care in FND.
SN - 1460-2156
UR - https://www.unboundmedicine.com/prime/citation/41823406/Precision_dynamics_of_predictive_coding_in_functional_neurological_disorder.
DB - PRIME
DP - Unbound Medicine
ER -
