Vestibular system | EPFL Graph Search

The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals. As movements consist of rotations and translations, the vestibular system comprises two components: the semicircular canals, which indicate rotational movements; and the otoliths, which indicate linear accelerations. The vestibular system sends signals primarily to the neural structures that control eye movement; these provide the anatomical basis of the vestibulo-ocular reflex, which is required for clear vision. Signals are also sent to the muscles that keep an animal upright and in general control posture; these provide the anatomical means required to enable an animal to maintain its desired position in space. The brain uses information from the vestibular system in the head and from propri

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

Vestibular contribution to bodily self-consciousness and multisensory cortical processing

Christian Pfeiffer

How does the self relate to the body? Bodily self-consciousness, i.e. the sense of being a subject bound to a body, involves a first-person perspective (1PP), i.e. the sense of being directed at the world. Prior research suggests that bodily self-consciousness depends on brain mechanisms integrating multisensory bodily signals. However, the specific multisensory mechanisms of 1PP are poorly understood. Here, I defend the thesis that the vestibular system, i.e. the sensory system encoding rotational and linear accelerations of the head, contributes to 1PP and related multisensory processing in the brain. The first part of my thesis presents experimental evidence showing that 1PP was influenced by multisensory conflict about the direction of gravity and the location of the body. 1PP depended on integrated visual-vestibular signals and was functionally distinct from another aspect of bodily self-consciousness: self-identification, i.e. the feeling that a particular body is âmineâ. The second part of my thesis presents the electrical neural correlates by which vestibular stimulation affected somatosensory and visual cortical processing. Passive whole-body yaw rotation naturally and selectively stimulated the vestibular system while the evoked responses to somatosensory or visual stimuli were recorded by electroencephalography. Electrical neuroimaging analysis showed temporal-specific vestibular effects on somatosensory and visual evoked potentials, localized by source estimations to distinct regions of the somatosensory, visual, and vestibular cortical networks. Collectively, the results from my thesis suggest that the vestibular system contributes to 1PP and multisensory cortical processing and imply that the vestibular system should not be neglected when studying higher brain function and neurobiological mechanisms of consciousness.

EPFL2015

Multisensory Spatial Mechanisms of the Bodily Self and Social Cognition - A Commentary on Vittorio Gallese and Valentina Cuccio

Christian Pfeiffer

This commentary aims to find the right description of the pre-reflective brain mechanisms underlying our phenomenal experience of being a subject bound to a physical body (bodily self) and basic cognitive, perceptual, and subjective aspects related to interaction with other individuals (social cognition). I will focus on the proposal by Gallese and Cuccio that embodied simulation, in terms of motor resonance, is the primary brain mechanism underlying the pre-reflective aspects of social cognition and the bodily self. I will argue that this proposal is too narrow to serve a unified theory of the neurobiological mechanisms of both target phenomena. I support this criticism with theoretical considerations and empirical evidence suggesting that multisensory spatial processing, which is distinct from but a pre-requisite of motor resonance, substantially contributes to the bodily self and social cognition. My commentary is structured in three sections. The first section addresses social cognition and compares embodied simulation to an alternative account, namely the attention schema theory. According to this theory we pre-reflectively empathize with others by predicting their current state of attention which involves predicting the spatial focus of attention. Thereby we derive a representational model of their state of mind. On this account, spatial coding of attention, rather than motor resonance, is the primary mechanism underlying social cognition. I take this as a theoretical alternative complementing motor resonance mechanisms. The second section focuses on the bodily self. Comparison of the brain net- works of the bodily self and social cognition reveals strong overlap, suggesting that both phenomena depend on shared multisensory and sensorimotor mechanisms. I will review recent empirical data about altered states of the bodily self in terms of self-location and the first-person perspective. These spatial aspects of the bodily self are encoded in brain regions distinct from the brain network of em- bodied simulation. I argue that while motor resonance might contribute to body ownership and agency, it does not account for spatial aspects of the bodily self. Thus, embodied simulation appears to be a necessary but insufficiently “primary” brain mechanism of the bodily self and social cognition. The third section discusses the contributions of the vestibular system, i.e., the sensory system encoding head motion and gravity, to the bodily self and social cognition. Vestibular cortical processing seems relevant to both processes, be- cause it directly encodes the world-centered direction of gravity and allows us to distinguish between motions of the own body and motions of other individuals and the external world. Furthermore, the vestibular cortical network largely overlaps with those neural networks relevant to the bodily self and social cognition. Thus, the vestibular system may play a crucial role in multisensory spatial coding relating the bodily self to other individuals in the external world.

2015

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

Myeong Seop Song

EPFL2020

Multisensory Spatial Mechanisms of the Bodily Self and Social Cognition - A Commentary on Vittorio Gallese and Valentina Cuccio

Christian Pfeiffer

2015