What I think she thinks about my body: Social inferences about disability-related content in anosognosia for hemiplegia

Abstract

The neuropsychological disorder of anosognosia for hemiplegia (AHP) can offer unique insights into the neurocognitive processes of body consciousness and representation. Previous studies have found associations between selective social cognition deficits and anosognosia. In this study, we examine how such social cognition deficits may directly interact with representations of one’s body as disabled in AHP. To this end, we modified a set of previously validated Theory of Mind stories to create content that was related to post-stroke paralysis and to investigate differences between right hemisphere damage patients with (n = 19) and without (n = 19) AHP. We expected AHP patients to perform worse than controls when trying to infer paralysis-related mental states, and explored whether such differences further depended on the kind of inference patients were asked to perform (e.g. from a first versus a third person perspective). Using an advanced structural neuroimaging technique, we expected selective social cognitive deficits to be associated with posterior parietal cortex lesions, and the difficulty to associate self -beliefs with paralysis during mentalising to be associated with frontoparietal disconnections. Group and individual level results revealed that AHP patients performed worse than HP controls when trying to infer paralysis-related mental states, possibly driven by both social cognition deficits per se and more specific difficulties to take the perspective of paralysed individual. Lesion analyses results were significant only at exploratory levels, revealing some of the hypothesised lesions but also unexpected white matter disconnections in the posterior body and splenium of the corpus collosum as related to deficits-related self-referent perspective taking. The study has implications for the multi-layered nature of body awareness, including abstract, social perspectives and beliefs about the body.