What is the body schema?

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À l'origine de la conscience corporelle : les représentations du corps à la lumière de la clinique

Les travaux sur la conscience du corps propre se sont multipliés au cours des dernières décennies. Le concept de représentation corporelle en particulier a gagné en importance. On suppose généralement que deux principales représentations corporelles se distinguent : l'image corporelle et le schéma corporel. La première sous-tend la perception du corps propre ; la seconde le contrôle de l’action. Dans cette thèse, j'étudie les représentations corporelles conceptuellement et empiriquement à la lumière des expériences corporelles rapportées par les patients souffrant de troubles neurologiques et psychiatriques. Je me concentre sur trois questions principales. Premièrement, au-delà des différences entre le schéma et l'image corporels, quels sont leurs modes d’interactions ? La proposition est que le schéma et l’image corporels ne sont pas totalement indépendants. Au contraire, ils sont en constante interaction et se remodèlent l’un l’autre. Il est donc postulé un modèle de co-construction du schéma et de l’image corporels, dans lequel le schéma corporel pourrait avoir une certaine primauté sur l'image corporelle, le premier précédant et fondant la construction de la seconde. Dans une seconde partie de ce travail, je me tourne vers la prise de conscience de l’intérieur du corps. Comment les expériences des organes internes sont-elles représentées ? La question a été largement ignorée dans la littérature sur les représentations corporelles. Ici, il est proposé qu'une représentation spécifique structure la conscience de l’intérieur du corps. La construction de cette « carte de corps intérieur » repose principalement sur des informations contextuelles sur le corps, se distinguant ainsi du schéma corporel et de l'image corporelle dont la construction repose davantage sur des signaux sensoriels. Les distorsions de la carte de corps intérieur peuvent expliquer des troubles de la conscience de l’intérieur du corps, en particulier des symptômes somatiques persistants qui ne reposent pas sur une lésion ou un dysfonctionnement du corps. La dernière question de cette thèse concerne la manière dont les représentations corporelles s'adaptent dans le temps. Parfois, il semble que le rôle des représentations corporelles est de suppléer les signaux sensoriels manquants, assurant ainsi la cohérence et la stabilité de la conscience corporelle dans le temps. À l'inverse, dans d'autres cas, il semble que le contenu des représentations corporelles change rapidement comme dans les hallucinations corporelles lors desquelles les patients ressentent soudainement leur corps avec une taille et une forme anormale. Par quoi l'adaptabilité des représentations corporelles est-elle sous-tendue ? Un mécanisme putatif est étudié ici, à savoir les signaux provenant des battements cardiaques. Dans deux expériences comportementales, il est montré que les actions sont mieux exécutées en synchronisation avec les battements du coeur, suggérant ainsi des relations étroites entre le corps intérieur et extérieur pour encoder l’adaptabilité de la perception corporelle. Au total, les travaux compilés dans cette thèse ouvrent de nouvelles voies pour mieux comprendre les représentations corporelles à la lumière des expériences des patients.Investigations about the awareness of one’s own body have bloomed in the last decades. In particular, the concept of body representations has gained much emphasis. It is generally assumed that two main body representations separate: the body image and the body schema. The former body representation underlies the perception of one’s own body; the latter underlies action control. In this thesis, I theoretically and empirically investigate body representations in light of distorted bodily experiences of patients with neurological and psychiatric disorders. I focus on three main questions. Firstly, beyond the differences between the body schema and the body image, what are their ways of interactions? The proposal is that the two representations are not independent. On the contrary, they are in constant interplay partly reshaping each other. It is therefore postulated a co-constructed model of the body image and the body schema. Furthermore, the body schema might have some primacy over the body image, the former preceding and grounding the shaping of the latter. In a second part of this work, I turn to the awareness of the internal body. How are experiences about one’s own organs represented? The question has been largely overlooked in the literature on body representations. Here, it is proposed that a specific inner body map structures the awareness of the internal body. More, the construction of the inner body map mostly relies on prior information about of the body, thereby distinguishing from the body schema and the body image whose construct relies more on sensory cues. Distortions of the inner body map can explain disorders of the awareness of the internal body, in particular persistent physical symptoms that do not rely on a lesion or malfunction of the body. The last question of this thesis is concerned by how body representations adapt in time. Sometimes, it seems that the role of body representations is to stand for missing sensory inputs from the body, thereby ensuring the coherence and the stability of bodily awareness over time. Conversely, in other cases it seems that the content of body representations changes quickly as in bodily hallucinations in which patients feel suddenly their own body with a different size and shape. How is the adaptiveness of body representations encoded? One putative underlying mechanism might relate to signals from one’s own heartbeats. Here we go one step further. Across two behavioral experiments, it is shown that the decision whether to act or not is better performed in synchrony with heartbeats, further advocating for close relations between the internal and the external body. Overall, the work compiled in this thesis opens new avenues for further investigating body representations in light of patients’ distorted bodily experiences

How do the body schema and the body image interact?

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Sleep in times of pandemic. Lessons for the management of insomnia

International audience"Sleep in times Of pandemic: lessons for the Management of insomnia. Sleep is both a determinant of health and a valuable Indicator of psychological impact in both personal and Global crisis situations. Results from the coconel (coronavirus. Containment longitudinal study) surveys, Conducted in the aftermath of the first 2020 sars-cov-2 Pandemic containment, show a significant increase in Sleep disturbance compared to previous data: significantly Increased prevalence compared to 2017 in women (from 66% to 81%) and even more in men (from 42% to 66%). Young people were particularly affected as well as economically Vulnerable people. The percentage of French People reporting regular use of hypnotics almost doubled (from 9% to 17%). Simple sleep hygiene rules can be provided to better cope With these periods of pandemic, stress and isolation. Thanks to the data acquired, these recommendations Could be refined, including the significant impact of Media exposure, a new prevention issu

Polysomnographic parameters in long-COVID chronic insomnia patients

While COVID-19 is predominantly considered to be an acute self-remitting disease, it has been pointed out that a variety of symptoms can linger for several months, a phenomenon identified as long-COVID. Insomnia is particularly prevalent in long-COVID. In the present study, we aimed at confirming and characterising insomnia in long-COVID patients through polysomnography and to identify whether its parameters differ from patients with chronic insomnia and no long-COVID history

Nature and determinants of social actions during a mass shooting

International audienceReactions to danger have been depicted as antisocial but research has shown that supportive behaviors (e.g., helping injured others, giving information or reassuring others) prevail in life-threatening circumstances. Why is it so? Previous accounts have put the emphasis on the role of psychosocial factors, such as the maintenance of social norms or the degree of identification between hostages. Other determinants, such as the possibility to escape and distance to danger may also greatly contribute to shaping people's reactions to deadly danger. To examine the role of those specific physical constraints, we interviewed 32 survivors of the attacks at 'Le Bataclan' (on the evening of 13-11-2015 in Paris, France). Consistent with previous findings, supportive behaviors were frequently reported. We also found that impossibility to egress, minimal protection from danger and interpersonal closeness with other crowd members were associated with higher report of supportive behaviors. As we delved into the motives behind reported supportive behaviors, we found that they were mostly described as manifesting cooperative (benefits for both interactants) or altruistic (benefits for other(s) at cost for oneself) tendencies, rather than individualistic (benefits for oneself at cost for other(s)) ones. Our results show that supportive behaviors occur during mass shootings, particularly if people cannot escape, are under minimal protection from the danger, and feel interpersonal closeness with others. Crucially, supportive behaviors underpin a diversity of motives. This last finding calls for a clear-cut distinction between the social strategies people use when exposed to deadly danger, and the psychological motivations underlying them

Nature and determinants of social actions during a mass shooting

If collective reactions to danger have long been portrayed as antisocial and self-preservative, research has shown that prosociality is maintained and sometimes fostered in life-threatening circumstances. In this research, we interviewed 32 survivors of the attacks at ‘Le Bataclan’ (on the evening of 13-11-2015 in Paris, France) with the aims of offering a typology of social behaviors undertaken in the context of a mass shooting in a close environment, and examining the situational factors favoring the emergence of socially supportive behaviors among hostages. Consistent with previous findings, we found that socially supportive behaviors were frequently reported, and they were more common than socially unsupportive behaviors in the narratives of the respondents. We also found that the occurrence of socially supportive actions is dependent on key contextual factors, namely the impossibility to egress, increased distance and/or minimal protection from the source of danger, and emotional fusion with other crowd members. Finally, although supportive behaviors can be served by a variety of motives (individualistic, cooperative or altruistic), we found that supportive actions were more often described by respondents as reflecting genuine altruism, i.e. involving a cost to oneself at the benefit of others. Those results bring evidence of the maintenance of socially supportive actions in the context of a mass shooting. It also calls for establishing a clear-cut distinction between the social strategies (asocial, socially supportive, or socially unsupportive) and the psychological motivations underlying them (individualism, cooperation or genuine altruism) in future research