Marotta Angela, Bombieri Federica, Zampini Massimiliano, Schena Federico, Dallocchio Carlo, Fiorio Mirta, Tinazzi Michele
Department of Neurosciences, Biomedicine and Movement Sciences, University of VeronaVerona, Italy.
Neurology Unit, Neuroscience Department, Azienda Ospedaliera Universitaria IntegrataVerona, Italy.
Front Hum Neurosci. 2017 Jun 6;11:291. doi: 10.3389/fnhum.2017.00291. eCollection 2017.
Functional movement disorders (FMD) are characterized by motor symptoms (e.g., tremor, gait disorder, and dystonia) that are not compatible with movement abnormalities related to a known organic cause. One key clinical feature of FMD is that motor symptoms are similar to voluntary movements but are subjectively experienced as involuntary by patients. This gap might be related to abnormal self-recognition of bodily action, which involves two main components: sense of agency and sense of body ownership. The aim of this study was to systematically investigate whether this function is altered in FMD, specifically focusing on the subjective feeling of agency, body ownership, and their interaction during normal voluntary movements. Patients with FMD ( = 21) and healthy controls ( = 21) underwent the moving Rubber Hand Illusion (mRHI), in which passive and active movements can differentially elicit agency, ownership or both. Explicit measures of agency and ownership were obtained via a questionnaire. Patients and controls showed a similar pattern of response: when the rubber hand was in a plausible posture, active movements elicited strong agency and ownership; implausible posture of the rubber hand abolished ownership but not agency; passive movements suppressed agency but not ownership. These findings suggest that explicit sense of agency and body ownership are preserved in FMD. The latter finding is shared by a previous study in FMD using a static version of the RHI, whereas the former appears to contrast with studies demonstrating altered implicit measures of agency (e.g., sensory attenuation). Our study extends previous findings by suggesting that in FMD: (i) the sense of body ownership is retained also when interacting with the motor system; (ii) the subjective experience of agency for voluntary tapping movements, as measured by means of mRHI, is preserved.
功能性运动障碍（FMD）的特征是运动症状（如震颤、步态障碍和肌张力障碍），这些症状与已知器质性病因相关的运动异常不相符。FMD的一个关键临床特征是运动症状与随意运动相似，但患者主观上感觉是不自主的。这种差异可能与身体动作的自我识别异常有关，身体动作的自我识别涉及两个主要成分：能动感和身体归属感。本研究的目的是系统地调查FMD患者的这一功能是否发生改变，特别关注在正常随意运动过程中的能动感、身体归属感主观感受及其相互作用。FMD患者（n = 21）和健康对照者（n = 21）接受了移动橡胶手错觉（mRHI）测试，其中被动和主动运动可分别引发能动感、归属感或两者皆有。通过问卷获得了关于能动感和归属感的明确测量结果。患者和对照者表现出相似的反应模式：当橡胶手处于合理姿势时，主动运动引发强烈的能动感和归属感；橡胶手姿势不合理则消除归属感但不消除能动感；被动运动抑制能动感但不抑制归属感。这些发现表明，FMD患者的明确能动感和身体归属感得以保留。先前一项针对FMD患者使用静态版本RHI的研究也得出了后一项结果，而前一项结果似乎与那些表明能动感的内隐测量发生改变（如感觉衰减）的研究形成对比。我们的研究扩展了先前的发现，表明在FMD患者中：（i）即使在与运动系统相互作用时，身体归属感也得以保留；（ii）通过mRHI测量的自愿敲击运动的能动感主观体验得以保留。
