Search

Humans experience their own body as unitary and monolithic in nature. However, recent findings in cognitive neuroscience seem to suggest that body awareness has a complex and multifaceted structure that can be dissociated in several subcomponents, possibly underpinned by different brain circuits. In the present paper, we focus on a recently reported neuropsychological disorder of body ownership in which patients misattribute to themselves someone else’s arm and its movements. As first, we briefly review the clinical and functional features of this disorder. Secondly, we attempt to explain the nature of the delusion and to gain new hints regarding the mechanisms subserving the construction and the maintenance of the sense of body ownership in the intact brain functioning. [ABSTRACT FROM AUTHOR]

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., (Copyright © 2020 Elsevier Ltd. All rights reserved.)