Cognitive neuroprosthetics for investigating and restoring body perception

Our brain constantly receives and integrates a flow of multisensory bodily inputs that are responsible for the way our body is represented and consciously experienced. However, in some pathological conditions, patients might experience altered perceptions of their body or suffer from abnormal bodily sensations such as chronic pain. Recent studies in cognitive neuroscience demonstrate that it is possible to modulate bodily self-consciousness and related bodily experiences by experimentally manipulating multisensory bodily inputs. Using such approaches, this work aims to investigate abnormal body experiences and to develop new therapeutic solutions for patients suffering from distorted body representation and chronic pain. First, we manipulated visuo-tactile information to investigate alterations of bodily self-consciousness in spinal cord injured patients and demonstrated the potential analgesic effects of such multisensory stimulation (Study 1). Then, we combined neuro-tactile stimulation with visual stimulation via virtual reality in amputees to induce embodiment for their prosthetic hands, and to improve abnormal phantom limb perceptions (Study 2). We then used a similar approach in patients with chronic leg pain and combined spinal cord stimulation with visual stimulation via virtual reality to in-crease analgesia induced by neuromodulation (Study 3). In another series of studies, we investigated the role of inter-oceptive signals in chronic pain. First, we demonstrated that patients suffering from complex regional pain syndrome (CRPS) had reduced abilities in perceiving and processing their heartbeat (Study 4). Then, we manipulated interocep-tive information with visual stimulation via virtual reality to reduced CRPS symptoms (Study 5). Collectively, these five studies demonstrate the possibility to use the latest research on the neuroscience of embodi-ment and virtual technology to study disorders of body representation. Furthermore we aim to develop new cognitive neuroprosthetic approaches including restoring normal body perception, inducing embodiment for a prosthetic limb, and alleviating chronic pain.

Multisensory and sensorimotor origins of the sense of self

Polona Pozeg

Cognitive neuroscience has increasingly focused on studying the subject, i.e. the self, of conscious experience. In order to be the subject of an experience, we generally experience owning a physical body, being located within that body, and being able to distinguish the body and its actions from others. These pre-reflective experiences are based on brain mechanisms of multisensory and sensorimotor integration. In this thesis I investigated how our sense of self, in particular the senses of body ownership and of agency, depend on multimodal bodily signals. I achieved this by using approaches developed by cognitive neuroscience to study how the sense of self relates to the processing of bodily signals: creating bodily illusions with multisensory conflicts through the use of virtual reality and robotics. The first part of this thesis describes the investigation of the sense of body ownership in healthy subjects and in spinal cord injury patients, achieved by inducing conflicts between tactile information and visual feedback. The research presented in the second part of the thesis is centered on the experience of self-touch. There, I have first investigated how the manipulation of reference frames influences the perception of the illusion of self-touch, and second, how active self-touch influences the sense of body ownership. Lastly, in the third part of the thesis, I investigated how experimentally induced multisensory and sensorimotor conflicts perturb the sense of self in healthy subjects and induce experiences similar to certain symptoms observed in neurological and psychiatric disorders. I show that particular conflicts between bodily signals not only affect body perception and sense of agency for motor actions but also propagate to higher levels and influence even the sense of agency for mental representations in healthy subjects. Finally, I discuss my results and their relation to existing knowledge on bodily self-consciousness and position them in a broader picture of our current understanding of the self.

EPFL2016

Distinct illusory own-body perceptions caused by damage to posterior insula and extrastriate cortex

Olaf Blanke, Lukas Heydrich

Recent research in cognitive neuroscience using virtual reality, robotic technology and brain imaging has linked self-consciousness to the processing and integration of multisensory bodily signals. This work on bodily self-consciousness has implicated the temporo-parietal, premotor and extrastriate cortex and partly originated in work on neurological patients with different disorders of bodily self-consciousness. One class of such disorders is autoscopic phenomena, which are defined as illusory own-body perceptions, during which patients experience the visual illusory reduplication of their own body in extrapersonal space. Three main forms of autoscopic phenomena have been defined. During autoscopic hallucinations, a second own body is seen without any changes in bodily self-consciousness. During out-of-body experiences, the second own body is seen from an elevated perspective and location associated with disembodiment. During heautoscopy, subjects report strong self-identification with the second own body, often associated with the experience of existing at and perceiving the world from two places at the same time. Although it has been proposed that each autoscopic phenomenon is associated with different impairments of bodily self-consciousness, past research on neurological patients and the development of experimental paradigms for the study of bodily self-consciousness has focused on out-of-body experiences and the association with temporo-parietal cortex. Here, we performed quantitative lesion analysis in the-to date-largest group of patients with autoscopic hallucination and heautoscopy and compared the location of brain damage with those of control patients suffering from complex visual hallucinations. We found that heautoscopy was associated with lesions to the left posterior insula, and that autoscopic hallucinations were associated with damage to the right occipital cortex. Autoscopic hallucination and heautoscopy were further associated with distinct symptoms and deficits. The present data suggest that the autoscopic hallucination is a visuo-somatosensory deficit implicating extrastriate cortex and is, despite the visual hallucination of the own body, not associated with major deficits in bodily self-consciousness. Based on the symptoms and deficits in patients with heautoscopy and the implication of the left posterior insula, we suggest that abnormal bodily self-consciousness during heautoscopy is caused by a breakdown of self-other discrimination regarding affective somatosensory experience due to a disintegration of visuo-somatosensory signals with emotional (and/or interoceptive) bodily signals. These brain mechanisms are distinct from those described for out-of-body experiences. The present data extend previous models of autoscopic phenomena and provide clinical evidence for the importance of emotional and interoceptive signal processing in the posterior insula in relation to bodily self-consciousness.

2013

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