Background and Purpose— Evidence suggests that therapy can be effective in recovering from aphasia, provided that it consists of socially embedded, intensive training of behaviorally relevant tasks. However, the resources of healthcare systems are often too limited to provide such treatment at sufficient dosage. Hence, there is a need for evidence-based, cost-effective rehabilitation methods. Here, we asked whether virtual reality-based treatment grounded in the principles of use-dependent learning, behavioral relevance, and intensity positively impacts recovery from nonfluent aphasia. Methods— Seventeen patients with chronic nonfluent aphasia underwent intensive therapy in a randomized, controlled, parallel-group trial. Participants were assigned to the control group (N=8) receiving standard treatment or to the experimental group (N=9) receiving augmented embodied therapy with the Rehabilitation Gaming System for aphasia. All Rehabilitation Gaming System for aphasia sessions were supervised by an assistant who monitored the patients but did not offer any elements of standard therapy. Both interventions were matched for intensity and materials. Results— Our results revealed that at the end of the treatment both groups significantly improved on the primary outcome measure (Boston Diagnostic Aphasia Examination: control group, P =0.04; experimental group, P =0.01), and the secondary outcome measure (lexical access—vocabulary test: control group, P =0.01; experimental group, P =0.007). However, only the Rehabilitation Gaming System for aphasia group improved on the Communicative Aphasia Log ( P =0.01). The follow-up assessment (week 16) demonstrated that while both groups retained vocabulary-related changes (control group, P =0.01; experimental group, P =0.007), only the Rehabilitation Gaming System for aphasia group showed therapy-induced improvements in language ( P =0.01) and communication ( P =0.05). Conclusions— Our results demonstrate the effectiveness of Rehabilitation Gaming System for aphasia for improving language and communication in patients with chronic aphasia suggesting that current challenges faced by the healthcare system in the treatment of stroke might be effectively addressed by augmenting traditional therapy with computer-based methods. Clinical Trial Registration— URL: https://www.clinicaltrials.gov . Unique identifier: NCT02928822.

Body ownership is critically dependent on multimodal integration as for instance revealed in the Rubber Hand Illusion (RHI) and a number of studies which have addressed the neural correlates of the processes underlying this phenomenon. Both experimental and clinical research have shown that the structures underlying body ownership seem to significantly overlap with those of motor control including the parietal and ventral premotor cortices, Temporal Parietal Junction (TPJ) and the insula. This raises the question of whether this structural overlap between body ownership and motor control structures is of any functional significance. Here, we investigate the specific question of whether experimentally induced ownership over a virtual limb can modulate the performance of that limb in a simple sensorimotor task. Using a Virtual reality (VR) environment we modulate body ownership in three experimental conditions with respect to the (in)congruence of stimulus configurations. Our results show that the degree of ownership directly modulates motor performance. This implies that body ownership is not exclusively a perceptual and/or subjective multimodal state but that it is tightly coupled to systems for decision-making and motor control.

Our understanding of body ownership largely relies on the so-called Rubber Hand Illusion (RHI). In this paradigm, synchronous stroking of the real and the rubber hands leads to an illusion of ownership of the rubber hand provided that it is physically, anatomically, and spatially plausible. Self-attribution of an artificial hand also occurs during visuomotor synchrony. In particular, participants experience ownership over a virtual or a rubber hand when the visual feedback of self-initiated movements follows the trajectory of the instantiated motor commands, such as in the Virtual Hand Illusion (VHI) or the moving Rubber Hand Illusion (mRHI). Evidence yields that both when the cues are triggered externally (RHI) and when they result from voluntary actions (VHI and mRHI), the experience of ownership is established through bottom-up integration and top-down prediction of proximodistal cues (visuotactile or visuomotor) within the peripersonal space. It seems, however, that depending on whether the sensory signals are externally (RHI) or self-generated (VHI and mRHI), the top-down expectation signals are qualitatively different. On the one hand, in the RHI the sensory correlations are modulated by top-down influences which constitute empirically induced priors related to the internal (generative) model of the body. On the other hand, in the VHI and mRHI body ownership is actively shaped by processes which allow for continuous comparison between the expected and the actual sensory consequences of the actions. Ample research demonstrates that the differential processing of the predicted and the reafferent information is addressed by the central nervous system via an internal (forward) model or corollary discharge. Indeed, results from the VHI and mRHI suggest that, in action-contexts, the mechanism underlying body ownership could be similar to the forward model. Crucially, forward models integrate across all self-generated sensory signals including not only proximodistal (i.e., visuotactile or visuomotor) but also purely distal sensory cues (i.e., visuoauditory). Thus, if body ownership results from a consistency of a forward model, it will be affected by the (in)congruency of purely distal cues provided that they inform about action-consequences and are relevant to a goal-oriented task. Specifically, they constitute a corrective error signal. Here, we explicitly addressed this question. To test our hypothesis, we devised an embodied virtual reality-based motor task where action outcomes were signaled by distinct auditory cues. By manipulating the cues with respect to their spatial, temporal and semantic congruency, we show that purely distal (visuoauditory) feedback which violates predictions about action outcomes compromises both performance and body ownership. These results demonstrate, for the first time, that body ownership is influenced by not only externally and self-generated cues which pertain to the body within the peripersonal space but also those arising outside of the body. Hence, during goal-oriented tasks...

Future applications of robotic technologies will involve interactions with non-expert humans as machines will assume the role of companions, teachers or healthcare assistants. In all those tasks social behavior is a key ability that needs to be systematically investigated and modelled at the lowest level, as even a minor inconsistency of the robot’s behavior can greatly affect the way humans will perceive it and react to it. Here we propose an integrated architecture for generating a socially competent robot.We validate our architecture using a humanoid robot, demonstrating that gaze, eye contact and utilitarian emotions play an essential role in the psychological validity or social salience of Human-Robot Interaction (HRI). We show that this social salience affects both the empathic bonding between the human and a humanoid robot and, to a certain extent, the attribution of a Theory of Mind (ToM). More specifically, we investigate whether these social cues affect other utilitarian aspects of the interaction such as knowledge transfer within a teaching context.