No description available.

La mémoire autobiographique est vue comme un ensemble d'informations et de souvenirs personnels permettant de construire un sentiment d'identité. Elle se développe progressivement et apparaît très sensible aux pathologies neurodéveloppementales. La mémoire autobiographique est intimement liée au Soi lui permettant d'encoder et de récupérer toutes ses représentations et expériences. Ainsi, le Soi se constitue d'aspects explicites comprenant la mémoire autobiographique mais également d'aspects plus implicites relatifs aux expériences corporelles du sujet. L'atteinte des aspects implicites et explicites du Soi pourrait rendre compte de certains symptômes psychotiques et des difficultés d'adaptation des patients atteints de schizophrénie. La schizophrénie est une pathologie neurodéveloppementale qui débute à la fin de l'adolescence mais qui pourrait puiser son émergence dans des stades bien plus précoces. Le premier épisode psychotique qui signe l'entrée dans la phase active de la maladie est généralement précédé par une phase « prodromique » où des symptômes cliniques sont présents à un niveau infraliminaire du seuil de psychose. Ces sujets sont qualifiés de sujets à ultra haut risque de psychose (UHR). Les troubles du Soi sont bien documentés dans la schizophrénie, néanmoins très peu de données sont disponibles concernant les sujets UHR. Le but de cette thèse est multiple : (i) mesurer l'impact des anomalies neurodéveloppementales sur la mémoire autobiographique, (ii) objectiver des déficits de la mémoire autobiographique dès la phase prodromique, (iii) évaluer l'ensemble des composantes du Soi afin d'investiguer leurs interactions et l'impact des anomalies développementales sur celles-ci. Nous avons ainsi effectué trois études. Notre première étude a investigué le lien entre le poids des anomalies neurodéveloppementales et la mémoire autobiographique en comparant deux pathologies neurodéveloppementales, une à début tardif : la schizophrénie, et l'autre à début précoce : les troubles du spectre autistique. Nous avons pu mettre en évidence un pattern de performances similaires entre les deux populations bien que les mécanismes responsables des troubles en mémoire autobiographique apparaissent distincts. Dans notre deuxième étude, nous avons comparé les performances autobiographiques de patients atteints de schizophrénie par rapport à celles de sujets UHR. Nos résultats révèlent un déficit de la mémoire autobiographique aussi sévère chez les sujets UHR que chez les patients atteints de schizophrénie mettant ainsi en évidence une atteinte de cette fonction en amont du premier épisode psychotique. Dans la lignée de ces résultats, nous avons conduit une troisième étude. Le but étant de situer la mémoire autobiographique dans un contexte plus large, celui du Soi, tout en intégrant une composante développementale. Nous avons élaboré et proposé une batterie d'investigation examinant différents aspects du Soi implicites et explicites, combiné à l'évaluation d'anomalies du neurodéveloppement. Celle-ci a été administrée chez des sujets UHR en comparaison à des patients atteints de schizophrénie. Au final, nos résultats révèlent un impact de la charge neurodéveloppementale sur les différents aspects du Soi, la pertinence d'investiguer au sein d'un même protocole ces différents aspects et la présence d'anomalies du Soi déjà présents chez les sujets UHR, constituant potentiellement des marqueurs prédicteurs de transition psychotique et permettant d'améliorer la détection précoce de ces sujets et leur prise en charge. / Autobiographical memory is delineated as a set of personal information and experiences to build a sense of identity. It develops gradually and appears very sensitive to neurodevelopmental disorders. Autobiographical memory is intimately linked to the self, enabling it to encode and retrieve all its representations and experiences. Thus, the self is constituted of explicit aspects including autobiographical memory but also by more implicit aspects relating to the subject's body. Implicit and explicit self-aspects alterations may account for certain psychotic symptoms and adaptation difficulties in patients with schizophrenia. Schizophrenia is a neurodevelopmental disorder that begins at the end of adolescence but which could emerge in much earlier stages. The first psychotic episode that signs the beginning of the active phase of schizophrenia is usually preceded by a "prodromal phase" during which clinical signs are present at a sub-threshold level. Individuals experiencing these signs are considering as Ultra High Risk of psychosis (UHR). Self-disorders are well documented in schizophrenia, however very little is known regarding UHR subjects. The aim of this thesis is multiple: (i) to measure the impact of neurodevelopmental anomalies on autobiographical memory, (ii) to objectify autobiographical memory deficits in the prodromal phase, (iii) to evaluate all the self-components in order to investigate their interactions and the impact of developmental anomalies. We have conducted three studies. Our first study investigated the relationship between neurodevelopmental anomalies and autobiographical memory by comparing two neurodevelopmental disorders, one with late onset: schizophrenia and the other with early onset: autism spectrum disorders. Results revealed a pattern of similar performances between the two populations although the mechanisms responsible for autobiographical memory impairment do not appear the same. In our second study, we compared the autobiographical performances of patients with schizophrenia compared to those of UHR subjects. Our results highlighted a deficit of autobiographical memory as severe in UHR subjects as in patients with schizophrenia, thus revealing an impairment of this function upstream of the first psychotic episode. In line with these results, we conducted a third study. The aim was to situate the autobiographical memory in a wider context, the multi-componential Self, while integrating a developmental component. We developed and proposed a battery investigating different self-components, combined with the assessment of neurodevelopmental anomalies. This battery was administered in UHR subjects compared to patients with schizophrenia. Finally, our results reveal an impact of neurodevelopmental abnormalities on the different self-aspects, the relevance of investigating these different self-aspects within the same protocol and the presence of self-abnormalities already present in the UHR subjects, constituting potentially predictive marker of psychotic transition and improving the early detection of these subjects and the development of healthcare and reinsertion programs.

The distinction between the sense of body-ownership and the sense of agency has attracted considerable empirical and theoretical interest lately. However, the respective contributions of multisensory and sensorimotor integration to these two varieties of body experience are still the subject of ongoing research. In this study, I examine the various methodological problems encountered in the empirical study of body-ownership and agency with the use of novel immersive virtual environment technology to investigate the interplay between sensory and motor information. More specifically, the focus is on testing the relative contributions and possible interactions of visual-tactile and visual-motor contingencies implemented under the same experimental protocol. The effect of this is supported by physiological measurements obtained from skin conductance responses and heart rate. The findings outline a relatively simple method for identifying the necessary and sufficient conditions for the experience of body-ownership and agency, as studied with immersive virtual environment technology.

京都大学 / 0048 / 新制・課程博士 / 博士(人間健康科学) / 甲第22650号 / 人健博第77号 / 新制||人健||5(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 稲富 宏之, 教授 青山 朋樹, 教授 髙橋 良輔 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM

The feeling of owning a body part is often investigated by conducting and manipulating the rubber hand illusion, a three-way integration of vision, touch, and proprioception. In the last decade, more research on the role of interoception, the sense of the body's’ internal state, in the illusion has been made. One of the studied factors has been the affective touch, a caress-like, gentle, touch that is performed at a slow specific speed (1-10 cm/sec). Affective touch activates the C tactile afferents which send interoceptive signals to the brain, specifically the insula. The present systematic review investigated the role affective touch has on the strength of the rubber hand illusion. A range of electronic databases was searched for papers reporting research findings published in English before March 20, 2020. Twelve different articles were identified, but only five papers met the inclusion criteria. This thesis looked at the results from these five different studies and compared the effect of affective touch and discriminative, regular, touch have on the rubber hand illusion to see whether there is a significant difference. The results could not show a main effect of stroking velocity, site of stimulation, or social touch, which are components of affective touch. The results was based on four different measurements, the subjective experience of the illusion, pleasantness ratings, proprioceptive drift, and temperature difference in the skin. Opposed what was hypothesized, it could not be demonstrated that affective touch would induce a stronger rubber hand illusion than discriminative touch.

How is it that we feel that we own our body? And how does the brain create this feeling? By manipulating the integration of multisensory signals, researchers have recently begun to probe this question. By creating the illusory experience of owning external body-parts and entire bodies, researchers have investigated the neurofunctional correlates of body ownership. Recent attempts to quantitatively synthesize the neuroimaging literature of body ownership have shown inconsistent results. A large proportion of functional magnetic resonance imaging (fMRI) findings on body ownership includes region of interest (ROI) analysis. This analysis approach produces inflated findings when results are synthesized in meta-analyses. We conducted a systematic search of the fMRI literature of ownership of body-parts and entire bodies. Two activation likelihood estimation (ALE) meta-analyses were conducted, testing the impact of including ROI-based findings. When ROI-based results were included, frontal and posterior parietal multisensory areas were associated with body ownership. However, a whole-brain meta-analysis, excluding ROI-based results, found no significant convergence of activation across the brain. These findings highlight the difficulty of quantitatively synthesizing a neuroimaging field where a large part of the literature is based on findings from ROI analysis. We discuss the difficulty of quantitatively synthesizing results based on ROI analysis and suggest future directions for the study of body ownership within the field of cognitive neuroscience.

Body ownership can be studied via the rubber hand illusion (RHI), in which an artificial limb can be perceived as belonging to oneself. In the so-called moving RHI paradigm, both body ownership and sense of agency, induced by self-produced movements, can be investigated. The key question of this approach is whether movements generated by oneself increase the illusion of body ownership. Thus far, the results from moving RHI studies are inconsistent.This has led to uncertainty regarding the influences of the motor control mechanism on body ownership. Therefore, this study will present the first meta-analysis on moving RHI to estimate the illusory effectiveness induced by self-produced movements. A total of 23 experimental comparisons with 821 subjects were included in the meta-analysis. The results showed that the overall illusory effect induced by self-produced movements was superior toits control (e.g., asynchronous active movements) (Hedge’s g = 1.38, p < 0.001). However, due to dissimilarity in results between the studies, the sample size in the meta-analysis may not represent the general population. The subgroup analysis showed that studies using physical hands, such as wooden hands, yielded the largest effect compared to studies using a virtual projected hand or a video recorded image of the participant’s own hands. It can be speculated whether a three-dimensional hand with “realness” has an illusory advantage compared to hands presented in virtual or video image settings. Future studies need to apply aunified framework, particularly in experimental setups and measurements. This would obtain consistent results of the strength of the illusion within the moving RHI paradigm.

Body ownership is a complicated and multifaceted percept. Although we subjectively perceive body ownership to be a stable component of our identity, recent work has illustrated that body ownership is a dynamic construct that is constantly updated by the integration of current endogenous and exogenous body-related information. The goal of this study was to explore the relation between these endogenous (interoceptive) and exogenous (exteroceptive) channels of information. We investigated this by using a heartbeat perception (HBP) task to measure interoceptive accuracy, and the Rubber Hand Illusion (RHI) to measure malleability of body ownership. Based on prior findings, we hypothesized that the less accurate you are at counting your heartbeats, the more susceptible you will be to the RHI (i.e. the more malleable your sense of body ownership will be). In addition, we were also interested in exploring the relationship between interoception and emotion recognition ability (ERA). In this experiment, we failed to induce the RHI, and thus could not investigate the relationship between endogenous and exogenous body-related information. However, we successfully demonstrated the reliability of the interoceptive accuracy HBP task, as well as demonstrated that interoceptive accuracy is not related to ERA. / Thesis / Master of Science (MSc)

Our bodies are arguably one of the most intimate things we will ever know. But the comfort of our own physical boundaries can be altered in various ways. In this analysis, we will look at how vision contributes to the sense of owning a body by analysing six abnormal conditions: the rubber hand illusion, phantom limbs, somatoparaphrenia, the body-swap illusion, out-of-body experiences, and heautoscopy. Examinations of these experimental or pathological conditions has granted a greater understanding of body-ownership. It was discovered that vision plays different modulatory roles, being more intricately involved in full-body ownership than in part-body ownership. Vision appears to be highly connected to self-location and first-person perspective, which both are contributing factors in projecting the sense of ownership to an external location. In part-body ownership, however, vision can be overruled by other senses, such as proprioception. Though it is still able to contribute to the illusion of projecting ownership and proprioceptive displacement to a rubber hand.

In the last decade, neuroscience and psychology alike have paid increasing attention to the study of affective touch, which refers to the emotional and motivational facets of tactile sensation. Some aspects of affective touch have been linked to a neurophysiologically specialised system, namely the C tactile (CT) system. While the role of this system for affiliation, social bonding and communication of emotions have been investigated, less is known about the potential role of affective touch in the awareness of the body as our own, i.e. as belonging to our psychological 'self'. This thesis attempted to contribute to the knowledge on affective touch and its relation to body awareness, by exploring the potential role of this modality to the way we perceive and make sense of our body as our own. Specifically, this work aimed to advance the current state of knowledge by investigating: 1) the effect of affective touch on the sense of body ownership, which is a fundamental aspect of body awareness; 2) the relation between interoceptive modalities, originating both internally (i.e. cardiac awareness) and peripherally (i.e. affective touch), and exteroception in body awareness; 3) the effect of intranasal oxytocin on the perception of affective touch and bodily awareness; 4) the perception and social modulation of affective touch in psychiatric patients who show difficulties in body awareness, namely patients with Anorexia Nervosa, and 5) the modulating role of self-other distinction and of self-other relation in the perception of affective touch and body awareness. In a first experiment (N = 52) the rubber hand illusion paradigm was used to investigate the role played by CT-optimal, affective touch in the sense of body ownership. The results showed that slow, pleasant touch enhanced the experience of embodiment in comparison to faster, neutral touch, suggesting that affective touch might uniquely contribute to the sense of body ownership. The following study (N = 75), used a similar methodology to test whether interoceptive sensitivity as measured by a heartbeat counting task would modulate the extent to which affective touch influences the multisensory process taking place during the rubber hand illusion. The results could not confirm a systematic relation between interoceptive sensitivity and the perception of affective touch, nor its influence on body ownership. The next study (N = 41) included a double-blind, placebo-controlled, randomised, cross-over design testing the effect of intranasal oxytocin on the perception of affective touch and body ownership, as measured by means of the rubber hand illusion. There was no evidence supporting the hypothesis that intranasal oxytocin could influence the CT system as tested in this study. The next study (N = 55) applied some of the above methodologies to investigate the perception of CT-optimal touch in patients with anorexia nervosa and its emotional modulation by top-down factors. The results confirmed the hypothesis that people with anorexia nervosa show a reduced perception of affective touch compared to healthy controls, but its perception was not influenced by top-down affective modulation, in the sense that both patients and healthy controls perceived touch as more pleasant when presented concurrently with positive facial expressions compared to neutral and negative faces. Finally, the last two studies (N = 76 and 35 healthy volunteers, respectively) focused on the relationship between affective touch and body awareness in the context of social cognition. These studies used both online and offline social modulation paradigms to investigate the role of self-other distinction and of self-other relation in the perception of affective touch. The results showed that positive top-down social information can enhance the perceived pleasure of tactile stimulation. Taken together, these studies point to the central role of affective touch in body awareness and social cognition. Finally, they also pave the way for future studies examining the role of disruptions of the CT system in the development of neuropsychiatric impairments of body awareness and social cognition.