Interoceptive disruption in functional neurological disorder: a multimodal brain imaging study

This multimodal brain imaging study investigated functional MRI (fMRI) neural processing of cardiac interoceptive signals in 38 patients with functional neurological disorder (FND) compared to 38 healthy controls (HCs). Additionally, we characterized how brain fMRI responses during heartbeat counting (interoception) vs. tone counting (exteroception) or rest related to grey matter volume, interoceptive awareness, and psychopathology scores. For both interoception vs. rest and interoception vs. exteroception contrasts, principal component analyses showed that principal component 1 (PC1) as derived from all study participants was comprised primarily of salience, ventral attention and sensorimotor network co-activations, along with default mode and visual processing network co-deactivations. Compared to HCs, patients with FND showed reduced contribution to these PC1 co-activation/co-deactivations patterns in both interoception vs. exteroception and interoception vs. rest contrasts; only the interoception vs. exteroception between-group fMRI findings held adjusting for depression/anxiety scores, antidepressant use and FND subtype. For the interoception vs. rest contrast, increasingly negative PC1 contribution scores positively correlated with decreased cingulate gyrus volumes and increased psychopathology scores. This multimodal brain imaging study underscores a role for salience and default-mode networks in the pathophysiology of FND, and sets the stage for comprehensive research efforts further contextualizing the mechanistic importance of altered interoception in patients with FND.