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Neurological evidence has shown that brain damages canselectively impair the ability to discriminate between objectsbelonging to others and those that we feel are our own. Despitethe ubiquity and relevance of this sense of object ownership forour life, the underlying cognitive mechanisms are still poorlyunderstood. Here we ask whether psychological ownership ofan object can be based on its incorporation in one’s body image.To explore this possibility with healthy participants, weemployed a modified version of the rubber hand illusion inwhich both the participant and the rubber hand wore a ring. Weused the self-prioritization effect in a perceptual matching taskas an indirect measure of the sense of (dis)ownership overobjects. Results indicate that undermining the bodily self hascascade effects on the representation of owned objects, at leastfor those associated with the body for a long time.

Many studies have reported that bottom-up multisensory integration of visual, tactile, and proprioceptive information can distort our sense of body-ownership, producing rubber hand illusion (RHI). There is less evidence about when and how the body-ownership is distorted in the brain during RHI. To examine whether this illusion effect occurs preattentively at an early stage of processing, we monitored the visual mismatch negativity (vMMN) component (the index of automatic deviant detection) and N2 (the index for conflict monitoring). Participants first performed an RHI elicitation task in a synchronous or asynchronous setting and then finished a passive visual oddball task in which the deviant stimuli were unrelated to the explicit task. A significant interaction between Deviancy (deviant hand vs. standard hand) and Group (synchronous vs. asynchronous) was found. The asynchronous group showed clear mismatch effects in both vMMN and N2, while the synchronous group had such effect only in N2. The results indicate that after the elicitation of RHI bottom-up integration could be retrieved at the early stage of sensory processing before top-down processing, providing evidence for the priority of the bottom-up processes after the generation of RHI and revealing the mechanism of how the body-ownership is unconsciously distorted in the brain.

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The ability of virtual reality (VR) to recreate controlled, immersive, and interactive environments that provide intensive and customized exercises has motivated its therapeutic use after stroke. Interaction and bodily presence in VR-based interventions is usually mediated through virtual selves, which synchronously represent body movements or responses to events on external input devices. Embodied self-representations in the virtual world not only provide an anchor for visuomotor tasks, but their morphologies can have behavioral implications. While research has focused on the underlying subjective mechanisms of exposure to VR on healthy individuals, the transference of these findings to individuals with stroke is not evident and remains unexplored, which could affect the experience and, ultimately, the clinical effectiveness of neurorehabilitation interventions. This study determined and compared the sense of embodiment and presence elicited by a virtual environment under different perspectives and levels of immersion in healthy subjects and individuals with stroke. Forty-six healthy subjects and 32 individuals with stroke embodied a gender-matched neutral avatar in a virtual environment that was displayed in a first-person perspective with a head-mounted display and in a third-person perspective with a screen, and the participants were asked to interact in a virtual task for 10 min under each condition in counterbalanced order, and to complete two questionnaires about the sense of embodiment and presence experienced during the interaction. The sense of body-ownership, self-location, and presence were more vividly experienced in a first-person than in a third-person perspective by both healthy subjects (p < 0.001, ηp2 = 0.212; p = 0.005, ηp2 = 0.101; p = 0.001, ηp2 = 0.401, respectively) and individuals with stroke (p = 0.019, ηp2 = 0.070; p = 0.001, ηp2 = 0.135; p = 0.014, ηp2 = 0.077, respectively). In contrast, no agency perspective-related differences were found in any group. All measures were consistently higher for healthy controls than for individuals with stroke, but differences between groups only reached statistical significance in presence under the first-person condition (p < 0.010, ηp2 = 0.084). In spite of these differences, the participants experienced a vivid sense of embodiment and presence in almost all conditions. These results provide first evidence that, although less intensively, embodiment and presence are similarly experienced by individuals who have suffered a stroke and by healthy individuals, which could support the vividness of their experience and, consequently, the effectiveness of VR-based interventions.

The ability of virtual reality (VR) to recreate controlled, immersive, and interactive environments that provide intensive and customized exercises has motivated its therapeutic use after stroke. Interaction and bodily presence in VR-based interventions is usually mediated through virtual selves, which synchronously represent body movements or responses to events on external input devices. Embodied self-representations in the virtual world not only provide an anchor for visuomotor tasks, but their morphologies can have behavioral implications. While research has focused on the underlying subjective mechanisms of exposure to VR on healthy individuals, the transference of these findings to individuals with stroke is not evident and remains unexplored, which could affect the experience and, ultimately, the clinical effectiveness of neurorehabilitation interventions. This study determined and compared the sense of embodiment and presence elicited by a virtual environment under different perspectives and levels of immersion in healthy subjects and individuals with stroke. Forty-six healthy subjects and 32 individuals with stroke embodied a gender-matched neutral avatar in a virtual environment that was displayed in a first-person perspective with a head-mounted display and in a third-person perspective with a screen, and the participants were asked to interact in a virtual task for 10 min under each condition in counterbalanced order, and to complete two questionnaires about the sense of embodiment and presence experienced during the interaction. The sense of body-ownership, self-location, and presence were more vividly experienced in a first-person than in a third-person perspective by both healthy subjects (p < 0.001, η p 2 = 0.212; p = 0.005, η p 2 = 0.101; p = 0.001, η p 2 = 0.401, respectively) and individuals with stroke (p = 0.019, η p 2 = 0.070; p = 0.001, η p 2 = 0.135; p = 0.014, η p 2 = 0.077, respectively). In contrast, no agency perspective-related differences were found in any group. All measures were consistently higher for healthy controls than for individuals with stroke, but differences between groups only reached statistical significance in presence under the first-person condition (p < 0.010, η p 2 = 0.084). In spite of these differences, the participants experienced a vivid sense of embodiment and presence in almost all conditions. These results provide first evidence that, although less intensively, embodiment and presence are similarly experienced by individuals who have suffered a stroke and by healthy individuals, which could support the vividness of their experience and, consequently, the effectiveness of VR-based interventions. [ABSTRACT FROM AUTHOR]

Highlights • Insula and opercula perform various and complicated functions. • Insula have functions in cardiovascular systems. • Posterior insula and parietal operculum related to body-ownership symptoms. • Complicated visual phenomena related to temporal operculum. Abstract Purpose Using direct intracerebral electrical stimulation (ES) in epileptic patients to evoke symptoms to help identify the functional neuroanatomy of the insular lobe and opercula. Methods We selected 43 patients who had at least 1 electrode inserted into the insula or opercula via an oblique approach among 135 patients with intractable epilepsy. Bipolar stimulation was chosen, and the stimulation parameters of the biphasic waves included a pulse width of 0.2 ms, a frequency of 50 Hz, a duration of 3 s, and an intensity gradually increasing from 0.5 to 4 mA. Results In total, 93 electrodes were implanted into the insula or insular opercula, and 169 of 281 contacts (60.1%) evoked 212 responses by ES of the insula. 142 responses were induced by stimulating the insular opercula in 126 of 343 sites (36.7%). Usual responses, such as somatosensory, visceral sensory, speech, auditory, and motor responses, were evoked. In addition, rarely reported responses, including cardiovascular symptoms (tachycardia), visual symptoms evoked by ES of the parietal and temporal opercula, and vestibular symptoms (like the loss of ownership of the body) evoked following stimulation of the posterior insula and parietal operculum, were also induced in our study. Conclusions The insula and opercula perform various and complicated functions. The posterior insula and parietal operculum could play important roles in body-ownership symptoms. The complicated visual phenomena were partially related to the temporal operculum. [ABSTRACT FROM AUTHOR]

The Rubber Hand Illusion (RHI) is a perceptual illusion that enables integration of artificial limbs into the body representation through combined multisensory integration. Most previous studies investigating the RHI have involved young healthy adults within a very narrow age range (typically 20–30 years old). The purpose of this paper was to determine the influence of age on the RHI. The RHI was performed on 93 healthy adults classified into three groups of age (20–35 years old, N = 41; 36–60 years old, N = 28; and 61–80 years old, N = 24), and its effects were measured with subjective (Embodiment of Rubber Hand Questionnaire), behavioral (proprioceptive drift), and physiological (changes in skin temperature and conductance) measures. There were neither significant differences among groups in any response, nor significant covariability or correlation between age and other measures (but for skin temperature), which suggests that the RHI elicits similar responses across different age groups in the adult phase. [ABSTRACT FROM AUTHOR]

The feeling of body-ownership can be experimentally manipulated using the rubber hand illusion (RHI) paradigm. Participants experience a sense of ownership over an artificial hand when their hidden real hand and the visible artificial hand are synchronously stroked. Using lesion masks and behavioral data from a previous study on RHI failure in acute stroke patients, we here employed lesion network-symptom-mapping (LNSM) based on normative functional connectome data to identify lesion-dependent network connectivity related to the experience of self-attribution of an artificial hand in the RHI paradigm. We found that failure to experience the RHI was associated with higher normative lesion-dependent network connectivity to the right temporoparietal junction (rTPJ), right anterior Insula (raI) and right inferior frontal gyrus (rIFG). Since these areas were spared by the infarction in most patients with RHI failure (89% for rTPJ and 94% for raI/rIFG), the analysis suggests that remote dysfunction in rTPJ, raI, and rIFG accounted for RHI failure. These results highlight the potential role of rTPJ, raI, and rIFG in bodily self-consciousness. LNSM is a powerful tool capable of delineating the architecture of functional networks underlying complex cognitive function. [ABSTRACT FROM AUTHOR]

Imitative stimuli presented from a first-person perspective (FPP) produce stronger visuomotor effects than those presented from a third-person perspective (TPP) due to the relatively greater response of the mirror neuron system (MNS) to FPP stimuli. Some previous studies utilizing TPP stimuli have reported no differences in MNS activity between moving and static bodies' stimuli. However, few studies have compared visuomotor effects of such stimuli when presented in the FPP. To clarify this issue, we measured cortical activation in 17 participants during a functional magnetic resonance imaging (MRI) imitation task involving three conditions: moving (a lifting finger was presented), static (an 'X' appeared on a static finger), and control (an 'X' appeared on a button). All stimuli were presented from the FPP or TPP. Participants were asked to lift the finger corresponding to the imitative stimulus. In the FPP condition, moving stimuli elicited greater MNS activation than static stimuli. Furthermore, such movement effects were stronger in the MNS and insula (a region associated with body-ownership) for FPP stimuli than for TPP stimuli. Psychophysiological interaction analysis revealed increased connectivity between the MNS and insula for moving stimuli in the FPP condition. These findings suggest that bodily movements presented in the FPP elicit a greater visuomotor response than static body presented in the FPP, and that the visuomotor effects of bodily movements were greater in the FPP condition than in the TPP condition. Our analyses further indicated that such responses are processed via the neural system underlying body-ownership. Hum Brain Mapp 38:6218-6229, 2017. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Research on bodily awareness has focused on body illusions with an aim to explore the possible dissociation of our bodily awareness from our own body. It has provided insights into how our sensory modalities shape our sense of embodiment, and it has raised important questions regarding the malleability of our sense of ownership over our own body. The issue, however, is that this research fails to consider an important distinction in how we experience our body. There are indeedtwoways in which we can be aware of our body: via observational awareness, which involves attending to the body as an object, and via non-observational awareness, where the body is given as the subject of experience and does not involve attention. The research to date has focused on the former—observational bodily awareness—and has left the latter—non-observational bodily awareness—in the dark. This is detrimental to ever formulating a complete account of how we are aware of our body. It is understandable, however, because of the inherent problem in studying non-observational bodily awareness: how would you instruct subjects to report on their unattended bodily awareness? In view to resolving this problem, I propose here a working hypothesis on the basis of research on interoception and the rubber hand illusion, and on the effect of meditation on awareness and attention. This working hypothesis can show us a way to begin studying non-observational bodily awareness, and finally build a complete theory of bodily awareness. [ABSTRACT FROM AUTHOR]

Interoceptive and exteroceptive information are both essential for the construction and update of self-awareness. Whereas several studies have shown how interoceptive accuracy or cardiac feedback influences body-awareness, no studies have looked at the reverse effect, namely how exteroceptively-driven changes in body-ownership and self-identification can influence individuals' ability to detect internal bodily signals. We exposed participants to the Rubber Hand Illusion (Experiment 1) and to the Enfacement Illusion (Experiment 2), and tested how this change in the sense of body-ownership and self-identification affected their interoceptive accuracy (IAcc). The heartbeat-counting task was used to measure IAcc before the bodily illusions, and then the same task was interleaved with periods of visuo-tactile stimulation, during which synchronous and asynchronous multisensory stimulation was applied. We found that a change in body-ownership significantly improved performance of participants with lower interoceptive accuracy. In contrast, a change in self-identification significantly decreased performance of participants with higher interoceptive accuracy. These results suggest that changes in different domains of self-awareness can differentially impact individuals' ability to accurately detect signals arising from within the body, highlighting the distinct role that interoceptive signals play for different facets of bodily self-consciousness. [ABSTRACT FROM AUTHOR]

Stroke can lead to motor impairments that can affect the body structure and restraint mobility. We hypothesize that brain lesions and their motor sequelae can distort the body schema, a sensorimotor map of body parts and elements in the peripersonal space through which human beings embody the reachable space and ready the body for forthcoming movements. Two main constructs have been identified in the embodiment mechanism: body-ownership, the sense that the body that one inhabits is his/her own, and agency, the sense that one can move and control his/her body. To test this, the present study simultaneously investigated different embodiment subcomponents (body-ownership, localization, and agency) and different neurophysiological measures (galvanic skin response, skin temperature, and surface electromyographic activity), and the interaction between them, in clinically-controlled hemiparetic individuals with stroke and in healthy subjects after the rubber hand illusion. Individuals with stroke reported significantly stronger body-ownership and agency and reduced increase of galvanic skin response, skin temperature, and muscular activity in the stimulated hand. We suggest that differences in embodiment could have been motivated by increased plasticity of the body schema and pathological predominance of the visual input over proprioception. We also suggest that differences in neurophysiological responses could have been promoted by a suppression of the reflex activity of the sympathetic nervous system and by the involvement of the premotor cortex in the reconfiguration of the body schema. These results could evidence a body schema plasticity promoted by the brain lesion and a main role of the premotor cortex in this mechanism. [ABSTRACT FROM AUTHOR]

Awareness of our own bodies (sense of body-ownership) and actions (sense of agency) is fundamental for self-consciousness. In the rubber hand illusion, watching a rubber hand being stroked synchronously as one's own unseen hand is also stroked causes the observer to attribute the rubber hand to their own body. The findings of the series of experiments reported here suggest that body-ownership, measured using proprioceptive drift, is elicited by the external acting proxy that drives the sense of agency. While participants clasped and unclasped their left hand for 60 s, they focused on video feedback on a monitor in front of them. Proprioceptive drift was observed only under the conditions, including synchronized conditions, where the sense of agency for the acting proxy occurred, suggesting an essential interaction between body-ownership and agency. [ABSTRACT FROM AUTHOR]

Humans regularly feel a sense of agency (SoA) over events where the causal link between action and outcome is extremely indirect. We have investigated how intermediate (here, a robotic hand) events that intervene between action and outcome may alter SoA, using intentional binding measures. The robotic hand either performed the same movement as the participant (active congruent), or performed a similar movement with another finger (active incongruent). Binding was significantly reduced in the active incongruent relative to the active congruent condition, suggesting that altered embodiment influences SoA. However, binding effects were comparable between a condition where the robot hand made a congruent movement, and conditions where no robot hand was involved, suggesting that intermediate and embodied events do not reduce SoA. We suggest that human sense of agency involves both statistical associations between intentions and arbitrary outcomes, and an effector-specific matching of sensorimotor means used to achieve the outcome. [ABSTRACT FROM AUTHOR]

A central feature of our consciousness is the experience of the self as a unified entity residing in a physical body, termed bodily self-consciousness. This phenomenon includes aspects such as the sense of owning a body (also known as body ownership) and has been suggested to arise from the integration of sensory and motor signals from the body. Several studies have shown that temporally synchronous tactile stimulation of the real body and visual stimulation of a fake or virtual body can induce changes in bodily self-consciousness, typically resulting in a sense of illusory ownership over the fake body. The present study assessed the effect of anatomical congruency of visuo-tactile stimulation on bodily self-consciousness. A virtual body was presented and temporally synchronous visuo-tactile stroking was applied simultaneously the participants’ body and to the virtual body. We manipulated the anatomical locations of the visuo-tactile stroking (i.e. on the back, on the leg), resulting in congruent stroking (stroking was felt and seen on the back or the leg) or incongruent stroking (i.e. stroking was felt on the leg and seen on the back). We measured self-identification with the virtual body and self-location as well as skin temperature. Illusory self-identification with the avatar as well as changes in self-localization were experienced in the congruent stroking conditions. Participants showed a decrease in skin temperature across several body locations during congruent stimulation. These data establish that the full-body illusion alters bodily self-consciousness and instigates widespread physiological changes in the participant’s body.

The neural correlates of "self" identified by neuroimaging studies differ depending on which aspects of self are addressed. Here, three categories of self are proposed based on neuroimaging findings and an evaluation of the likely underlying cognitive processes. The physical self, representing self-agency of action, body-ownership, and bodily self-recognition, is supported by the sensory and motor association cortices located primarily in the right hemisphere. The interpersonal self, representing the attention or intentions of others directed at the self, is supported by several amodal association cortices in the dorsomedial frontal and lateral posterior cortices. The social self, representing the self as a collection of context-dependent social-values, is supported by the ventral aspect of the medial prefrontal cortex and the posterior cingulate cortex. Despite differences in the underlying cognitive processes and neural substrates, all three categories of self are likely to share the computational characteristics of the forward model, which is underpinned by internal schema or learned associations between one's behavioral output and the consequential input. Additionally, these three categories exist within a hierarchical layer structure based on developmental processes that updates the schema through the attribution of prediction error. In this account, most of the association cortices critically contribute to some aspect of the self through associative learning while the primary regions involved shift from the lateral to the medial cortices in a sequence from the physical to the interpersonal to the social self. [ABSTRACT FROM AUTHOR]

A central feature of our consciousness is the experience of the self as a unified entity residing in a physical body, termed bodily self-consciousness. This phenomenon includes aspects such as the sense of owning a body (also known as body ownership) and has been suggested to arise from the integration of sensory signals from the body. Several studies have shown that temporally synchronous tactile stimulation of the real body and visual stimulation of a fake or virtual body can induce changes in bodily self-consciousness, typically resulting in a sense of illusory ownership over the fake body. The present study assessed the effect of anatomical congruency of visuo-tactile stimulation on bodily self-consciousness. A virtual body was presented and temporally synchronous visuo-tactile stroking was applied simultaneously to the participants' body and to the virtual body. We manipulated the anatomical locations of the visuo-tactile stroking (i.e., on the back, on the leg), resulting in congruent stroking (stroking was felt and seen on the back or the leg) or incongruent stroking (i.e., stroking was felt on the leg and seen on the back). We measured self-identification with the virtual body and self-location as well as skin temperature. Illusory self-identification with the avatar as well as changes in self-location were experienced in the congruent stroking conditions. Participants showed a decrease in skin temperature across several body locations during congruent stimulation. These data establish that the full-body illusion (FBI) alters bodily self-consciousness and instigates widespread physiological changes in the participant's body. [ABSTRACT FROM AUTHOR]

Abstract: Multisensory stimulation has been shown to alter the sense of body-ownership. Given that perceived similarity between one’s own body and those of others is crucial for social cognition, we investigated whether multisensory stimulation can lead participants to experience ownership over a hand of different skin colour. Results from two studies using introspective, behavioural and physiological methods show that, following synchronous visuotactile (VT) stimulation, participants can experience body-ownership over hands that seem to belong to a different racial group. Interestingly, a baseline measure of implicit racial bias did not predict whether participants would experience the RHI, but the overall strength of experienced body-ownership seemed to predict the participants’ post-illusion implicit racial bias with those who experienced a stronger RHI showing a lower bias. These findings suggest that multisensory experiences can override strict ingroup/outgroup distinctions based on skin colour and point to a key role for sensory processing in social cognition. [Copyright &y& Elsevier]

Abstract: The exact relation between the sense that one''s body is one''s own (body-ownership) and the sense that one controls one''s own bodily actions (agency) has been the focus of much speculation, but remains unclear. On an ‘additive’ model, agency and body-ownership are strongly related; the ability to control actions is a powerful cue to body-ownership. This view implies a component common to the senses of body-ownership and agency, plus possible additional components unique to agency. An alternative ‘independence’ model holds that agency and body-ownership are qualitatively different experiences, triggered by different inputs, and recruiting distinct brain networks. We tested these two specific models by investigating the sensory and motor aspects of body-representation in the brain using fMRI. Activations in midline cortical structures were associated with a sensory-driven sense of body-ownership, and were absent in agency conditions. Activity in the pre-SMA was linked to the sense of agency, but distinct from the sense of body-ownership. No shared activations that would support the additive model were found. The results support the independence model. Body-ownership involves a psychophysiological baseline, linked to activation of the brain''s default mode network. Agency is linked to premotor and parietal areas involved in generating motor intentions and subsequent action monitoring. [Copyright &y& Elsevier]

Abstract: Empirical research on the bodily self has only recently started to investigate how the link between a body and the experience of this body as mine is developed, maintained or disturbed. The Rubber Hand Illusion has been used as a model instance of the normal sense of embodiment to investigate the processes that underpin the experience of body-ownership. This review puts forward a neurocognitive model according to which body-ownership arises as an interaction between current multisensory input and internal models of the body. First, a pre-existing stored model of the body distinguishes between objects that may or may not be part of one''s body. Second, on-line anatomical and postural representations of the body modulate the integration of multisensory information that leads to the recalibration of visual and tactile coordinate systems. Third, the resulting referral of tactile sensation will give rise to the subjective experience of body-ownership. These processes involve a neural network comprised of the right temporoparietal junction which tests the incorporeability of the external object, the secondary somatosensory cortex which maintains an on-line representation of the body, the posterior parietal and ventral premotor cortices which code for the recalibration of the hand-centred coordinate systems, and the right posterior insula which underpins the subjective experience of body-ownership. The experience of body-ownership may represent a critical component of self-specificity as evidenced by the different ways in which multisensory integration in interaction with internal models of the body can actually manipulate important physical and psychological aspects of the self. [Copyright &y& Elsevier]

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]

Abstract: The recent distinction between sense of agency and sense of body-ownership has attracted considerable empirical and theoretical interest. The respective contributions of central motor signals and peripheral afferent signals to these two varieties of body experience remain unknown. In the present review, we consider the methodological problems encountered in the empirical study of agency and body-ownership, and we then present a series of experiments that study the interplay between motor and sensory information. In particular, we focus on how multisensory signals interact with body representations to generate the sense of body-ownership, and how the sense of agency modulates the sense of body-ownership. Finally, we consider the respective roles of efferent and afferent signals for the experience of one’s own body and actions, in relation to self-recognition and the recognition of other people’s actions. We suggest that the coherent experience of the body depends on the integration of efferent information with afferent information in action contexts. Overall, whereas afferent signals provide the distinctive content of one’s own body experience, efferent signals seem to structure the experience of one’s own body in an integrative and coherent way. [Copyright &y& Elsevier]

Abstract: We investigated how motor agency in the voluntary control of body movement influences body awareness. In the Rubber Hand Illusion (RHI), synchronous tactile stimulation of a rubber hand and the participant’s hand leads to a feeling of the rubber hand being incorporated in the participant’s own body. One quantifiable behavioural correlate of the illusion is an induced shift in the perceived location of the participant’s hand towards the rubber hand. Previous studies showed that the induced changes in body awareness are local and fragmented: the proprioceptive drift is largely restricted to the stimulated finger. In the present study, we investigated whether active and passive movements, rather than tactile stimulation, would lead to similarly fragmented body awareness. Participants watched a projected image of their hand under three conditions: active finger movement, passive finger movement, and tactile stimulation. Visual feedback was either synchronous or asynchronous with respect to stimulation of the hand. A significant overall RHI, defined as greater drifts following synchronous than asynchronous stimulation, was found in all cases. However, the distribution of the RHI across stimulated and non-stimulated fingers depended on the kind of stimulation. Localised proprioceptive drifts, specific to the stimulated finger, were found for tactile and passive stimulation. Conversely, during active movement of a single digit, the proprioceptive drifts were not localised to that digit, but were spread across the whole hand. Whereas a purely proprioceptive sense of body-ownership is local and fragmented, the motor sense of agency integrates distinct body-parts into a coherent, unified awareness of the body. [Copyright &y& Elsevier]

Self-consciousness consists of several dissociable experiences, including the sense of ownership of one's body and the sense of agency over one's action consequences. The relationship between body-ownership and the sense of agency has been described by different neurocognitive models, each providing specific neurofunctional predictions. According to an "additive" model, the sense of agency entails body-ownership, while an alternative "independence" hypothesis suggests that they represent two qualitatively different processes, underpinned by distinct brain systems. We propose a third "interactive" model, arguing the interdependence between body-ownership and the sense of agency: these constructs might represent different experiences with specific and exclusive brain correlates, but they also could partly overlap at the neurofunctional level. Here we test these three neurocognitive models by reviewing the available neurofunctional literature of body-ownership and the sense of agency, with a quantitative meta-analytical approach that allowed us to compare their neural correlates statistically. We identified (i) a body-ownership-specific network including the left inferior parietal lobule and the left extra-striate body area, (ii) a sense-of-agency-specific network including the left SMA, the left posterior insula, the right postcentral gyrus, and the right superior temporal lobe and (iii) a shared network in the left middle insula. These results provide support for the interactive neurocognitive model of body-ownership and the sense of agency. Body-ownership involves a sensory network in which multisensory inputs are integrated to be self-attributed. On the other hand, the sense of agency is specifically associated with premotor and sensory-motor areas, typically involved in generating motor predictions and in action monitoring. Finally, body-ownership and the sense of agency interact at the level of the left middle insula, a high-level multisensory hub engaged in body and action awareness in general., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

We have previously shown that people are more sensitive at detecting asynchrony between a self-generated movement and delayed visual feedback when the perspective of the movement matches the 'natural view' suggesting an internal, visual, canonical body representation (Hoover and Harris, 2011). Is there a similar variation in sensitivity for parts of the body that cannot be seen in a first-person perspective? To test this, participants made movements with their hands and head (viewing their face or the back of their head) under four viewing conditions: (1) the natural (or direct) view, (2) mirror-reversed, (3) inverted, and (4) inverted and mirror-reversed. Participants indicated which of two periods (one with a minimum delay, the other with an added delay of 33–264 ms) was delayed and their sensitivity to delay was calculated. A significant linear trend was found when comparing sensitivity to detect cross-modal asynchrony in the 'natural' or 'direct' view condition across body parts; where sensitivity was greatest when viewing body parts seen most often (hands), intermediary for viewing body parts that are seen only indirectly (moving head while viewing face), and least for viewing body parts that are never seen at all (moving head while viewing back of the head). Further, dependency on viewpoint was most evident for body parts that are seen most often or indirectly, but not for body parts that are never seen. Results are discussed in terms of a visual representation of the body. [ABSTRACT FROM AUTHOR]

The neural correlates of "self" identified by neuroimaging studies differ depending on which aspects of self are addressed. Here, three categories of self are proposed based on neuroimaging findings and an evaluation of the likely underlying cognitive processes. The physical self, representing self-agency of action, body-ownership, and bodily self-recognition, is supported by the sensory and motor association cortices located primarily in the right hemisphere. The interpersonal self, representing the attention or intentions of others directed at the self, is supported by several amodal association cortices in the dorsomedial frontal and lateral posterior cortices. The social self, representing the self as a collection of context-dependent social-values, is supported by the ventral aspect of the medial prefrontal cortex and the posterior cingulate cortex. Despite differences in the underlying cognitive processes and neural substrates, all three categories of self are likely to share the computational characteristics of the forward model, which is underpinned by internal schema or learned associations between one's behavioral output and the consequential input. Additionally, these three categories exist within a hierarchical layer structure based on developmental processes that updates the schema through the attribution of prediction error. In this account, most of the association cortices critically contribute to some aspect of the self through associative learning while the primary regions involved shift from the lateral to the medial cortices in a sequence from the physical to the interpersonal to the social self.