Publications (27) View all
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Article: Dissociations and similarities in motor intention and motor awareness: the case of anosognosia for hemiplegia and motor neglect.
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ABSTRACT: OBJECTIVES: To confront motor awareness in anosognosia for hemiplegia (AHP), where paralyzed patients deny their motor impairment, and in motor neglect (MN), where non-paralyzed patients behave as if they were paretic. METHODS: Eight right-brain-damaged-patients, 4 hemiplegic (2 with and 2 without AHP) and 4 non-hemiplegic (2 with only perceptual-neglect and 2 with also MN) were evaluated with a bimanual motor battery, before and after examiner's reinforcement to use the contralesional limb. The requested bimanual movements could be either symmetric or asymmetric, either intransitive or transitive (with/without objects). We compared the examiner's evaluation of patients' performance with the patients' self-evaluation of their own motor capability (explicit knowledge). We also evaluated the presence/absence of compensatory unimanual strategies that, if present, suggests implicit knowledge of the motor deficit. RESULTS: We found significant differences between conditions only in MN patients, whose performance was better after the examiner's reinforcement than before it, during symmetric than asymmetric movements and during intransitive than transitive movements. As for motor awareness, we found a lack of explicit and implicit knowledge in both AHP and MN patients. CONCLUSION: Although different in terms of motor intention and motor planning, AHP and MN are both characterised by anosognosia for the motor impairment.Journal of Neurology Neurosurgery & Psychiatry 09/2013; 84(4):416–419. · 4.76 Impact Factor -
Article: Embodiment of an alien hand interferes with intact-hand movements.
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ABSTRACT: Can we fully incorporate into our body schema the body parts of others, altering our sense of ownership [1]? And, to what extent, given the tight link between body and motor representations, does an altered sense of body-ownership affect motor awareness [2] and the sense of agency [3,4]? The new study we report here demonstrates that a body part of one individual can become so deeply embedded in another's sensory-motor circuits as to have objective effects on the latter's motor execution. Indeed, we found, in right-brain-damaged hemiplegic patients who identified another person's hand as belonging to themselves, significant interference effects of the alien hand movements on the actual movements of their own intact hand.Current biology: CB 01/2013; 23(2):R57-8. · 10.99 Impact Factor -
Article: In your place: neuropsychological evidence for altercentric remapping in embodied perspective taking.
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ABSTRACT: Humans are able to mentally adopt the spatial perspective of others and represent the visual world from their point of view. Here, we present neuropsychological evidence that information inaccessible from an egocentric perspective can be accessed from the perspective of another person. Patients affected by left neglect were asked to describe arrays of objects from their own egocentric perspective, from an opposite perspective (disembodied perspective taking), and from the point of view of another person actually seated in front of them (embodied perspective taking). Although disembodied perspective-taking ameliorated neglect severity, there was an even stronger positive effect of embodied perspective-taking: items presented on the left and neglected when reported from the egocentric perspective were instead recovered when patients assumed the perspective of the other. These findings suggest that perspective-taking entails an altercentric remapping of space, i.e. remapping of objects and locations coded with reference to the other person's body.Social Cognitive and Affective Neuroscience 01/2013; 8(2):165-170. · 6.13 Impact Factor -
Article: Temporal coupling due to illusory movements in bimanual actions: Evidence from anosognosia for hemiplegia.
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ABSTRACT: In anosognosia for hemiplegia, patients may claim having performed willed actions with the paralyzed limb despite unambiguous evidence to the contrary. Does this false belief of having moved reflect the functioning of the same mechanisms that govern normal motor performance? Here, we examined whether anosognosics show the same temporal constraints known to exist during bimanual movements in healthy subjects. In these paradigms, when participants simultaneously reach for two targets of different difficulties, the motor programs of one hand affect the execution of the other. In detail, the movement time of the hand going to an easy target (i.e., near and large), while the other is going to a difficult target (i.e., far and small), is slowed with respect to unimanual movements (temporal coupling effect). One right-brain-damaged patient with left hemiplegia and anosognosia, six right-brain-damaged patients with left hemiplegia without anosognosia, and twenty healthy subjects were administered such a bimanual task. We recorded the movement times for easy and difficult targets, both in unimanual (one target) and bimanual (two targets) conditions. We found that, as healthy subjects, the anosognosic patient showed coupling effect. In bimanual asymmetric conditions (when one hand went to the easy target and the other went to the difficult target), the movement time of the non-paralyzed hand going to the easy target was slowed by the 'pretended' movement of the paralyzed hand going to the difficult target. This effect was not present in patients without anosognosia. We concluded that in anosognosic patients, the illusory movements of the paralyzed hand impose to the non-paralyzed hand the same motor constraints that emerge during the actual movements. Our data also support the view that coupling relies on central operations (i.e., activation of intention/programming system), rather than on online information from the periphery.Cortex 09/2012; · 6.08 Impact Factor -
Article: Functional independence between numerical and visual space: Evidence from right brain-damaged patients.
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ABSTRACT: What is the relationship between numerical and visual space? Here we tried to shed new light on this debated issue investigating whether and how the two forms of representation are associated or dissociated when co-activated. We carried out a series of visual-numerical bisection experiments on a large group of right brain-damaged patients (N=32) with and without left neglect. We examined (a) the degree of association between the pathological rightward error in the bisection of numerical intervals and left neglect (Experiment 1); (b) if the size of the numerical interval modulates spatial errors in bisection tasks in which numerical and visual space representations are co-activated (Experiment 2). The results showed that (a) numerical bisection error and left spatial neglect are doubly dissociated and that, when both are present, they are not correlated; (b) the size of the numerical interval did not affect the spatial bisection error but influenced the numerical bisection error. These data suggest that attentional processes involved in the navigation along visual space and numerical internal representations are independent neurocognitive operations. We must emphasize that our findings should be taken with caution because they are based mainly on negative results.Cortex 04/2012; 48(10):1351-8. · 6.08 Impact Factor
