Search

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., (Copyright © 2018 Elsevier B.V. All rights reserved.)

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., (Copyright © 2016 Elsevier B.V. All rights reserved.)

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., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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]

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: 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]