Conference Agenda

In recent decades, virtual reality (VR) technology has been rapidly developed and allows us to immerse ourselves in virtual environment with our vicarious body (i.e., avatar). The avatar usually has no tactile sensation, which suggests also no pain sensation although any hurting objects contact with the avatar's body. If vicarious pain perception could be induced by seeing the avatar hurt, the intensity of pain and the neural response to the nociceptive stimulation could be modulated by the embodiment of the avatar's body. In the present study, the neural responses were measured by EEG when experimental participants saw that the needle of an injector pricked on the fingers of the avatar's hand with or without simultaneous vibration on the finger. Under four conditions (i.e., spatially congruent visuotactile stimulation, incongruent, visual only, and vibration only), the participants evaluated the embodiment and vicarious pain using questionnaires. The significant correlation between the embodiment and vicarious pain was observed, while N1, as an ERP component to the nociceptive stimulation, was not modulated by these subjective ratings. These results suggest that visually presented nociceptive stimulation without any painful sensations could not evoke a neural response related to nociceptive information processing, whereas some participants felt vicarious pain, strengthened by embodiment of the avatar body.

Recent technological advances increasingly blur the boundaries between real and virtual selves, with profound implications in our progressively hyper-digitalized world. Here, we investigated the neural and behavioral signatures underlying joint improvisation and self-other boundaries in dynamic interactions across real and virtual environments. In Study 1, we present data from 10 dyads performing a 1D finger-movement mirror game while magnetoencephalography (MEG) was simultaneously recorded from both subjects alongside finger kinematics tracked via accelerometers. We compared source-level power and intra-brain connectivity across experimental conditions. Alpha-band power in widespread brain regions was reduced in social (interaction or observed action) compared to individual (isolated) action, with this reduction restricted to occipital areas for interaction vs. observed action. Beta suppression was observed in interaction compared to individual action (observed or in isolation), with left TPJ suppression in observed vs. isolated action. Alpha-band intra-brain connectivity decreased in interaction compared to individual action, involving occipital, temporal, parietal, and frontal regions. This reduction may reflect diminished self-monitoring in joint performance, facilitating interpersonal coupling. In Study 2, we further investigate joint improvisation dynamics in real-life and virtual reality (VR) settings, emphasizing moments of togetherness, where self-other boundaries blur. Pairs of participants engage in mirror game interactions both in person and embodying VR avatars, with electroencephalography (EEG), electrocardiography (ECG), and motion capture simultaneously recorded in a hyperscanning setup. Our findings contribute to the understanding of brain oscillations in interpersonal motor interactions and address the smoky boundaries between self and other in real and virtual worlds.

Prior expectations shape how we see the world and monitor our feelings. In particular, it has long been evident that priors and ambiguous sensory input interact to determine the course of perceptual decision-making. However, although numerous theories emphasize an important role for interoceptive inference in shaping our exteroceptive perception, there is as yet no evidence as to how visceral rhythms modulate the interaction between priors and input.

Using a novel perceptual learning task, we analysed how cyclic fluctuations of visceral signals in the cardiac domain influence affective perceptual inferences. 274 participants completed the task, in which they had to learn the probabilistic associations between arbitrary visual cues and happy or angry faces of varying valence intensities while physiological signals (i.e. electrocardiogram) were recorded. This design enabled us to manipulate the sensory uncertainty of stimuli and the expected precision of prior expectations. Having tested whether sensory uncertainty, prior expectation and valence influence perceptual behaviour including reaction time, accuracy and also confidence, we then examined how the interaction between these predictors related to the cardiac cycle.

We found that cardiac dynamics over the entire trial encode sensory uncertainty and valence. Furthermore, we identified effects of these behavioural indices on confidence, reaction time and accuracy.

Overall, these results show that there is both top-down modulation, with visceral signals adapting to the perceived characteristics of the sensory environment, and bottom-up modulation, with the phase of visceral cycles influencing perceptual and metacognitive biases. Perceptual consciousness in the affective domain is modulated by this delicate balance.

Introduction

The bodily self is a minimal form of self relying on bodily experiences such as self-location, body ownership, agency, and first-person perspective. These experiences depend on multisensory integration in a network encompassing the temporo-parietal junction, insula, postcentral gyrus, and premotor cortex. While this network has been studied using fMRI, intracranial electrical brain stimulation (EBS) provides a unique opportunity for functional mapping. This study presents primary research through a large whole-brain functional mapping of the bodily self in epilepsy patients.

Methods

We retrospectively analyzed EBS-induced clinical manifestations in 329 epilepsy patients who underwent stereo-electroencephalography. Depth electrodes were implanted in 254 left and 260 right hemispheres. A total of 11,004 stimulations elicited 2,320 clinical responses. We examined alterations in self-location, body ownership, agency, first-person perspective, and body image, identifying the electrode contacts responsible. Functional connectivity changes associated with bodily self disturbances were also assessed.

Results

Bodily self disturbances (n=78, 3.4% of all evoked responses) were observed in 50 patients, primarily affecting body image, self-location, and agency. Key regions included the anterior and posterior cingulate cortex, insula, hippocampus, SMA, parietal operculum, and precuneus, with right hemisphere dominance. Functional connectivity analysis revealed decreased connectivity of the inferior parietal lobule (IPL) and a specific IPL-middle temporal gyrus disconnection.

Conclusion

This study provides causal evidence for a multisensory network underlying the bodily self and suggests that IPL disconnection, a key region from the default mode network, plays a central role in bodily self disturbances. These findings refine theoretical models and have neurosurgical and neuropsychiatric implications.

Experienced meditation practitioners often report altered states of self-consciousness, including non-dual awareness and non-self states. However, few studies provide empirical evidence for these effects, particularly from the neuroscientific theory of the minimal self, or bodily self-consciousness (BSC). To address this, we developed a novel meditation practice integrating traditional meditation with Virtual Reality (VR) techniques that can modulate BSC thanks to bodily awareness manipulation and shifts in the first-person perspective. In two studies, participants without meditation experience practiced meditation in VR in two conditions. In one condition, BSC was altered with focused bodily awareness combined with shifts to a third-person perspective (3PP). In the other condition, the first-person perspective was maintained (1PP). We recorded 64-channel electroencephalography (EEG) and electrocardiography (ECG), assessed selected questionnaires, and measured self-identification sensitivity with the full-body illusion (FBI). In the 3PP condition, participants reported stronger experiences of disembodiment and reduced salience of perceived body boundaries. The FBI results suggested reduced self-identification in the 3PP condition compared to the 1PP, especially during the asynchronous FBI. EEG data revealed more negative amplitudes of heart-beat evoked potentials (HEP) during the 3PP condition, likely reflecting activation of the posterior cingulate cortex associated with decreased BSC levels, alongside reduced alpha-band oscillations, potentially indicating multisensory integration in the temporal-parietal region. Leveraging a new VR-supported meditation platform and methods, these data link the sense of self in traditional meditation practice to the neuroscience of the bodily self, based on subjective, behavioral, and neural measures.

Affective touch is slowly moving, low-force mechanical tactile stimulation which is often perceived as enjoyable and is considered key for emotional social bonding. Previous work illustrated that observing other people being touched activates the same cortical areas involved in direct tactile experiences, i.e. vicarious touch. Depersonalisation (DP) is characterized by distressing feelings of being detached from one’s body and others, often described as being “out of touch” with oneself. We conducted two online experiments looking at the relationship between non-clinical experiences of DP and vicarious affective touch and self touch. We found that unlike people with higher DP experiences, low DP people rate the perceived pleasantness of the imagined social touch as received by the self higher than if received by the other. In Experiment 2, we designed a new affective self-touch intervention to explore the effect of affective self-touch stroking on one’s dorsal forearm on the perceived pleasantness and vividness of tactile experiences. We found that both low and high DP participants, following the affective self-touch intervention, report significantly higher ratings of vividness but not pleasantness of tactile experiences. These findings may have key implications for potential sensory tactile-based interventions for people experiencing distressing feelings of DP