61 resultados para Weil-Deligne representations


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We investigate dynamics of public perceptions of the 2009 H1N1 influenza pandemic to understand changing patterns of sense-making and blame regarding the outbreak of emerging infectious diseases. We draw on social representation theory combined with a dramaturgical perspective to identify changes in how various collectives are depicted over the course of the pandemic, according to three roles: heroes, villains and victims. Quantitative results based on content analysis of three cross-sectional waves of interviews show a shift from mentions of distant collectives (e.g., far-flung countries) at Wave 1 to local collectives (e.g., risk groups) as the pandemic became of more immediate concern (Wave 2) and declined (Wave 3). Semi-automated content analysis of media coverage shows similar results. Thematic analyses of the discourse associated with collectives revealed that many were consistently perceived as heroes, villains and victims.

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This article reviews research on policy attitudes and ideological values from the perspective of social representations theory. In the first part of the paper, key features of lay political thinking are presented, its pragmatic imperative, its focus on communication and the social functions of shared knowledge. Objectification transforms abstract and group-neutral ideological values into concrete and socially useful knowledge, in particular stereotypes of value-conforming and value-violating groups. Such shared understandings of intergroup relations provide citizens with common reference knowledge which provides the cognitive and cultural basis of policy attitudes. Social representations theory further suggests that lay knowledge reflects the social context in which it has been elaborated (anchoring), an aspect which allows conceptualising aggregate-level differences in policy attitudes. In the second part of the paper, a model of lay conceptions of social order is outlined which organises four shared conceptions of social order, along with the stereotype-based thinking associated with each conception: Moral order, Free Market, Social diversity and Structural inequality. We conclude by arguing that policy attitudes are symbolic devices expressed to justify or to challenge existing social arrangements.

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Evidence from human and non-human primate studies supports a dual-pathway model of audition, with partially segregated cortical networks for sound recognition and sound localisation, referred to as the What and Where processing streams. In normal subjects, these two networks overlap partially on the supra-temporal plane, suggesting that some early-stage auditory areas are involved in processing of either auditory feature alone or of both. Using high-resolution 7-T fMRI we have investigated the influence of positional information on sound object representations by comparing activation patterns to environmental sounds lateralised to the right or left ear. While unilaterally presented sounds induced bilateral activation, small clusters in specific non-primary auditory areas were significantly more activated by contra-laterally presented stimuli. Comparison of these data with histologically identified non-primary auditory areas suggests that the coding of sound objects within early-stage auditory areas lateral and posterior to primary auditory cortex AI is modulated by the position of the sound, while that within anterior areas is not.

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Auditory spatial representations are likely encoded at a population level within human auditory cortices. We investigated learning-induced plasticity of spatial discrimination in healthy subjects using auditory-evoked potentials (AEPs) and electrical neuroimaging analyses. Stimuli were 100 ms white-noise bursts lateralized with varying interaural time differences. In three experiments, plasticity was induced with 40 min of discrimination training. During training, accuracy significantly improved from near-chance levels to approximately 75%. Before and after training, AEPs were recorded to stimuli presented passively with a more medial sound lateralization outnumbering a more lateral one (7:1). In experiment 1, the same lateralizations were used for training and AEP sessions. Significant AEP modulations to the different lateralizations were evident only after training, indicative of a learning-induced mismatch negativity (MMN). More precisely, this MMN at 195-250 ms after stimulus onset followed from differences in the AEP topography to each stimulus position, indicative of changes in the underlying brain network. In experiment 2, mirror-symmetric locations were used for training and AEP sessions; no training-related AEP modulations or MMN were observed. In experiment 3, the discrimination of trained plus equidistant untrained separations was tested psychophysically before and 0, 6, 24, and 48 h after training. Learning-induced plasticity lasted <6 h, did not generalize to untrained lateralizations, and was not the simple result of strengthening the representation of the trained lateralizations. Thus, learning-induced plasticity of auditory spatial discrimination relies on spatial comparisons, rather than a spatial anchor or a general comparator. Furthermore, cortical auditory representations of space are dynamic and subject to rapid reorganization.

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BACKGROUND: Associations between maternal sensitivity and child attachment have been established in many samples, but the strength of the association varies across populations. The sensitivity-attachment link has never been examined at the level of representations nor among premature samples. OBJECTIVE: The present study is aimed at exploring associations between maternal interactive behaviour and children's attachment representations in a population of preterm and full-term infants. METHOD: Maternal interactive behaviour was assessed at 6 and 18 months (Ainsworth Sensitivity Scale & Care Index) and children's attachment representations were measured at 42 months (Attachment Story Completion Task) in a sample of preterm (N=48) and full-term (N=23) infants. RESULTS: Maternal unresponsiveness at 6 months and sensitivity at 18 months explained 54% of the variance of disorganized attachment representations in the full-term group but was not significantly related to attachment patterns in the preterm group. CONCLUSION: These results corroborate previous work on the causes of disorganized attachment and also point to the need to consider the development of attachment differently for children evolving in specific developmental contexts. They especially stress the importance of distinguishing between risk factors associated with the mother as opposed to the child.

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Freud defined the drive as "a concept on the frontier between the mental and the somatic". Today this view that was based on clinical observations interpreted within the psychoanalytical framework, can be revisited in light of the current neuroscientific notions of neuronal plasticity and somatic states. Indeed, through the mechanisms of plasticity experience leaves a trace that forms the neural basis of a representation of the experience. Such a representation R is associated with a somatic state S in the sense taken from the "somatic marker" model of Damasio. Thus, the internal reality of the subject, particularly the unconscious one, is constituted by such connected R's and S's. In the model that we discuss, the posterior insula represents the primary interoceptive cortex where information about somatic states S converges, while in the anterior insula the connection between R and S can take place and establish a neurobiological correlate for the notion of drive. We posit that the re-representations of S associated with R in the anterior insula may correspond to the Vorstellungsrepräsentanz postulated by Freud. We further propose that the tension between R and S established in the anterior insula is discharged according to the notion of drive through the motor arm of the limbic system, namely the anterior cingulate cortex which is heavily connected with the anterior insula.

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Current institutional and official representations of cancer are: coordination, integration, team approaches, quality management, full informed consent, patient centered communication and empowerment. Web access, comprehensive care plan summaries patient centered healthcare interactions and evidence-based programs are different ways of delivering the comprehensive care and follow-up cancer survivors deserve. The question remains, how to best explore and respect, in the meantime, more subjective dimensions such as patient beliefs, values, the meaning of the illness, preferences and needs. These aspects are fundamental elements in the construction of a trusting relationship, so as to find common ground, to be open to discuss anxiety and doubts and to provide information tailored to suit the patient's level of understanding, in order to reduce vulnerability to the feeling of being "lost in transition".

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La venue au monde d'un enfant avec une fente faciale constitue un événement stressant, voire traumatique, pour les parents. Que ce soit à travers le risque de symptômes associés, la logistique d'alimentation ou par simples raisons d'esthétisme, de nombreuses personnes vivent l'annonce de la présence d'une fente faciale comme une intrusion brutale dans le vécu de la grossesse et une interruption momentanée de l'investissement représentationnel du foetus. À travers notre recherche, nous montrons qu'un haut stress n'influe pas forcément négativement sur le développement de la relation entre le parent et l'enfant et que, au contraire, dans le cas des pères, il peut contribuer à l'implication émotionnelle envers le bébé. Le moment de l'annonce de la malformation a aussi une importance dans les représentations à propos de l'enfant puisque si elle est faite durant la période prénatale, elle permet aux parents un réarrangement des représentations afin de mieux accueillir le bébé le jour de sa naissance. The birth of a child with a facial cleft is often seen as a very stressing event for both parents. Risks of comorbidity, difficulty in nutrition or just aesthetical reasons are frequently invoked while describing this moment. The announcement of the deformation is felt like a brutal intrusion in representations associated to pregnancy. Then, we can observe a kind of disinvestment of the coming baby. Through our study, we find that high stress has not always a bad issue on relationship between parents and infants. In contrary, this kind of chronic stress can preserve the well-being of the relationship, especially for fatherhood. The time of facial deformation announcement also plays its part in representations about the baby. Before birth, it opens room for reordering and modifying representations, then the baby will be accepted as it should be on his birthday.

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For the recognition of sounds to benefit perception and action, their neural representations should also encode their current spatial position and their changes in position over time. The dual-stream model of auditory processing postulates separate (albeit interacting) processing streams for sound meaning and for sound location. Using a repetition priming paradigm in conjunction with distributed source modeling of auditory evoked potentials, we determined how individual sound objects are represented within these streams. Changes in perceived location were induced by interaural intensity differences, and sound location was either held constant or shifted across initial and repeated presentations (from one hemispace to the other in the main experiment or between locations within the right hemispace in a follow-up experiment). Location-linked representations were characterized by differences in priming effects between pairs presented to the same vs. different simulated lateralizations. These effects were significant at 20-39 ms post-stimulus onset within a cluster on the posterior part of the left superior and middle temporal gyri; and at 143-162 ms within a cluster on the left inferior and middle frontal gyri. Location-independent representations were characterized by a difference between initial and repeated presentations, independently of whether or not their simulated lateralization was held constant across repetitions. This effect was significant at 42-63 ms within three clusters on the right temporo-frontal region; and at 165-215 ms in a large cluster on the left temporo-parietal convexity. Our results reveal two varieties of representations of sound objects within the ventral/What stream: one location-independent, as initially postulated in the dual-stream model, and the other location-linked.

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Spatial hearing refers to a set of abilities enabling us to determine the location of sound sources, redirect our attention toward relevant acoustic events, and recognize separate sound sources in noisy environments. Determining the location of sound sources plays a key role in the way in which humans perceive and interact with their environment. Deficits in sound localization abilities are observed after lesions to the neural tissues supporting these functions and can result in serious handicaps in everyday life. These deficits can, however, be remediated (at least to a certain degree) by the surprising capacity of reorganization that the human brain possesses following damage and/or learning, namely, the brain plasticity. In this thesis, our aim was to investigate the functional organization of auditory spatial functions and the learning-induced plasticity of these functions. Overall, we describe the results of three studies. The first study entitled "The role of the right parietal cortex in sound localization: A chronometric single pulse transcranial magnetic stimulation study" (At et al., 2011), study A, investigated the role of the right parietal cortex in spatial functions and its chronometry (i.e. the critical time window of its contribution to sound localizations). We concentrated on the behavioral changes produced by the temporarily inactivation of the parietal cortex with transcranial magnetic stimulation (TMS). We found that the integrity of the right parietal cortex is crucial for localizing sounds in the space and determined a critical time window of its involvement, suggesting a right parietal dominance for auditory spatial discrimination in both hemispaces. In "Distributed coding of the auditory space in man: evidence from training-induced plasticity" (At et al., 2013a), study B, we investigated the neurophysiological correlates and changes of the different sub-parties of the right auditory hemispace induced by a multi-day auditory spatial training in healthy subjects with electroencephalography (EEG). We report a distributed coding for sound locations over numerous auditory regions, particular auditory areas code specifically for precise parts of the auditory space, and this specificity for a distinct region is enhanced with training. In the third study "Training-induced changes in auditory spatial mismatch negativity" (At et al., 2013b), study C, we investigated the pre-attentive neurophysiological changes induced with a training over 4 days in healthy subjects with a passive mismatch negativity (MMN) paradigm. We showed that training changed the mechanisms for the relative representation of sound positions and not the specific lateralization themselves and that it changed the coding in right parahippocampal regions. - L'audition spatiale désigne notre capacité à localiser des sources sonores dans l'espace, de diriger notre attention vers les événements acoustiques pertinents et de reconnaître des sources sonores appartenant à des objets distincts dans un environnement bruyant. La localisation des sources sonores joue un rôle important dans la façon dont les humains perçoivent et interagissent avec leur environnement. Des déficits dans la localisation de sons sont souvent observés quand les réseaux neuronaux impliqués dans cette fonction sont endommagés. Ces déficits peuvent handicaper sévèrement les patients dans leur vie de tous les jours. Cependant, ces déficits peuvent (au moins à un certain degré) être réhabilités grâce à la plasticité cérébrale, la capacité du cerveau humain à se réorganiser après des lésions ou un apprentissage. L'objectif de cette thèse était d'étudier l'organisation fonctionnelle de l'audition spatiale et la plasticité induite par l'apprentissage de ces fonctions. Dans la première étude intitulé « The role of the right parietal cortex in sound localization : A chronometric single pulse study » (At et al., 2011), étude A, nous avons examiné le rôle du cortex pariétal droit dans l'audition spatiale et sa chronométrie, c'est-à- dire le moment critique de son intervention dans la localisation de sons. Nous nous sommes concentrés sur les changements comportementaux induits par l'inactivation temporaire du cortex pariétal droit par le biais de la Stimulation Transcrânienne Magnétique (TMS). Nous avons démontré que l'intégrité du cortex pariétal droit est cruciale pour localiser des sons dans l'espace. Nous avons aussi défini le moment critique de l'intervention de cette structure. Dans « Distributed coding of the auditory space : evidence from training-induced plasticity » (At et al., 2013a), étude B, nous avons examiné la plasticité cérébrale induite par un entraînement des capacités de discrimination auditive spatiale de plusieurs jours. Nous avons montré que le codage des positions spatiales est distribué dans de nombreuses régions auditives, que des aires auditives spécifiques codent pour des parties données de l'espace et que cette spécificité pour des régions distinctes est augmentée par l'entraînement. Dans « Training-induced changes in auditory spatial mismatch negativity » (At et al., 2013b), étude C, nous avons examiné les changements neurophysiologiques pré- attentionnels induits par un entraînement de quatre jours. Nous avons montré que l'entraînement modifie la représentation des positions spatiales entraînées et non-entrainées, et que le codage de ces positions est modifié dans des régions parahippocampales.