Constructing and updating motor awareness: experimental studies in Anosognosia for Hemiplegia

Body awareness, the sense that our body is ours, is constructed by dynamic integration of several sensory modalities, including exteroceptive (originating outside the body), and interoceptive (originating within) and can be divided into awareness of body ownership and of motor deficits. This study examined the contribution of different, top-down and bottom-up inter-acting, cognitive and emotional factors, in the construction of body and motor awareness, by focusing on Anosognosia for Hemiplegia (AHP), a syndrome of motor awareness disruption. AHP refers to the inability of (usually) right hemisphere stroke patients to acknowledge their motor deficits. Clinical presentation of AHP varies, with some patients even displaying disruption of the sense of body ownership. Current AHP theories, based on predictive coding, suggest belief op-timisation, based on a multilevel system of top-down predictions and bottom-up feedback, is disrupted due to neurological damage, combined with prior patient’s traits. Combinations of disruptions account for the variability of AHP and affect the patient’s ability to incorporate feedback about their paralysis into their pre-existing schema of themselves, remaining fixated into delusion-like beliefs. Under the same framework, right hemisphere patients with and without anosognosia were recruited from the NHS setting, underwent neuro-psychological assessments and participated in experimental studies examin-ing this model on different levels. At the sensory level, the effect of self- and affective touch was examined, given their interoceptive properties and role affecting bodily awareness. AHP patients’ belief updating ability was tested, by examining how their performance predictions and confidence change fol-lowing motor failures. Given anosognosics’ deficits in perspective taking and proper emotion processing, their ability to update beliefs about themselves and others on cognitive and emotional level and their ability to spontaneously adopt another person’s perspective were examined. Given the elements of denial observed in AHP, presence of memory repression was examined by means of a memory test with deficit-related content