Functional motor disorders (FMDs) are distinguished by signs that lack congruence with recognised patterns of organic disease and show inconsistency over time. Their pathophysiology is poorly understood, but there is evidence that irregularities in perceptual and cognitive processing lie at the heart of these conditions. Here, we draw on a predictive coding account of functional neurological disorders to study perceptual decision-making in three groups: 20 patients with FMDs (14 with functional movements and 6 with functional weakness), 20 with phenotypically-matched organic motor disorders, and 20 age-matched healthy controls. We examine four cognitive domains with putative roles in FMD pathogenesis: attention, expectations, sensory processing (perceptual sensitivity), and metacognition (introspective evaluation of performance). We augmented a dual-task paradigm, manipulating the visual contrast required for target detection to examine these domains in one design. With sensory input (stimulus contrast) psychometrically adjusted to staircase target detection at a fixed level for all groups, the FMD group exhibited statistically equivalent attentional, expectational and metacognitive processing to healthy controls. However, we demonstrate Bayesian evidence and a frequentist trend that FMD patients require higher visual contrast than controls to maintain the same detection sensitivity (BF10 = 8.1, pholm = .066). This was statistically equivalent to the visual contrast required by the organic group, and unlikely to be accounted for by medication use or comorbid psychopathology. The organic group showed differences in processing of attention and expectations for target detection that were not observed in either healthy controls or the functional group. The distinctive behavioural profile of FMDs may arise from abnormalities in basic sensory processing, while higher attentional, expectational and metacognitive mechanisms remain intact. Conceptualising functional neurological disorders under a predictive coding account may consolidate and refine existing pathophysiological theories about them.

中文翻译：

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在功能性运动障碍中完整注意和元认知的情况下提高视觉对比度阈值。

功能性运动障碍（FMD）的特征是缺乏与公认的器质性疾病模式的一致性，并且随着时间的推移表现出不一致。他们的病理生理学知之甚少，但是有证据表明，感知和认知过程中的不规则性是这些疾病的核心。在这里，我们使用功能性神经疾病的预测编码帐户来研究三组的知觉决策：20例FMD患者（14例具有功能性运动，6例具有功能性弱点），20例在表型上匹配的器质性运动障碍，以及20例年龄匹配的健康对照。我们研究了在FMD发病机理中具有推定作用的四个认知领域：注意力，期望，感觉处理（感知敏感性）和元认知（内省性表现评估）。我们增强了双重任务范式，操纵目标检测所需的视觉对比度，以在一种设计中检查这些域。通过对所有组的心理输入进行心理调节（刺激对比），以固定水平进行阶梯目标检测，FMD组在统计学上等效于注意，期望和元认知过程，与健康对照组相同。但是，我们证明了贝叶斯证据和频繁趋势，即FMD患者需要比对照组更高的视觉对比度才能保持相同的检测灵敏度（BF10 = 8.1，pholm = .066）。这在统计学上等同于有机体组所需的视觉对比，并且不太可能由药物使用或合并症心理病理学解释。有机物组在注意过程和目标检测期望方面显示出差异，在健康对照组或功能组中均未观察到。FMD的独特行为特征可能来自基本的感觉处理异常，而更高的注意力，期望和元认知机制仍然完好无损。在预测编码下将功能性神经系统疾病概念化可以巩固和完善关于它们的现有病理生理学理论。