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This article explores the relationship between sensory perception, multisensory integration, and bodily self-representation. It includes seven novel publications that offer insights into how our brains construct and integrate sensory experiences, reshaping our understanding of perception and consciousness. The studies cover various topics, such as the impact of brain damage on somatosensory processing, rehabilitation techniques, dysregulated eating behaviors, self-face representation in children, naturalistic limb movements, and the neural differences between airplane pilots and non-pilots. The document also discusses a study that used virtual reality tasks to examine the impact of congruent and incongruent sensory-motor interactions on spatial perception, finding that participants exhibited a bias in left-right tactile localization and a shift in the perceived body midline. These findings contribute to our understanding of spatial biases in virtual environments and have implications for bodily perception. [Extracted from the article]

The ability to identify our own body and its boundaries is crucial for survival. Ideally, the sooner we learn to discriminate external stimuli occurring close to our body from those occurring far from it, the better (and safer) we may interact with the sensory environment. However, when this mechanism emerges within ontogeny is unknown. Is it something acquired throughout infancy, or is it already present soon after birth? The presence of a spatial modulation of multisensory integration (MSI) is considered a hallmark of a functioning representation of the body position in space. Here, we investigated whether MSI is present and spatially organized in 18- to 92-h-old newborns. We compared electrophysiological responses to tactile stimulation when concurrent auditory events were delivered close to, as opposed to far from, the body in healthy newborns and in a control group of adult participants. In accordance with previous studies, adult controls showed a clear spatial modulation of MSI, with greater superadditive responses for multisensory stimuli close to the body. In newborns, we demonstrated the presence of a genuine electrophysiological pattern of MSI, with older newborns showing a larger MSI effect. Importantly, as for adults, multisensory superadditive responses were modulated by the proximity to the body. This finding may represent the electrophysiological mechanism responsible for a primitive coding of bodily self boundaries, thus suggesting that even just a few hours after birth, human newborns identify their own body as a distinct entity from the environment. [ABSTRACT FROM AUTHOR]

Abstract: Binding across sensory modalities yields substantial perceptual benefits, including enhanced speech intelligibility. The coincidence of sensory inputs across time is a fundamental cue for this integration process. Recent work has suggested that individuals with diagnoses of schizophrenia (SZ) and autism spectrum disorder (ASD) will characterize auditory and visual events as synchronous over larger temporal disparities than their neurotypical counterparts. Namely, these clinical populations possess an enlarged temporal binding window (TBW). Although patients with SZ and ASD share aspects of their symptomatology, phenotypic similarities may result from distinct etiologies. To examine similarities and variances in audiovisual temporal function in these two populations, individuals diagnosed with ASD (n = 46; controls n = 40) and SZ (n = 16, controls = 16) completed an audiovisual simultaneity judgment task. In addition to standard psychometric analyses, synchrony judgments were assessed using Bayesian causal inference modeling. This approach permits distinguishing between distinct causes of an enlarged TBW: an a priori bias to bind sensory information and poor fidelity in the sensory representation. Findings indicate that both ASD and SZ populations show deficits in multisensory temporal acuity. Importantly, results suggest that while the wider TBWs in ASD most prominently results from atypical priors, the wider TBWs in SZ results from a trend toward changes in prior and weaknesses in the sensory representations. Results are discussed in light of current ASD and SZ theories and highlight that different perceptual training paradigms focused on improving multisensory integration may be most effective in these two clinical populations and emphasize that similar phenotypes may emanate from distinct mechanistic causes. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted the role of multisensory integration as a key mechanism of self-consciousness. In particular, integration of bodily signals within the peripersonal space (PPS) underlies the experience of the self in a body we own (self-identification) and that is experienced as occupying a specific location in space (self-location), two main components of bodily self-consciousness (BSC). Experiments investigating the effects of multisensory integration on BSC have typically employed supra-threshold sensory stimuli, neglecting the role of unconscious sensory signals in BSC, as tested in other consciousness research. Here, we used psychophysical techniques to test whether multisensory integration of bodily stimuli underlying BSC also occurs for multisensory inputs presented below the threshold of conscious perception. Our results indicate that visual stimuli rendered invisible through continuous flash suppression boost processing of tactile stimuli on the body (Exp. 1), and enhance the perception of near-threshold tactile stimuli (Exp. 2), only once they entered PPS. We then employed unconscious multisensory stimulation to manipulate BSC. Participants were presented with tactile stimulation on their body and with visual stimuli on a virtual body, seen at a distance, which were either visible or rendered invisible. We found that participants reported higher self-identification with the virtual body in the synchronous visuo-tactile stimulation (as compared to asynchronous stimulation; Exp. 3), and shifted their self-location toward the virtual body (Exp.4), even if stimuli were fully invisible. Our results indicate that multisensory inputs, even outside of awareness, are integrated and affect the phenomenological content of self-consciousness, grounding BSC firmly in the field of psychophysical consciousness studies. [ABSTRACT FROM AUTHOR]

Bodily self-consciousness (BSC) refers to experience of one’s self as located within an owned body (self-identification) and as occupying a specific location in space (self-location). BSC can be altered through multisensory stimulation, as in the Full Body Illusion (FBI). If participants view a virtual body from a distance being stroked, while receiving synchronous tactile stroking on their physical body, they feel as if the virtual body were their own and they experience, subjectively, to drift toward the virtual body. Here we hypothesized that – while normally the experience of the body in space depends on the integration of multisensory body-related signals within a limited space surrounding the body (i.e. peripersonal space, PPS) – during the FBI the boundaries of PPS would shift toward the virtual body, that is, toward the position of experienced self-location. To test this hypothesis, we used synchronous visuo-tactile stroking to induce the FBI, as contrasted with a control condition of asynchronous stroking. Concurrently, we applied an audio–tactile interaction paradigm to estimate the boundaries of PPS. PPS was measured in front of and behind the participants’ body as the distance where tactile information interacted with auditory stimuli looming in space toward the participant’s physical body. We found that during synchronous stroking, i.e. when participants experienced the FBI, PPS boundaries extended in the front-space, toward the avatar, and concurrently shrunk in the back-space, as compared to the asynchronous stroking control condition, when FBI was induced. These findings support the view that during the FBI, PPS boundaries translate toward the virtual body, such that the PPS representation shifts from being centered at the location of the physical body to being now centered at the subjectively experienced location of the self. [ABSTRACT FROM AUTHOR]

Recent neurobiological accounts of schizophrenia have included an emphasis on changes in sensory processing. These sensory and perceptual deficits can have a cascading effect onto higher-level cognitive processes and clinical symptoms. One form of sensory dysfunction that has been consistently observed in schizophrenia is altered temporal processing. In this study, we investigated temporal processing within and across the auditory and visual modalities in individuals with schizophrenia (SCZ) and age-matched healthy controls. Individuals with SCZ showed auditory and visual temporal processing abnormalities, as well as multisensory temporal processing dysfunction that extended beyond that attributable to unisensory processing dysfunction. Most importantly, these multisensory temporal deficits were associated with the severity of hallucinations. This link between atypical multisensory temporal perception and clinical symptomatology suggests that clinical symptoms of schizophrenia may be at least partly a result of cascading effects from (multi)sensory disturbances. These results are discussed in terms of underlying neural bases and the possible implications for remediation. [ABSTRACT FROM AUTHOR]