Self | EPFL Graph Search

In philosophy, the self is the relationship of an individual’s own being, knowledge and values. Self relates the experiences of one's inner and outer living in presence. The first-person perspective distinguishes selfhood from personal identity. Whereas "identity" is (literally) sameness and may involve categorization and labeling, selfhood implies a first-person perspective and suggests potential uniqueness. Conversely, "person" is used as a third-person reference. Personal identity can be impaired in late-stage Alzheimer's disease and in other neurodegenerative diseases. Finally, the self is distinguishable from "others". Including the distinction between sameness and otherness, the self versus other is a research topic in contemporary philosophy and contemporary phenomenology (see also psychological phenomenology), psychology, psychiatry, neurology, and neuroscience. Although subjective experience is central to selfhood, the privacy of this experience is only one of many problems

Wearable Haptics for Somatosensory Perception and Self-consciousness

Atena Fadaeijouybari

Recent research has highlighted the crucial role of the processing of somatosensory signals involving the torso for global aspects of Bodily Self Consciousness (BSC), i.e., the experience of the conscious "I" as embodied and localized within bodily space. Compared to advances in hand or finger-based haptic interfaces, current haptic technology for the torso is relatively underdeveloped as its operations are limited to stationary conditions and laboratory environments. My thesis aims to design, implement and validate novel torso-worn tactile displays to investigate BSC in healthy individuals with specific emphasis on robot-induced presence hallucination (PH, illusory experience of feeling someone behind) and tactile gait agency. First, I examined if torso-worn haptic interfaces can be used to induce specific alterations of BSC (passivity, self-touch, and PH) in healthy individuals by adapting a robotic system and paradigm previously established by our lab (Blanke et al. 2014) to the torso-worn haptic interface. In a feasibility study in healthy individuals, a torso-worn vibrotactile display (Study1) successfully induced the illusory sensations of being touched (passivity experience). Next, I developed CognoVest, a portable, torso-worn force interface that I designed to provide human-like poking stimuli on the user's back. Study 2 confirms the induction of illusory self-touch and passivity experiences by CognoVest and the induction of PH of mild to moderate intensity in healthy individuals. In Study 3, I extended the use of torso-worn haptic interfaces to the research on conscious action monitoring and investigated the sense of agency (SoA; a core aspect of BSC) for the entire body. To this aim, I developed the FeetBack system that examines the sensorimotor perception of tactile action consequences during locomotion, as previously tested by our lab for auditory and visual action consequences. Study 3 extends prior findings on the auditory or visual gait agency to the sense of touch and shows that delayed re-mapped tactile feedback systematically modulates SoA for walking. Finally, I examined and compared tactile spatial discrimination on the human back (Study 4) for force and vibrotactile stimulation, using interfaces realized in Study 2 and 3, thus providing a first direct (within-participant) evaluation of such interfaces. At the intersection of haptics and behavioral neuroscience, my thesis makes contributions by taking the first steps towards the design, and validation of torso-worn haptic interfaces as well as their applications in stationary/mobile sensorimotor experimentation settings. My findings for tactile perception on the back suggest that designers can use force stimulators to design the torso-worn tactile interface to provide more ecological touch feedback with an (almost) similar level of tactile spatial discrimination accuracy as observed in widespread vibrotactile interfaces. I applied this approach to the design of the CognoVest that induced systematic change in self-other distinctions. Results with CognoVest might have important implications for developing wearable therapeutic devices to down-regulate specific psychotic symptoms in patients with PH experiences. Moreover, I showed that healthy walkers had strong SoA for remapped tactile feedback, suggesting that the FeetBack system could potentially be used to enhance gait awareness in patients with gait deficits.

EPFL2021

Oligopotent stem cells are distributed throughout the mammalian ocular surface

Georges Abou Jaoudé, Yann Barrandon, Ariane Rochat

The integrity of the cornea, the most anterior part of the eye, is indispensable for vision. Forty- five million individuals worldwide are bilaterally blind and another 135 million have severely impaired vision in both eyes because of loss of corneal transparency(1); treatments range from local medications to corneal transplants, and more recently to stem cell therapy(2). The corneal epithelium is a squamous epithelium that is constantly renewing, with a vertical turnover of 7 to 14 days in many mammals(3). Identification of slow cycling cells ( label- retaining cells) in the limbus of the mouse has led to the notion that the limbus is the niche for the stem cells responsible for the long- term renewal of the cornea(4); hence, the corneal epithelium is supposedly renewed by cells generated at and migrating from the limbus, in marked opposition to other squamous epithelia in which each resident stem cell has in charge a limited area of epithelium(5,6). Here we show that the corneal epithelium of the mouse can be serially transplanted, is self- maintained and contains oligopotent stem cells with the capacity to generate goblet cells if provided with a conjunctival environment. Furthermore, the entire ocular surface of the pig, including the cornea, contains oligopotent stem cells (holoclones)(7,8) with the capacity to generate individual colonies of corneal and conjunctival cells. Therefore, the limbus is not the only niche for corneal stem cells and corneal renewal is not different from other squamous epithelia. We propose a model that unifies our observations with the literature and explains why the limbal region is enriched in stem cells.

2008

Dissecting self-voice perception: From bone conduction to robotically-induced self-other voice misattribution in healthy listeners

Pavo Orepic

Inspired by the prominent theory suggesting that auditory-verbal hallucinations (AVH) - the sensation of hearing voices without present speakers - arise as misattribution of inner speech towards external agents, my thesis revolved around self-voice perception and the experimental attempts of self-other voice misattribution in a healthy, non-hallucinating population, potentially mimicking the AVH phenomenology. In the first part of my thesis, I investigated behavioral (Study 1) and neural (Study 2) underpinnings of self-other voice discrimination (SOVD). Compared to other self-related processes, self-voice perception has been investigated to a surprisingly lesser extent. Namely, self-voice research has been thwarted by the inability to experimentally match self-voice recordings to the natural sound of our voice that is altered by bone conduction. In a series of five experiments, I showed that this discrepancy can be reduced by presenting self-voice stimuli through a commercial bone conduction headset, thereby rendering self-voice as an essentially multi-modal construct. My data further shows that self-voice recognition differs from the recognition of familiar voices, however, that it still involves some familiarity processing. In addition, I explored the roles other-voice familiarity and acoustic similarity to other voice play in SOVD. Finally, I identified a self-voice specific EEG pattern, around 345 milliseconds after stimulus onset, that followed the initial auditory cortex activation, discriminated the self-voice from the voice of another unfamiliar person, and activated an extended network involving the cingulate cortex, insula, and medial temporal lobe structures. Moreover, this network was recruited less frequently with self-voices presented through bone conduction, and the occurrence of the network negatively correlated with SOVD task performance. Based on these methodological, behavioral, and neural findings in SOVD, in the second part of my thesis, I tried to experimentally induce specific misattributions of self-towards-other voices, following the prominent theory linking AVH with self-monitoring deficits. In order to do so, I combined the aforementioned SOVD task with a robotic procedure able to engender mild hallucinations in healthy individuals by perturbing bodily self-monitoring mechanisms. With such a procedure, I managed to alter self-voice perception of healthy participants (Study 3), what I further related to breathing (Study 4). Finally, I managed to induce identity-specific AVH in healthy individuals (Study 5), as quantified by the false alarm rate in a voice detection task, thereby contributing to the understanding of the mechanisms underlying AVH and relating them to impairments in bodily self-monitoring. Laying at the intersection of three sub-fields of neuroscience - voice perception, self-processing, and psychiatry - my thesis made a contribution by identifying neural correlates of SOVD, by proposing a new, multimodal perspective on self-voice-related research questions, and by demonstrating an experimental method of inducing AVH in a controlled laboratory environment. Together, my findings shed new light on the interactions between self-voice perception, sensorimotor processing, and interoception.

EPFL2020