Manipulation of the participants' self-localization in a lying position

Healthy human beings are aware of their current position space and are able to distinguish their own body from that of other persons or objects. This capability arises from a coupling of sensory information with cognitive processes, and leads to a representation of the person's self. However, in some clinical cases these processes fail and a person can feel himself to be outside of his physical body, as in the out-of-body experience. These phenomena are interesting to study as they lend insight to certain aspects of bodily self-consciousness, such as self-localization and self-attribution. These aspects can be experimentally manipulated in healthy participants through exposure to conflicting multisensory input, as has been demonstrated with the creation of an ownership's feeling with rubber hand stroked synchronously with the real hand. Here, we worked on the full body by manipulate the self-localization of healthy participants. We used similar protocols as in the study of Lenggenhager et al. (2007) and Ehrsson (2007b) but with a lying position, rather a seated or standing as in the aforementioned studies, which are the commune position when out-of-body experience occurs. Participants were put in a comfortable lying position and saw an image of their body through 3D head mounted display, recorded by a video camera located two meters above them. By providing different temporal and spatial information about a visual-tactile event (stroking on the participants' back or chest) self-localization and identification could be modified in a predictable way. We measured self-localization using a mental ball dropping task and measured phenomenological aspects using a questionnaire. The results indicated that a significant variations in self-localization occurred during the experiment. As a follow-up study, we used mental imagery (in our case we used fMRI) to study the regions of the brain involved in this illusion

The out-of body experience: precipitating factors and neural correlates

Olaf Blanke, Silvia Bünning

Out-of-body experiences (OBEs) are defined as experiences in which a person seems to be awake and sees his body and the world from a location outside his physical body. More precisely, they can be defined by the presence of the following three phenomenological characteristics: (i) disembodiment (location of the self outside one's body); (ii) the impression of seeing the world from an elevated and distanced visuo-spatial perspective (extracorporeal, but egocentric visuo-spatial perspective); and (iii) the impression of seeing one's own body (autoscopy) from this perspective. OBEs have fascinated mankind from time immemorial and are abundant in folklore, mythology, and spiritual experiences of most ancient and modern societies. Here, we review some of the classical precipitating factors of OBEs such as sleep, drug abuse, and general anesthesia as well as their neurobiology and compare them with recent findings on neurological and neurocognitive mechanisms of OBEs. The reviewed data suggest that OBEs are due to functional disintegration of lower-level multisensory processing and abnormal higher-level self-processing at the temporo-parietal junction. We argue that the experimental investigation of the interactions between these multisensory and cognitive mechanisms in OBEs and related illusions in combination with neuroimaging and behavioral techniques might further our understanding of the central mechanisms of corporal awareness and self-consciousness much as previous research about the neural bases of complex body part illusions such as phantom limbs has done.

Elsevier2005

Flight of mind: Sensorimotor and multisensory embodiment with aviation robotics, flight simulator, and virtual reality

Myeong Seop Song

Normally, humans experience an 'I' as residing in one's body and as the agent of one's actions. In other words, the self is experienced as being inside the body (self-location), as having a body (self-identification), and as being able to control the person's body (agency). Over the last decade, research in cognitive neuroscience has revealed that vestibular signals contribute to such aspects of the embodied self. On the other hand, the influences of embodiment on vestibular sensations have received scant attention. In my thesis, I highlight how changes in multisensory and sensorimotor embodiment impact vestibular sensations. For this purpose, I merged technologies from photorealistic virtual reality (VR), aviation robotics such as a drone, flight simulator, haptics with knowledge of cognitive neuroscience about embodiment and bodily self-consciousness (BSC). The multidisciplinary approaches provide new paradigms to modulate embodiment and investigate related vestibular sensations based on multisensory and sensorimotor mechanisms of BSC. Also, the approaches reveal the relationship between embodiment and vestibular sensations. In Study 1, we have objectively shown the possibility of the duplication of the self by measuring peripersonal space (PPS). To this aim, we provided participants with real-time feedback from a drone-mounted camera that autonomously followed them while they responded to multisensory stimuli on their body and in their environment and walked forward. Our results demonstrate that this setup induces two spatially distinct PPSs in healthy participants: reaction times for visuotactile stimuli were faster around both the physical body and the observed body. In Studies 2 & 3, we have added a photorealistic avatar and a haptic vest to a robotic flight simulator to enable and investigate personalized immersive flight experiences in healthy humans. Study 2 showed that modulations of embodiment using sensorimotor stimulation resulted in enhanced subjective flying experience, better piloting performance, and learning. In Study 3, we showed that multisensory - visual and tactile - stimulation could further increase embodiment and improve piloting performance. Furthermore, in both studies, we found a positive relationship between embodiment and flight sensations. In Studies 4 & 5, we developed a new multisensory body scanning technology platform to induce and investigate one of the most common experiences in which the center of awareness is dissociated from the physical body: out-of-body experiences (OBEs). OBEs represent an interesting link between embodiment and vestibular sensations as they are characterized by embodiment of an elevated aerial position and perspective in space that is commonly associated with prominent sensations of floating, elevation, and flight. In this study, we have investigated how several sensorimotor and audio-visual stimulation conditions affect subjective sensations of disembodiment, floating, lightness as well as behavioral measures of self-location. In conclusion, my work developed new paradigms to investigate embodiment, BSC, and vestibular processing. My work revealed the influence of embodiment on vestibular sensations and applied these insights between embodiment and vestibular sensations to the field of field engineering by combining state-of-the-art technologies with knowledge of BSC with broad implications for robotics, neuroscience, of immersive VR, as well as experiential

EPFL2020

Self in time: imagined self-location influences neural activity related to mental time travel

Olaf Blanke

Conscious awareness of the self as continuous through time is attributed to the human ability to remember the past and to predict the future, a cogitation that has been called "mental time travel" (MTT). MTT allows one to re-experience one's own past by subjectively "locating" the self to a previously experienced place and time, or to pre-experience an event by locating the self into the future. Here, we used a novel behavioral paradigm in combination with evoked potential mapping and electrical neuroimaging, revealing that MTT is composed of two different cognitive processes: absolute MTT, which is the location of the self to different points in time (past, present, or future), and relative MTT, which is the location of one's self with respect to the experienced event (relative past and relative future). These processes recruit a network of brain areas in distinct time periods including the occipitotemporal, temporoparietal, and anteromedial temporal cortices. Our findings suggest that in addition to autobiographical memory processes, the cognitive mechanisms of MTT also involve mental imagery and self-location, and that relative MTT, but not absolute MTT, is more strongly directed to future prediction than to past recollection.

2008

Flight of mind: Sensorimotor and multisensory embodiment with aviation robotics, flight simulator, and virtual reality

Myeong Seop Song

EPFL2020