Functional neurological disorder, suggestion and virtual reality: neuroanatomical and computational perspectives.

This Opinion piece addresses links between functional neurological disorder, hypnosis and suggestion, and their potential modulation by virtual reality (VR) in neuroanatomical and computational terms. The cortical hierarchy provides an anatomical basis for differing neurocognitive and computational theories applied to suggested effects and functional symptoms-hierarchical predictive coding, top-down cortical feedback and signal routing, and attractor dynamics. Each theory views the brain as a graded anatomical hierarchy with bidirectional influences between levels. Each considers that representations privileged by heightened attention (whether by cognitive control or automatic processes) alter the pre-conscious 'editing' of experience to generate suggested effects and functional symptoms. This occurs through an increase in top-down signals relative to bottom-up signals across the cortical hierarchy, resulting in enhanced activation of selected neuronal populations in intermediate levels. This alters the interpretation of bottom-up signals or radically misrepresents the presence or absence of bottom-up signals to higher levels. By contrast, VR influences experience by simulating the bottom-up effects of veridical sensory input to sensory processing streams. Despite the shared framework of the cortical hierarchy, the theories differ in important respects. Implications for future research and combining suggestions and VR to treat functional symptoms are considered. This article is part of the discussion meeting issue 'Digital healthcare for the management of functional neurological disorders'.