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Although multisensory integration (MSI) has been extensively studied, the underlying mechanisms remain a topic of ongoing debate. Here we investigate these mechanisms by comparing MSI in healthy controls to a clinical population with spinal cord injury (SCI). Deafferentation following SCI induces sensorimotor impairment, which may alter the ability to synthesize cross-modal information. We applied mathematical and computational modeling to reaction time data recorded in response to temporally congruent cross-modal stimuli. We found that MSI in both SCI and healthy controls is best explained by cross-modal perceptual competition, highlighting a common competition mechanism. Relative to controls, MSI impairments in SCI participants were better explained by reduced stimulus salience leading to increased cross-modal competition. By combining traditional analyses with model-based approaches, we examine how MSI is realized during normal function, and how it is compromised in a clinical population. Our findings support future investigations identifying and rehabilitating MSI deficits in clinical disorders. [ABSTRACT FROM AUTHOR]

According to the dimensional approach to psychosis, there is a continuum from low schizotypy to schizophrenia patients. The temporal aspect of sensory processing seems to be compromised across such continuum, as suggested by different studies separately investigating unisensory or multisensory domains. Most of these studies have so far focused primarily on the temporal processing of visual and auditory stimuli, either in schizotypy or schizophrenia, while leaving the tactile domain and the integration of touch with other senses mostly unexplored. Given the relevance of body-related perceptual abnormalities for psychosis proneness, we aimed at filling this gap in the literature across two studies. We asked participants with increasing levels of schizotypy (study 1) and schizophrenia patients (study 2) to perform three simultaneity judgement tasks: a unimodal tactile task, a unimodal auditory task and a bimodal audio-tactile task. Each task allowed estimating a simultaneity range (SR), as a proxy of the individual tolerance to asynchronies in the tactile, auditory and audio-tactile domains, respectively. Results showed larger SRs as the level of schizotypy increases. Specifically, the linear effect of schizotypy levels on the audio-tactile task was stronger than on the auditory task, which in turn was greater than the effect on the tactile task (study 1). Differently, schizophrenia patients showed larger SRs than controls in all the three tasks (study 2). The current study is the first empirical investigation across the continuum from low schizotypy to schizophrenia of the tolerance to asynchronies in the processing of external (auditory) and body-related (tactile) inputs. [ABSTRACT FROM AUTHOR]

Predictive processing accounts of social perception argue that action observation is a predictive process, in which inferences about others' goals are tested against the perceptual input, inducing a subtle perceptual confirmation bias that distorts observed action kinematics toward the inferred goals. Here we test whether such biases are induced even when goals are not explicitly given but have to be derived from the unfolding action kinematics. In 2 experiments, participants briefly saw an actor reach ambiguously toward a large object and a small object, with either a whole-hand power grip or an index-finger and thumb precision grip. During its course, the hand suddenly disappeared, and participants reported its last seen position on a touch-screen. As predicted, judgments were consistently biased toward apparent action targets, such that power grips were perceived closer to large objects and precision grips closer to small objects, even if the reach kinematics were identical. Strikingly, these biases were independent of participants' explicit goal judgments. They were of equal size when action goals had to be explicitly derived in each trial (Experiment 1) or not (Experiment 2) and, across trials and across participants, explicit judgments and perceptual biases were uncorrelated. This provides evidence, for the first time, that people make online adjustments of observed actions based on the match between hand grip and object goals, distorting their perceptual representation toward implied goals. These distortions may not reflect high-level goal assumptions, but emerge from relatively low-level processing of kinematic features within the perceptual system. [ABSTRACT FROM AUTHOR]

Predictive processing accounts of social perception argue that action observation is a predictive process, in which inferences about others' goals are tested against the perceptual input, inducing a subtle perceptual confirmation bias that distorts observed action kinematics toward the inferred goals. Here we test whether such biases are induced even when goals are not explicitly given but have to be derived from the unfolding action kinematics. In 2 experiments, participants briefly saw an actor reach ambiguously toward a large object and a small object, with either a whole-hand power grip or an index-finger and thumb precision grip. During its course, the hand suddenly disappeared, and participants reported its last seen position on a touch-screen. As predicted, judgments were consistently biased toward apparent action targets, such that power grips were perceived closer to large objects and precision grips closer to small objects, even if the reach kinematics were identical. Strikingly, these biases were independent of participants' explicit goal judgments. They were of equal size when action goals had to be explicitly derived in each trial (Experiment 1) or not (Experiment 2) and, across trials and across participants, explicit judgments and perceptual biases were uncorrelated. This provides evidence, for the first time, that people make online adjustments of observed actions based on the match between hand grip and object goals, distorting their perceptual representation toward implied goals. These distortions may not reflect high-level goal assumptions, but emerge from relatively low-level processing of kinematic features within the perceptual system. [ABSTRACT FROM AUTHOR]

Patients with schizophrenia report a wide range of anomalous body experiences. According to the basic symptom model of schizophrenia, disturbances of body perception and awareness are among the most powerful predictors of the changes in the subjective experience of the self in schizophrenia. In this study we first investigated the body structural representation (BSR), a specific aspect of body awareness, and its association to basic symptoms in patients with schizophrenia. Using a finger localization task, we found that patients are significantly less accurate than healthy controls when asked to identify pairs of fingers touched by the experimenter, when the hand is hidden from view. Most importantly, patients' performance at the finger localization task was negatively associated to basic symptoms: the worse the individual accuracy, the higher the SPI-A total score. Moreover, the accuracy at the finger localization task was also negatively correlated with the malleability of the sense of body ownership: the less the individual ability to localize fingers, the stronger the rubber hand illusion. These results are in agreement with the idea that self-disorders in schizophrenia reveal a disconnectedness that can be regarded as a problem of disembodiment and traced back to abnormal body experiences. [ABSTRACT FROM AUTHOR]

Predictive processing accounts of social perception argue that action observation is a predictive process, in which inferences about others' goals are tested against the perceptual input, inducing a subtle perceptual confirmation bias that distorts observed action kinematics toward the inferred goals. Here we test whether such biases are induced even when goals are not explicitly given but have to be derived from the unfolding action kinematics. In 2 experiments, participants briefly saw an actor reach ambiguously toward a large object and a small object, with either a whole-hand power grip or an index-finger and thumb precision grip. During its course, the hand suddenly disappeared, and participants reported its last seen position on a touch-screen. As predicted, judgments were consistently biased toward apparent action targets, such that power grips were perceived closer to large objects and precision grips closer to small objects, even if the reach kinematics were identical. Strikingly, these biases were independent of participants' explicit goal judgments. They were of equal size when action goals had to be explicitly derived in each trial (Experiment 1) or not (Experiment 2) and, across trials and across participants, explicit judgments and perceptual biases were uncorrelated. This provides evidence, for the first time, that people make online adjustments of observed actions based on the match between hand grip and object goals, distorting their perceptual representation toward implied goals. These distortions may not reflect high-level goal assumptions, but emerge from relatively low-level processing of kinematic features within the perceptual system. [ABSTRACT FROM AUTHOR]

Beyond the trivial assumption that without a body we cannot gather sensory information from the environment and we cannot act upon it, our particular body, right here, right now, both enables and constrains our perception of the environment. In this review, I provide empirical support for the idea that our physical body can narrow the set of our possible interactions with the environment by shaping the way we perceive stimuli around us. I will propose that such effects are contributed by the effect of our physical body—that is, flesh and bone body—on the oscillatory dynamics of intrinsic brain activity. [ABSTRACT FROM AUTHOR]

How deep is the linkage between action and perception? Much is known about how object perception impacts on action performance, much less about how action performance affects object perception. Does action performance affect perceptual judgment on object features such as shape and orientation? Answering these questions was the aim of the present study. Participants were asked to reach and grasp a handled mug without any visual feedback before judging whether a visually presented mug was handled or not. Performing repeatedly a grasping action resulted in a perceptual categorization aftereffect as measured by a slowdown in the judgment on a handled mug. We suggest that what people are doing may impact on their perceptual judgments on the surrounding things. [ABSTRACT FROM AUTHOR]

Beyond the trivial assumption that without a body we cannot gather sensory information from the environment and we cannot act upon it, our particular body, right here, right now, both enables and constrains our perception of the environment. In this review, I provide empirical support for the idea that our physical body can narrow the set of our possible interactions with the environment by shaping the way we perceive stimuli around us. I will propose that such effects are contributed by the effect of our physical body--that is, flesh and bone body--on the oscillatory dynamics of intrinsic brain activity. [ABSTRACT FROM AUTHOR]

One of the most important ability of our brain is to integrate input from different sensory modalities to create a coherent representation of the environment. Does expectation affect such multisensory integration? In this paper, we tackled this issue by taking advantage from the crossmodal congruency effect (CCE). Participants made elevation judgments to visual target while ignoring tactile distractors. We manipulated the expectation of the tactile distractor by pairing the tactile stimulus to the index finger with a high-frequency tone and the tactile stimulus to the thumb with a low-frequency tone in 80% of the trials. In the remaining trials we delivered the tone and the visual target, but the tactile distractor was omitted (Study 1). Results fully replicated the basic crossmodal congruency effect. Strikingly, the CCE was observed, though at a lesser degree, also when the tactile distractor was not presented but merely expected. The contingencies between tones and tactile distractors were reversed in a follow-up study (Study 2), and the effect was further tested in two conceptual replications using different combinations of stimuli (Studies 5 and 6). Two control studies ruled out alternative explanations of the observed effect that would not involve a role for tactile distractors (Studies 3, 4). Two additional control studies unequivocally proved the dependency of the CCE on the spatial and temporal expectation of the distractors (Study 7, 8). An internal small-scale meta-analysis showed that the crossmodal congruency effect with predicted distractors is a robust medium size effect. Our findings reveal that multisensory integration, one of the most basic and ubiquitous mechanisms to encode external events, benefits from expectation of sensory input. [ABSTRACT FROM AUTHOR]

Viewed objects have been shown to afford suitable actions, even in the absence of any intention to act. However, little is known as to whether gaze behavior (i.e., the way we simply look at objects) is sensitive to action afforded by the seen object and how our actual motor possibilities affect this behavior. We recorded participants' eye movements during the observation of tools, graspable and ungraspable objects, while their hands were either freely resting on the table or tied behind their back. The effects of the observed object and hand posture on gaze behavior were measured by comparing the actual fixation distribution with that predicted by 2 widely supported models of visual attention, namely the Graph-Based Visual Saliency and the Adaptive Whitening Salience models. Results showed that saliency models did not accurately predict participants' fixation distributions for tools. Indeed, participants mostly fixated the action-related, functional part of the tools, regardless of its visual saliency. Critically, the restriction of the participants' action possibility led to a significant reduction of this effect and significantly improved the model prediction of the participants' gaze behavior. We suggest, first, that action-relevant object information at least in part guides gaze behavior. Second, postural information interacts with visual information to the generation of priority maps of fixation behavior. We support the view that the kind of information we access from the environment is constrained by our readiness to act. [ABSTRACT FROM AUTHOR]

Synchronous, but not asynchronous, multisensory stimulation has been successfully employed to manipulate the experience of body ownership, as in the case of the rubber hand illusion. Hence, it has been assumed that the rubber hand illusion is bound by the same temporal rules as in multisensory integration. However, empirical evidence of a direct link between the temporal limits on the rubber hand illusion and those on multisensory integration is still lacking. Here we provide the first comprehensive evidence that individual susceptibility to the rubber hand illusion depends upon the individual temporal resolution in multisensory perception, as indexed by the temporal binding window. In particular, in two studies we showed that the degree of temporal asynchrony necessary to prevent the induction of the rubber hand illusion depends upon the individuals' sensitivity to perceiving asynchrony during visuo-tactile stimulation. That is, the larger the temporal binding window, as inferred from a simultaneity judgment task, the higher the level of asynchrony tolerated in the rubber hand illusion. Our results suggest that current neurocognitive models of body ownership can be enriched with a temporal dimension. Moreover, our results suggest that the different aspects of body ownership operate over different time scales. [ABSTRACT FROM AUTHOR]

We live in a dynamic environment, constantly confronted with approaching objects that we may either avoid or be forced to address. A multisensory and sensorimotor interface, the peripersonal space (PPS), mediates every physical interaction between our body and the environment. Behavioral investigations show high variability in the extension of PPS across individuals, but there is a lack of evidence on the neural underpinnings of these large individual differences. Here, we used approaching auditory stimuli and fMRI to capture the individual boundary of PPS and examine its neural underpinnings. Precisely, we tested the hypothesis that intertrial variability (ITV) in brain regions coding PPS predicts individual differences of its boundary at the behavioral level. Selectively in the premotor cortex, we found that ITV, rather than trial-averaged amplitude, of BOLD responses to far rather than near dynamic stimuli predicts the individual extension of PPS. Our results provide the first empirical support for the relevance of ITV of brain responses for individual differences in human behavior. [ABSTRACT FROM AUTHOR]

It is widely accepted that the representation of the body is not fixed and immutable, but rather flexible and constantly updated based on a continuous stream of multisensory information. This mechanism can be very useful to adapt to several situations, but it would not be adaptive if the body representation was too malleable or if it wasn't capable of restoring its integrity after a transient modification. Here we used the Rubber Hand Illusion (RHI) to investigate how quickly the body representation can be modified. Previous studies have investigated the timing of the onset and offset of the illusion, however, they did not assess a fine temporal resolution. Here, we used a potentiometer to record a moment-by-moment rating of the feeling of owning the RH for two minutes during the visuo-tactile stimulation and two minutes following the stimulation. Our results suggest that the feeling of Ownership is already established during the first 19 s of stimulation then it continues to grow, but at a much slower pace. The feeling of Ownership disappears within 66 s from the end of the stimulation. This work sheds new light on the temporal dynamics of the RHI and the malleability of the body self-consciousness. [ABSTRACT FROM AUTHOR]

Background: As social animals we share the space with other people. It is known that perceived extension of the peripersonal space (the reaching space) is affected by the implicit representation of our own and other's action potentialities. Our issue concerns whether the co-presence of a body in the scene influences our extrapersonal space (beyond reaching distance) categorization. Methodology/Principal Findings: We investigated, through 3D virtual scenes of a realistic environment, whether egocentric spatial categorization can be influenced by the presence of another human body (Exp. 1) and whether the effect is due to her action potentialities or simply to her human-like morphology (Exp. 2). Subjects were asked to judge the location ("Near" or "Far") of a target object located at different distances from their egocentric perspective. In Exp. 1, the judgment was given either in presence of a virtual avatar (Self-with-Other), or a non-corporeal object (Self-with-Object) or nothing (Self). In Exp. 2, the Self condition was replaced by a Self-with-Dummy condition, in which an inanimate body (a wooden dummy) was present. Mean Judgment Transition Thresholds (JTTs) were calculated for each subject in each experimental condition. Self-with-Other condition induced a significant extension of the space judged as “Near” as compared to both the Self-with-Object condition and the Self condition. Such extension was observed also in Exp. 2 in the Self-with-Dummy condition. Results suggest that the presence of others impacts on our perception of extrapersonal space. This effect holds also when the other is a human-like wooden dummy, suggesting that structural and morphological shapes resembling human bodies are sufficient conditions for the effect to occur. Conclusions: The observed extension of the portion of space judged as near could represent a wider portion of “accessible” space, thus an advantage in the struggle to survive in presence of other potential competing individuals. [ABSTRACT FROM AUTHOR]

Background/Aims: Several components of social cognition are compromised in schizophrenia (SCZ) from the early stage of the illness. In this study we first investigated whether mirror neuron-driven embodied simulation (mnES) is altered in first-episode SCZ. Second, we tested whether emotional cues impact on the mnES in SCZ patients. Methods: Twenty-two SCZ patients and 22 healthy controls (HCs) observed goal-related actions in either a neutral or emotional context during functional magnetic resonance imaging scanning. Results: Observation of neutral action elicited a lower activity in the frontoparietal network in SCZ patients, as compared to HCs. Particularly, activation in the left inferior parietal lobule in response to the same condition negatively correlated with patients' self-experience disturbances. Moreover, observation of an action performed by an angry agent produced poorer neural activity in the right anterior insula in SCZ patients as compared to HCs. This difference was mostly due to the negative β-values shown by SCZ patients, which positively correlated with their empathy scores. No differences were found contingent upon the observation of an action performed by a happy agent. Conclusion: Our results show that emotional cues allow SCZ patients to partially recover mnES. However, their understanding of the emotional components of the actions of others will likely remain deficient. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The role of active tool use in the remapping of space in hemispatial neglect patients has been extensively investigated. To date, however, there is no evidence that observing tool use can play a role in the remapping of space in hemispatial neglect patients. In this study, a patient with a severe hemispatial neglect in near but not far space and twelve healthy controls were asked to bisect near and far lines using a laser pen. The task was performed both before and immediately after sessions in which they merely observed the experimenter bisecting near and far lines with a stick. During the observation session, participants were either holding an identical stick or empty-handed. Results, in both the neglect patient and healthy controls, showed that observing the experimenter bisecting line while holding the same tool, produces a remapping of the far space into the near space. This result was particularly evident in the neglect patient where observing line-bisection task extended the spatial deficit from the near to the far space. Our results provide new empirical support to the idea that the space around us is not mapped in merely metrical terms, rather it seems to be deeply impacted by both action observation and execution. [ABSTRACT FROM AUTHOR]

Perceiving a body is a phenomenal experience completely different from experiencing a body as one's own body. Visual presentation of bodies or body parts recruits several occipitotemporal regions in the brain. Are these activations sufficient in order to change the phenomenal status of a body in one's own body? In this paper, I will review consolidated experimental evidence showing that the feeling of owning a body is not limited to the vision of a body, rather it is the result of a complex interaction between interoception, exteroception, and pre-existing body templates. To illustrate this complex interplay, I will take advantage of the so-called bodily illusions, referring to controlled illusory generation of unusual bodily feeling. These feelings include having a supernumerary limb, or lacking an arm, or feeling like you do not really have a body, or feeling that you do not really control a certain part of your body, or that your body is not really yours. In the last 15 years more than 150 empirical studies on body illusions have been published (Source: Pubmed, June 2014). These studies, using different technologies, are largely responsible for contributed our current understanding of bodily self-consciousness. [ABSTRACT FROM AUTHOR]

When viewing object-related hand actions people make proactive eye movements of the same kind as those made when performing such actions. Why is this so? It has been suggested that proactive gaze when viewing a given hand action depends on the recruitment of motor areas such as the ventral premotor (PMv) cortex that would be involved in the execution of that action. However, direct evidence for a distinctive role of the PMv cortex in driving gaze behavior is still lacking. We recorded eye moments while viewing hand actions before and immediately after delivering repetitive transcranial magnetic stimulation (rTMS) over the left PMv and the posterior part of the left superior temporal sulcus, which is known to be involved in high-order visual action processing. Our results showed that rTMS-induced effects were selective with respect to the viewed actions following the virtual lesion of the left PMv only. This, for the first time, provides direct evidence that the PMv cortex might selectively contribute to driving the viewer’s gaze to the action’s target. When people view another’s action, their eyes may be driven by motor processes similar to those they would need to perform the action themselves. [ABSTRACT FROM AUTHOR]

Abstract: Schizophrenic patients may report unusual perception of their own body. Studies using the rubber hand illusion (RHI) proposed that they exhibit a distorted sense of body ownership. However, since the RHI is mostly achieved with the contribution of visuo-tactile integration, the stronger RHI observed in schizophrenic patients could reflect either a general increase of the response to multisensory stimuli or a larger influence of visual cues on the tactile sensory experience. The purpose of the present study is to investigate patients' perception of their own body by means of a behavioral paradigm that measures their proneness to the RHI without relying on multisensory integration occurring during actual experience of touch. In a previous study we demonstrated in healthy participants that expectation of touch experience arising at the sight of a human hand approaching a rubber hand is enough to induce a sense of ownership over the same hand. Here we take advantage of the same paradigm to investigate body ownership in schizophrenia. Patients observed the experimenter's hand while approaching – without touching – either a rubber hand or a piece of wood placed in front of them. The seen object could be either aligned to participant's hand or rotated by 180°. Phenomenology of the illusion revealed that schizophrenic patients exhibited sense of ownership over the rubber hand, but more weakly than healthy controls. The present study sheds new light on the experience of body ownership in schizophrenic patients, corroborating the notion that alterations of bodily self-awareness play an important role in schizophrenia. [Copyright &y& Elsevier]

Recent evidence indicates that we experience manipulable objects as graspable, provided that they fall within our reaching space. Nevertheless, such evidence comes from studies using virtual objects that have poor ecological validity. Here, we used a spatial alignment effect paradigm and systematically examined this effect when a real handled object was presented at four different distances, namely near-reaching space, actual-reaching space, perceived-reaching space, and non-reaching space. Participants responded with either the right or the left hand as soon as the real object, a mug with the handle oriented toward the left or right, was presented. We found spatial compatibility effect only when the object was presented in the near-reaching and actual-reaching spaces. Results suggest that the activation of the potential actions to perform with objects is modulated by object accessibility. They also suggest that accessibility is exclusively linked to the actual rather than the estimated reaching ability of the perceiver. Results are discussed within the theoretical framework of embodied cognition. [ABSTRACT FROM AUTHOR]

• Multisensory integration, body representation, and pain are often linked. • Neural changes in SCI may influence multisensory integration and body representation. • Neuropathic pain in SCI may be partially related to deficits in multisensory body representation. • Multisensory integration and body representation in SCI are novel fields of study. • Multisensory trainings may be beneficial to prevent maladaptive brain reorganization. In this review we focus on maladaptive brain reorganization after spinal cord injury (SCI), including the development of neuropathic pain, and its relationship with impairments in body representation and multisensory integration. We will discuss the implications of altered sensorimotor interactions after SCI with and without neuropathic pain and possible deficits in multisensory integration and body representation. Within this framework we will examine published research findings focused on the use of bodily illusions to manipulate multisensory body representation to induce analgesic effects in heterogeneous chronic pain populations and in SCI-related neuropathic pain. We propose that the development and intensification of neuropathic pain after SCI is partly dependent on brain reorganization associated with dysfunctional multisensory integration processes and distorted body representation. We conclude this review by suggesting future research avenues that may lead to a better understanding of the complex mechanisms underlying the sense of the body after SCI, with a focus on cortical changes. [ABSTRACT FROM AUTHOR]

Humans are thought to be able to form shared representations, considered a keystone of social cognition. However, whether and to what extent such representations are social in nature is still open for debate. In the present study, we address the question of whether action co-representation can be modulated by social attitudes, such as judgments about one's own social status. Two groups of participants performed an Interactive Simon task after the experimental induction of a feeling of social inclusion or exclusion (ostracism) by means of a virtual ball tossing game. Results showed a compatibility effect in included, but not in excluded participants. This indicates that judgments about one's own social status modulate action co-representation. We suggest that this modulation may occur by way of a redirection of one's attentional focus away from others when one experiences social exclusion. This is a far-reaching issue given the increasing need for integration in modern society. Indeed, if integration fails, modern society fails also. [ABSTRACT FROM AUTHOR]

In order to understand the so-called "social brain," we need to monitor social interactions in face-to-face paradigms. Near-infrared spectroscopy (NIRS) is a promising technique to achieve this goal. We investigate the neuronal underpinnings of sharing a task in a proper social context. We record cortical activity by means of NIRS, while participants perform a joint Simon task. Different from other hemodynamic techniques, NIRS allows us to have both participants sit comfortably close to each other in a realistic and ecological environment. We found higher activation in the sensorimotor cortex while processing compatible trials as compared to incompatible ones referring to one's own action alternative. Strikingly, when the participant was not responding because it was the turn of the other member of the pair, the inferior parietal was activated. This study provides twofold findings: first, they suggest that the joint Simon effect relies more on shared attentional mechanisms than a proper mapping of the other's motor response. Second, they highlight the invaluable contribution NIRS can afford to social neuroscience in order to preserve ecological and naturalistic settings. [ABSTRACT FROM AUTHOR]

Abstract: Previous studies showed that people proactively gaze at the target of another''s action by taking advantage of their own motor representation of that action. But just how selectively is one''s own motor representation implicated in another''s action processing? If people observe another''s action while performing a compatible or an incompatible action themselves, will this impact on their gaze behaviour? We recorded proactive eye movements while participants observed an actor grasping small or large objects. The participants'' right hand either freely rested on the table or held with a suitable grip a large or a small object, respectively. Proactivity of gaze behaviour significantly decreased when participants observed the actor reaching her target with a grip that was incompatible with respect to that used by them to hold the object in their own hand. This indicates that effective observation of action may depend on what one is actually doing, being actions observed best when the suitable motor representations may be readily recruited. [Copyright &y& Elsevier]

When witnessing another's action, people recruit the same motor resources that enable them to efficiently perform that action, thus gazing at its target well before the agent's hand. But just to what extent does this recruitment help people in grabbing another's action target? If the latter seems to be out of the agent's reach, will this impact on people's gaze behaviour? We recorded proactive eye movements while participants witnessed someone else trying to reach for and grasp objects located either within or outside his reach. Proactivity of gaze was impaired when the targets were just out of the agent's reach. This effect is likely to be due to an interpersonal bodily space representation that allows one to map another's reaching space, thus prompting proactive eye movements towards the target just in case the agent is in the position to act upon it. [ABSTRACT FROM PUBLISHER]

Abstract: Previous evidence has shown that active tool-use remaps agents’ reaching space with far objects being perceived as reachable and graspable. To date, however, there is no evidence that tool-use observation might also be effective in reaching space remapping. The present six experiments show that not only performing but also observing tool actions may extend the representation of reaching space, useful for grasping objects. In addition, like active tool-use, tool-use observation also impacts on visual distance judgment. Interestingly, these effects only occurred when observers shared the same action potentialities with the agent, i.e., while passively holding a tool compatible with the goal and the spatial range of the observed action. The present findings demonstrate that observing someone else acting with a tool may actually shape the way we map the objects and the space around us, suggesting that such a mapping could provide us with a keystone for coordinating and integrating our actions with those of others. [Copyright &y& Elsevier]

Abstract: Although vision is the primary sensory modality that humans and other primates use to identify objects in the environment, we can recognize crucial object features (e.g., shape, size) using the somatic modality. Previous studies have shown that the occipito-temporal areas dedicated to the visual processing of object forms, faces and bodies also show category-selective responses when the preferred stimuli are haptically explored out of view. Visual processing of human bodies engages specific areas in lateral (extrastriate body area, EBA) and medial (fusiform body area, FBA) occipito-temporal cortex. This study aimed at exploring the relative involvement of EBA and FBA in the haptic exploration of body parts. During fMRI scanning, participants were asked to haptically explore either real-size fake body parts or objects. We found a selective activation of right and left EBA, but not of right FBA, while participants haptically explored body parts as compared to real objects. This suggests that EBA may integrate visual body representations with somatosensory information regarding body parts and form a multimodal representation of the body. Furthermore, both left and right EBA showed a comparable level of body selectivity during haptic perception and visual imagery. However, right but not left EBA was more activated during haptic exploration than visual imagery of body parts, ruling out that the response to haptic body exploration was entirely due to the use of visual imagery. Overall, the results point to the existence of different multimodal body representations in the occipito-temporal cortex which are activated during perception and imagery of human body parts. [Copyright &y& Elsevier]

In the present study, we investigated, using language, which motor information is automatically activated by observing 3-D objects (i.e., manipulation vs. function) and whether this information is modulated by the objects' location in space. Participants were shown 3-D pictures of objects located in peripersonal versus extrapersonal space. Immediately after, they were presented with function, manipulation, or observation verbs (e.g., 'to drink,' 'to grasp,' 'to look at') and were required to judge whether the verb was compatible with the presented object. We found that participants were slower with observation verbs than with manipulation and function verbs. With both function and manipulation verbs, participants were faster when objects were presented in reachable space. Interestingly, the fastest response times were recorded when participants read function verbs while objects were presented in the accessible space. Results suggest that artifacts are first conceived in terms of affordances linked to manipulation and use, and that affordances are differently activated, depending on context. [ABSTRACT FROM AUTHOR]

Abstract: Several studies on humans have shown a recruitment of the sensory-motor system in the perception of action-related visual and verbal material, suggesting that actions are represented through sensory-motor processes. To date, these studies have not disentangled whether such a recruitment is epiphenomenal or necessary to action representation. Here we took advantage of repetition priming as a tool to investigate the cognitive representation of actions, and systematically looked whether a concurrent motor or verbal task had a detrimental effect on this representation. In a first experiment participants discriminated images depicting meaningless and meaningful actions, while performing either a concurrent sensory-motor or an articulatory suppression task. Images were classified as depicting a repeated or a new action, relative to the previous image in the trial series. We found a facilitation by repetition priming, that was unaffected by the articulatory task but was completely abolished by the sensory-motor task. In a second experiment, we investigated whether the sensory-motor system is also causally involved in processing action-related verbs. In this experiment actions were presented as written infinitive verbs rather than as images. The facilitation by repetition priming was again unaffected by the concurrent articulatory task, while the sensory-motor concurrent task, although reducing the facilitation, did not abolish it. Our data provide evidence that the sensory-motor system is differentially involved during visual processing of actions and during processing of action-related verbs. Results are discussed within the theoretical frame of embodied cognition. [Copyright &y& Elsevier]

To date, mutual interaction between action and perception has been investigated mainly by focusing on single individuals. However, we perceive affording objects and acts upon them in a surrounding world inhabited by other perceiving and acting bodies. Thus, the issue arises as to whether our action-oriented object perception might be modulated by the presence of another potential actor. To tackle this issue we used the spatial alignment effect paradigm and systematically examined this effect when a visually presented handled object was located close either to the perceiver or to another individual (a virtual avatar). We found that the spatial alignment effect occurred whenever the object was presented within the reaching space of a potential actor, regardless of whether it was the participant's own or the other's reaching space. These findings show that objects may afford a suitable motor act when they are ready not only to our own hand but also, and most importantly, to the other's hand. Our proposal is that this effect is likely to be due to a mapping of our own and the other's reaching space and we posit that such mapping could play a critical role in joining our own and the other's action. [ABSTRACT FROM AUTHOR]

Background: Acute myocarditis may mimic myocardial infarction, since affected patients complain of "typical" chest pain, the ECG changes are identical to those observed in acute coronary syndromes, and serum markers are increased. We describe a case series of presumptive myocarditis with ST segment elevation on admission ECG. Methods and Results: From 1998 to 2009, 21 patients (20 males; age 17-42 years) were admitted with chest pain, persistent ST segment elevation, serum enzyme and troponine release. All but one patients had fever and flu-like symptoms prior to admission. No abnormal Q wave appeared in any ECG tracing, and angiography did not show significant coronary artery disease. Patients remained asymptomatic at long term follow-up, except 2 who experienced a late relapse, with the same clinical, electrocardiographic and serum findings as in the first clinical presentation. Conclusion: Presumptive myocarditis of possible viral origin characterized by ST elevation mimicking myocardial infarction, good short term prognosis and some risk for recurrence is relatively frequent in young males and appears as a distinct clinical condition. [ABSTRACT FROM AUTHOR]

series of experiments provide evidence that affordances rely not only on the mutual appropriateness of the features of an object and the abilities of an individual, but also on the fact that those features fall within her own reachable space, thus being really ready- to- her- own- hand. We used a spatial alignment effect paradigm and systematically examined this effect when the visually presented object was located either within or outside the peripersonal space of the participants, both from a metric (Experiment 1) and from a functional point of view (Experiment 2). We found that objectual features evoke actions only when the object is presented within the portion of the peripersonal space that is effectively reachable by the participants. Experiments 3 and 4 ruled out that our results could be merely accounted for by differences in the visual salience of the presented objects. Our data suggest that the power of an object to automatically trigger an action is strictly linked to the effective possibility that an individual has to interact with it. [ABSTRACT FROM AUTHOR]

Abstract: We constantly feel, see and move our body, and have no doubt that it is our own. The brain possesses a distinction between the body and the objects in the outside world. This distinction may be based on a process that monitors whether sensations, events and objects should be attributed to one''s body or not. We controlled whether an external object was represented as part of the body or not, by experimentally inducing a bodily illusion using correlated visual and tactile stimulation. We then studied the role of right temporo-parietal junction (rTPJ) in the processing of multisensory events that may or may not be attributed to one''s body. Disruption of rTPJ using transcranial magnetic stimulation (TMS) made the distinction between what may or may not be part of one''s body on the basis of multisensory evidence more ambiguous, suggesting that the rTPJ is actively involved in maintaining a coherent sense of one''s body, distinct from external, non-corporeal, objects. [Copyright &y& Elsevier]

Neuroimaging studies report that the experience of observing or imagining the pain of others is mapped on a set of neural structures that largely overlap those called into play during the personal experience of pain (the so-called pain matrix). Empathy for pain is a multifaceted process that may be triggered by higher-order variables (such as imagination of others’ suffering) or by the direct vision of painful situations. Most functional magnetic resonance imaging studies indicate that the empathic mapping of others’ pain may rely on the affective and not on the sensorimotor division of the pain matrix. However, as empathy for pain is a complex, multifarious process, it is possible that different brain regions, even beyond the classic pain matrix, may be called into action in different circumstances. By using functional magnetic resonance imaging we explored the neural activity induced by needles deeply penetrating a hand or a non-corporeal object. We found that observation of pain in others brought about activation in the middle cingulate, left premotor and left and right supramarginal regions. This pattern of neural activity indicates that the direct vision of strong painful stimuli delivered to others activates neural regions in the onlooker’s brain specifically concerned with the resonant, interindividual sharing of basic sensorimotor reactivity to pain. We also found that bilateral posterior parietal and temporo-occipital regions were activated during observation of painful stimuli delivered to the body of others as well as to non-body stimuli. Therefore, our study expands current knowledge on the neural reactivity to potentially dangerous stimuli delivered in the peripersonal space. [ABSTRACT FROM AUTHOR]

Simulation mechanisms are thought to play an important role in action recognition. On this view, actions are represented through the re-enactment of the observed action. Mirror neurons are thought to be the neuronal counterpart of such a process, and code actions at a rather abstract level, often generalizing across sensory modalities and effectors. In humans, attention has been focussed on the somatotopic, effector dependent representation of observed actions in the mirror system. In this series of behavioural studies, we used incidental repetition priming to determine to which degree the cognitive representation of observed actions relies on effector- and target-dependent representations. Participants were presented with images depicting meaningless or meaningful actions and pressed a button only when presented with a meaningful action. Images were classified as depicting a repeated or new action, relative to the previous image in the trial series. In the first experiment, we demonstrate a priming effect based on the repetition of an action, performed by the same effector over the same target object. In the second experiment, we demonstrate that this facilitation holds even when the same action is performed over a different target object. Finally, in the third experiment we show that the action priming effect holds even when the same action is accomplished with different effectors. These results suggest the existence of a cognitive representation of actions, automatically activated during observation, which is abstract enough to generalize across different targets for that action and different effectors performing that action. [ABSTRACT FROM AUTHOR]

Abstract: When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed ‘Rubber Hand Illusion’ (RHI). We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the two hands. We created the mismatch either by adjusting stimulation or posture of the subject’s hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject’s hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject’s hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject’s hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject’s hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual–tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is ‘me’ is interpreted with respect to a prior mental body representation. [Copyright &y& Elsevier]

The influence of ipsilesional tactile and visual stimuli on the ability to detect contralesional tactile stimuli was investigated in eight right brain damaged patients (RBD) with tactile extinction and in eight healthy subjects by delivering a series of single and double stimuli. Double stimuli were unimodal (tactile or visual) or cross-modal (tactile and visual) and could be delivered simultaneously or sequentially at three possible intervals (65, 125, 305 ms). In sequential double trials, left-sided stimuli preceded or followed right-sided stimuli. Subjects were asked to verbally report number (1 or 2), side (left or right) and modality (tactile, visual, visuo-tactile). Control subjects were highly accurate in detecting single and double stimuli. RBD patients detected all right-sided stimuli and left single visual or tactile stimuli with high accuracy; however, they omitted left-sided tactile stimuli in a high proportion of double trials due to the presence of tactile extinction.Omissions of left-sided tactile stimuli were minimal at the longest SOA. Moreover, at 0 and 65 ms SOA omissions were significantly higher in unimodal than in cross-modal combinations. This figure indicates that detection of contralesional tactile stimuli is modulated over time both uni- and cross-modally. [Copyright &y& Elsevier]

The peripersonal space (PPS) is a multisensory and sensorimotor interface between our body and the environment. The location of PPS boundary is not fixed. Rather, it adapts to the environmental context and differs greatly across individuals. Recent studies have started to unveil the neural correlates of individual differences in PPS extension; however, this picture is not clear yet. Here, we used approaching auditory stimuli and magnetoencephalography to capture the individual boundary of PPS and examine its neural underpinnings. In particular, building upon previous studies from our own group, we investigated the possible contribution of an intrinsic feature of the brain, that is the "resting state" functional connectivity, to the individual differences in PPS extension and the frequency specificity of this contribution. Specifically, we focused on the activity synchronized to the premotor cortex, where multisensory neurons encoding PPS have been described. Results showed that the stronger the connectivity between left premotor cortex (lPM) and a set of fronto-parietal, sensorimotor regions in the right and left hemisphere, the wider the extension of the PPS. Strikingly, such a correlation was observed only in the beta-frequency band. Overall, our results suggest that the individual extension of the PPS is coded in spatially- and spectrally-specific resting state functional links. • Resting state functional connectivity contributes to individual differences in PPS extension. • Wider PPS is linked to stronger synchronization between lPM and bilateral sensorimotor cortices. • MEG synchronization patterns relevant to individual PPS are specifically observed in the beta-frequency band. • Our results support the notion of PPS extension as a "trait-like" feature of the individual. [ABSTRACT FROM AUTHOR]

Multisensory stimuli are integrated over a delimited window of temporal asynchronies. This window is highly variable across individuals, but the origins of this variability are still not clear. We hypothesized that immune system functioning could partially account for this variability. In two experiments, we investigated the relationship between key aspects of multisensory integration in allergic participants and healthy controls. First, we tested the temporal constraint of multisensory integration, as measured by the temporal binding window. Second, we tested multisensory body representation, as indexed by the Rubber Hand Illusion (RHI). Results showed that allergic participants have a narrower temporal binding window and are less susceptible to the RHI than healthy controls. Overall, we provide evidence linking multisensory integration processes and the activity of the immune system. The present findings are discussed within the context of the effect of immune molecules on the brain mechanisms enabling multisensory integration and multisensory body representation. [ABSTRACT FROM AUTHOR]

Acute myocarditis may mimic an infarction. Aim is to describe a case series of peculiar myocarditis. From 1997 to 2003, 11 male patients (age 17–39 years) were admitted with diagnosis of acute myocardial infarction, localized ST segment elevation and minimal enzyme release. Ten patients had fever in the 3 days prior to admission. Eight patients underwent coronary angiography showing normal coronary arteries. All remained asymptomatic at long term follow-up. In conclusion, myocarditis with ST elevation myocardial infarction presentation is an acute benign syndrome especially frequent in young males. [Copyright &y& Elsevier]

Bodily boundaries are computed by integrating multisensory bodily signals and can be experimentally manipulated using bodily illusions. Research on tool use demonstrates that tools alter body representations motorically to account for changes in a user’s action repertoire. The present experiment sought to unify perceptual and motoric accounts of tool embodiment using a modified Rubber Hand Illusion (RHI) that also addressed the skill and practice aspects of the tool use literature. In Experiment 1, synchronous multisensory stimulation induced perceptual embodiment of a tool, chopsticks. The embodiment of chopsticks was stronger for more skilled participants, and if the illusion was preceded by tool use. In Experiment 2, the illusion was not elicited with a different type of tool, a teacup, showing that not all objects can be incorporated. This experiment helps to clarify the role of perceptual and motoric embodiment and suggests future avenues for research into tools embodiment using this method. [ABSTRACT FROM AUTHOR]

Action and object are deeply linked to each other. Not only can viewing an object influence an ongoing action, but motor representations of action can also influence visual categorization of objects. It is tempting to assume that this influence is effector-specific. However, there is indirect evidence suggesting that this influence may be related to the action goal and not just to the effector involved in achieving it. This paper aimed, for the first time, to tackle this issue directly. Participants were asked to categorize different objects in terms of the effector (e.g. hand or foot) typically used to act upon them. The task was delivered before and after a training session in which participants were instructed either just to press a pedal with their foot or to perform the same foot action with the goal of guiding an avatar's hand to grasp a small ball. Results showed that pressing a pedal to grasp a ball influenced how participants correctly identified graspable objects as hand-related ones, making their responses more uncertain than before the training. Just pressing a pedal did not have any similar effect. This is evidence that the influence of action on object categorization can be goal-related rather than effector-specific. [ABSTRACT FROM AUTHOR]

The ability to predict the outcome of other beings' actions confers significant adaptive advantages. Experiments have assessed that human action observation can use multiple information sources, but it is currently unknown how they are integrated and how conflicts between them are resolved. To address this issue, we designed an action observation paradigm requiring the integration of multiple, potentially conflicting sources of evidence about the action target: the actor's gaze direction, hand preshape, and arm trajectory, and their availability and relative uncertainty in time. In two experiments, we analyzed participants' action prediction ability by using eye tracking and behavioral measures. The results show that the information provided by the actor's gaze affected participants' explicit predictions. However, results also show that gaze information was disregarded as soon as information on the actor's hand preshape was available, and this latter information source had widespread effects on participants' prediction ability. Furthermore, as the action unfolded in time, participants relied increasingly more on the arm movement source, showing sensitivity to its increasing informativeness. Therefore, the results suggest that the brain forms a robust estimate of the actor's motor intention by integrating multiple sources of information. However, when informative motor cues such as a preshaped hand with a given grip are available and might help in selecting action targets, people tend to capitalize on such motor cues, thus turning out to be more accurate and fast in inferring the object to be manipulated by the other's hand. [ABSTRACT FROM AUTHOR]

Pointing is a communicative gesture, commonly used for expressing two main intentions: imperative, to obtain a desired object/action from the other, or declarative, to share attention/interest about a referent with the other. Previous neuroimaging research on adults examined pointing almost exclusively as a reaching-like motor act rather than as a communicative gesture. Here, we used fMRI to record brain activity while 16 participants produced either imperative or declarative pointing gestures within a communicative context. A network of regions (the bilateral ventral premotor cortex, anterior midcingulate cortex, middle insula and the right preSMA) showed a preference for the production of declarative pointing as opposed to imperative pointing. The right preSMA also preferred declarative intention during pointing observation. Instead, independently from the intention, the right pMTG was more active during pointing observation than production. In the bilateral posterior parietal reach region we also observed a side (contra > ipsi) effect when the intention was imperative, regardless of the subject's role in the communication. Based on these results, we propose that pointing with declarative intention recruits a network of regions associated with will, motivation, emotional/affective expression and intersubjectivity, whereas pointing with imperative intention recruits regions associated with reaching. The proposal is consistent with the developmental hypothesis that declarative pointing reflects social cognitive abilities more than imperative pointing and establishes a stimulating link for future interdisciplinary research. [ABSTRACT FROM AUTHOR]

Several neuroimaging studies reported that a common set of regions is recruited during action observation and execution and it has been proposed that the modulation of the μ rhythm, in terms of oscillations in the alpha and beta bands might represent the electrophysiological correlate of the underlying brain mechanisms. However, the specific functional role of these bands within the μ rhythm is still unclear. Here, we used magnetoencephalography (MEG) to analyze the spectral and temporal properties of the alpha and beta bands in healthy subjects during an action observation and execution task. We associated the modulation of the alpha and beta power to a broad action observation network comprising several parieto-frontal areas previously detected in fMRI studies. Of note, we observed a dissociation between alpha and beta bands with a slow-down of beta oscillations compared to alpha during action observation. We hypothesize that this segregation is linked to a different sequence of information processing and we interpret these modulations in terms of internal models (forward and inverse). In fact, these processes showed opposite temporal sequences of occurrence: anterior–posterior during action (both in alpha and beta bands) and roughly posterior–anterior during observation (in the alpha band). The observed differentiation between alpha and beta suggests that these two bands might pursue different functions in the action observation and execution processes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Body ownership and self-location are distinct components of bodily-self consciousness. [•] Body ownership and self-location are implemented in distinct neural substrates. [•] Body ownership and self-location can be selectively affected in patients with altered body perception. [•] Body ownership and self-location can be selectively manipulated by multisensory body-related illusions. [Copyright &y& Elsevier]

It has been suggested that our perception of the internal milieu, or the body's internal state, is shaped by our beliefs and previous knowledge about the body's expected state, rather than being solely based on actual interoceptive experiences. This study investigated whether heartbeat perception could be illusorily distorted towards prior subjective beliefs, such that threat expectations suffice to induce a misperception of heartbeat frequency. Participants were instructed to focus on their cardiac activity and report their heartbeat, either tapping along to it (Experiment 1) or silently counting (Experiment 2) while ECG was recorded. While completing this task, different cues provided valid predictive information about the intensity of an upcoming cutaneous stimulation (high- vs. low- pain). Results showed that participants expected a heart rate increase over the anticipation of high- vs. low-pain stimuli and that this belief was perceptually instantiated, as suggested by their interoceptive reports. Importantly, the perceived increase was not mirrored by the real heart rate. Perceptual modulations were absent when participants executed the same task but with an exteroceptive stimulus (Experiment 3). The findings reveal, for the first time, an interoceptive illusion of increased heartbeats elicited by threat expectancy and shed new light on interoceptive processes through the lenses of Bayesian predictive processes, providing tantalizing insights into how such illusory phenomena may intersect with the recognition and regulation of people's internal states. • Anticipation of pain elicits an illusory increase in perceived heartbeats. • Threat expectancy does not influence actual heart rate. • Anticipated threat shapes interoceptive perception, not exteroceptive perception. • Threat-induced interoceptive illusions align with Bayesian predictive processes. • Interoceptive illusions contribute to our understanding of psychological conditions. [ABSTRACT FROM AUTHOR]