Aversive stimuli exacerbate defensive motor behaviour in motor conversion disorder

Abstract

A B S T R A C TConversion disorder or functional neurological symptom disorder (FND) can affect the voluntary motor system, without an organic cause. Functional symptoms are thought to be generated unconsciously, arising from underlying psychological stressors. However, attempts to demonstrate a direct relationship between the limbic system and disrupted motor function in FND are lacking. We tested whether negative affect would exacerbate alterations of motor control and corresponding brain activations in individuals with FND. Ten patients and ten healthy controls produced an isometric precision-grip contraction at 10% of maximum force while either viewing visual feedback of their force output, or unpleasant or pleasant emotional images (without feedback). Force magnitude was continuously recorded together with change in brain activity using fMRI. For controls, force output decayed from the target level while viewing pleasant and unpleasant images. Patients however, maintained force at the target level without decay while viewing unpleasant images, indicating a pronounced effect of negative affect on force output in FND. This emotional modulation of force control was associated with different brain activation patterns between groups. Contrasting the unpleasant with the pleasant condition, controls showed increased activity in the inferior frontal cortex and pre-supplementary motor area, whereas patients had greater activity in the cerebellum (vermis), posterior cingulate cortex, and hippocampus. Engagement of a cerebellar-limbic network in patients is consistent with heightened processing of emotional salience, and supports the role of the cerebellum in freezing responses in the presence of aversive events. These data highlight a possible neural circuit through which psychological stressors elicit defensive behaviour and modulate motor function in FND.

Self‐reference, emotion inhibition and somatosensory disturbance: preliminary investigation of network perturbations in conversion disorder

“…Our finding of decreased connectivity between the MTL (involved in autobiographical memory) and sensorimotor networks in CD may support theories that repression of stressful or traumatic life events leads to sensorimotor disturbances . It was suggested that psychological defense mechanisms, such as repression or dissociation, are used to ‘block’ patients’ awareness of traumatic memories, leading to the symptoms presented in CD .…”

Emotional processing in functional neurological disorder: a review, biopsychosocial model and research agenda

“…Blakemore et al ,39 for example, found evidence for facilitated manual output force in people with FND-movt while viewing negative IAPS images. Fiess et al 40 reported increased FND symptoms and reduced discomfort threshold after intentional emotion regulation during IAPS exposure.…”

Autonomic and subjective responsivity to emotional images in people with dissociative seizures

“…Altered responsivity to general affective images has been investigated experimentally in individuals diagnosed with disorders that share risk factors and/or clinical characteristics with DS, such as borderline personality disorder (Herpertz, Kunert, Schwenger, & Sass, 1999) and depersonalization disorder (Sierra et al, 2002). Differences in neural activity have also been reported in people with other conversion disorders relative to healthy controls, during processing of affective pictures (Blakemore, Sinanaj, Galli, Aybek, & Vuilleumier, 2016;Fiess, Rockstroh, Schmidt, Wienbruch, & Steffen, 2016). However, to date, only one study has examined more general emotional responding in people with DS in the laboratory.…”