Recently, a monothematic delusion of body ownership due to brain damage (i.e., the embodiment of someone else's body part within the patient's sensorimotor system) has been extensively investigated. Here we aimed at defining in-depth the clinical features and the neural correlates of the delusion. Ninety-six stroke patients in a sub-acute or chronic phase of the illness were assessed with a full ad-hoc protocol to evaluate the embodiment of an alien arm under different conditions. A sub-group of seventy-five hemiplegic patients was also evaluated for the embodiment of the movements of the alien arm. Fifty-five patients were studied to identify the neural bases of the delusion by means of voxel-based lesion-symptom mapping approach. Our results show that, in forty percent of the whole sample, simply viewing the alien arm triggered the delusion, but only if it was a real human arm and that was seen from a 1st person perspective in an anatomically-correct position. In the hemiplegic sub-group, the presence of the embodiment of the alien arm was always accompanied by the embodiment of its passive and active movements. Furthermore, the delusion was significantly associated to primary proprioceptive deficits and to damages of the corona radiata and the superior longitudinal fasciculus. To conclude, we show that the pathological embodiment of an alien arm is well-characterized by recurrent and specific features and might be explained as a disconnection deficit, mainly involving white matter tracts. The proposed exhaustive protocol can be successfully employed to assess stroke-induced disorders of body awareness, unveiling even their more undetectable or covert clinical forms.

最近，已经广泛研究了由于脑部损伤（即，患者身体的一部分在患者感觉运动系统中的体现）而导致的身体所有权的单主题错觉。在这里，我们旨在深入定义妄想的临床特征和神经相关性。对亚急性或慢性病阶段的96例中风患者进行了全面的即席方案评估，以评估异物臂在不同条件下的表现。还对75名偏瘫患者的亚组进行了异物臂运动体现的评估。研究了55名患者，以基于体素的病灶-症状标测方法识别妄想的神经基础。我们的结果表明，在整个样本的40％中，只需查看异物手臂便会引起错觉，但前提是该异物是真实的人手臂，并且是从第一人称视角在解剖学上正确的位置看到的。在偏瘫分组中，外来手臂的体现总是伴随着其被动和主动运动的体现。此外，这种妄想与原发性本体感受缺陷以及电晕放射线和上纵筋膜的损害显着相关。总而言之，我们表明，异物臂的病理表现通过反复出现的特定特征而具有良好的特征，并且可以解释为断路缺陷，主要涉及白质束。拟议的详尽方案可以成功地用于评估中风诱发的身体意识障碍，