1,721,453 research outputs found
Coupling Inner and Outer Body for Self-Consciousness
No full textAlthough recent studies on self-consciousness emphasized the importance of bodily processing and multisensory integration, such research has focused solely on bodily signals originating from the outside of the body (i.e., exteroceptive bodily signals) or internal bodily signals from visceral organs (i.e., interoceptive bodily signals) and how each system contributes to self-consciousness, without much interaction between the two approaches. Reviewing the latest evidence on interoceptive bodily processing and the combination of exteroceptive and interoceptive bodily signals for self-consciousness, we propose an integrated neural system reconciling these two largely separated views and delineate how it accounts for fundamental aspects of self-consciousness such as self-identification and self-location, as well as its experienced global unity and temporal continuity.
Heartbeat-evoked cortical responses: Underlying mechanisms, functional roles, and methodological considerations
No full textThe heart continuously and cyclically communicates with the brain. Beyond homeostatic regulation and sensing, recent neuroscience research has started to shed light on brain-heart interactions in diverse cognitive and emotional processes. In particular, neural responses to heartbeats, as measured with the so-called heartbeat-evoked potential, have been shown to be useful for investigating cortical activity processing cardiac signals. In this review, we first overview and discuss the basic properties of the HEP such as underlying physiological pathways, brain regions, and neural mechanisms. We then provide a systematic review of the mental processes associated with cortical HEP activations, notably heartbeat perception, emotional feelings, perceptual awareness, and self-consciousness, in healthy subjects and clinical populations. Finally, we discuss methodological issues regarding the experimental design and data analysis for separating genuine HEP components from physiological artifacts (e.g., cardiac field artifact, pulse artifact) or other neural activities that are not specifically associated with the heartbeat. Findings from this review suggest that when intrinsic limitations (e.g., artifacts) are carefully controlled, the HEP could provide a reliable neural measure for investigating brain-viscera interactions in diverse mental processes.
Behavioral and neurophysiological evidence for altered interoceptive bodily processing in chronic pain
No full textWhereas impaired multisensory processing of bodily stimuli and distorted body representation are well-established in various chronic pain disorders, such research has focused on exteroceptive bodily cues and neglected bodily signals from the inside of the body (or interoceptive signals). Extending existing basic and clinical research, we investigated for the first time interoception and its neurophysiological correlates in patients with complex regional pain syndrome (CRPS). In three different experiments, including a total of 36 patients with CRPS and 42 aged-gender matched healthy controls, we measured interoceptive sensitivity (heart beat counting task, HBC) and neural responses to heartbeats (heartbeat evoked potentials, HEPs). As hypothesized, we observed reduced sensitivity in perceiving interoceptive bodily stimuli, i.e. their heartbeat, in two independent samples of CRPS patients (studies 1 and 2). Moreover, the cortical processing of their heartbeat, i.e. the HEP, was reduced compared to controls (study 3) and reduced interoceptive sensitivity and HEPs were related to CRPS patients’ motor impairment and pain duration. By providing consistent evidence for impaired processing of interoceptive bodily cues in CRPS, this study shows that the perceptual changes occurring in chronic pain include signals originating from the visceral organs, suggesting changes in the neural body representation, that includes next to exteroceptive, also interoceptive bodily signals. By showing that impaired interoceptive processing is associated with clinical symptoms, our findings also encourage the use of interoceptive-related information in future rehabilitation for chronic pain.
How body position influences the perception and conscious experience of corporeal and extrapersonal space
No full textQuand l'esprit met le corps à distance
Full text linkLes illusions de sortie du corps sont des expériences de désincarnation étonnantes, plus fréquentes qu'on ne le croit. Des neurobiologistes commencent à comprendre les mécanismes cérébraux à l'origine de ce phénomène. Ils progressent ainsi dans l'étude de la « conscience de soi »LNC
Hand perceptions induced by single pulse transcranial magnetic stimulation over the primary motor cortex
No full textConceptual processing is referenced to the experienced location of the self, not to the location of the physical body
No full textWe tested whether an experimentally induced change in the experienced location of the self by means of the Full Body Illusion (FBI) would impact high-level cognitive processing. In an implicit association task, participants saw a landscape where words, conveying spatial ("Near", "Far") or social ("Us", "Them") semantic distance appeared either in a proximal or distal position. Words' "semantic" distance was congruent or incongruent to the words' spatial position. Participants were asked to classify words' spatial position. Implicit association judgements were intermingled with sessions of visuo-tactile stimulation, during which participants were touched on their back, while viewing an avatar in the distal position being touched either synchronously or asynchronously. In a control experiment, participants performed the same task while observing a neutral object being touched, as a control. When subjects self-identified with the avatar presented at the distal position, the facilitation effect of the words' spatial-semantic congruency disappeared. The congruency effect did not disappear in case of asynchronous stimulation as well as in the control experiment with the object, where no change in self identification was observed. These results demonstrate that conceptual processing is not referenced to the location of the physical body, but to the experienced location of the self. (C) 2016 Elsevier B.V. All rights reserved.CNPLNC
Transient Modulations of Neural Responses to Heartbeats Covary with Bodily Self-Consciousness
No full textRecent research has investigated self-consciousness associated with the multisensory processing of bodily signals (e.g., somatosensory, visual, vestibular signals), a notion referred to as bodily self-consciousness, and these studies have shown that the manipulation of bodily inputs induces changes in bodily self-consciousness such as self-identification. Another line of research has highlighted the importance of signals from the inside of the body (e.g., visceral signals) and proposed that neural representations of internal bodily signals underlie self-consciousness, which to date has been based on philosophical inquiry, clinical case studies, and behavioral studies. Here, we investigated the relationship of bodily self-consciousness with the neural processing of internal bodily signals. By combining electrical neuroimaging, analysis of peripheral physiological signals, and virtual reality technology in humans, we show that transient modulations of neural responses to heartbeats in the posterior cingulate cortex covary with changes in bodily self-consciousness induced by the full-body illusion. Additional analyses excluded that measured basic cardiorespiratory parameters or interoceptive sensitivity traits could account for this finding. These neurophysiological data link experimentally the cortical mapping of the internal body to self-consciousness.
Neural adaptation accounts for the dynamic resizing of peripersonal space: evidence from a psychophysical-computational approach
Full text linkInteractions between the body and the environment occur within the peripersonal space (PPS), the space immediately surrounding the body. The PPS is encoded by multisensory (audio-tactile, visual-tactile) neurons that possess receptive fields (RFs) anchored on the body and restricted in depth. The extension in depth of PPS neurons' RFs has been documented to change dynamically as a function of the velocity of incoming stimuli, but the underlying neural mechanisms are still unknown. Here, by integrating a psychophysical approach with neural network modeling, we propose a mechanistic explanation behind this inherent dynamic property of PPS. We psychophysically mapped the size of participant's peri-face and peri-trunk space as a function of the velocity of task-irrelevant approaching auditory stimuli. Findings indicated that the peri-trunk space was larger than the peri-face space, and, importantly, as for the neurophysiological delineation of RFs, both of these representations enlarged as the velocity of incoming sound increased. We propose a neural network model to mechanistically interpret these findings: the network includes reciprocal connections between unisensory areas and higher order multisensory neurons, and it implements neural adaptation to persistent stimulation as a mechanism sensitive to stimulus velocity. The network was capable of replicating the behavioral observations of PPS size remapping and relates behavioral proxies of PPS size to neurophysiological measures of multisensory neurons' RF size. We propose that a biologically plausible neural adaptation mechanism embedded within the network encoding for PPS can be responsible for the dynamic alterations in PPS size as a function of the velocity of incoming stimuli. NEW & NOTEWORTHY Interactions between body and environment occur within the peripersonal space (PPS). PPS neurons are highly dynamic, adapting online as a function of body-object interactions. The mechanistic underpinning PPS dynamic properties are unexplained. We demonstrate with a psychophysical approach that PPS enlarges as incoming stimulus velocity increases, efficiently preventing contacts with faster approaching objects. We present a neurocomputational model of multisensory PPS implementing neural adaptation to persistent stimulation to propose a neurophysiological mechanism underlying this effect.LNCOCN
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