La reconnaissance des troubles musculo-squelettiques (TMS) comme maladies professionnelles: controverses sociales et trajectoires personnelles

La reconnaissance des troubles musculo-squelettiques (TMS) comme maladies professionnelles : controverses sociales et trajectoires personnelles¦Les TMS sont actuellement considérés comme des problèmes majeurs de santé au travail, mais leur reconnaissance comme maladies professionnelles reste controversée. L'objectif central de cette thèse est de comprendre, dans une perspective de psychologie socio-culturelle intégrant certains apports de la sociologie interactionniste, les conséquences que cette situation peut avoir pour des travailleuses et travailleurs souffrant de ces affections. Au préalable, il s'agira de saisir comment se constituent les controverses sur les TMS et pourquoi ces derniers sont si rarement reconnus comme maladies professionnelles en Suisse. Les principales données sont constituées de documents institutionnels et d'entretiens avec des ouvrières et ouvriers atteints de TMS.¦Les résultats montrent que les enjeux de la reconnaissance des maladies professionnelles ne se limitent pas aux prestations d'assurance et à la prise en charge des coûts engendrés par les maladies. En effet, leur non-reconnaissance contribue à définir les TMS comme des problèmes personnels plutôt que professionnels, ce qui peut entraver les capacités des ouvrières et ouvriers à agir sur leurs conditions de travail. En outre, les explications qui circulent sur les TMS par le biais de discours institutionnels ou informels ont des conséquences sur la manière dont une personne appréhende sa propre maladie. Ces explications de la maladie peuvent être des outils de compréhension, mais aussi contribuer à définir l'identité de la personne malade. Dans ce cas, la reconnaissance du caractère professionnel de la maladie touche aussi à des questions de reconnaissance sociale.¦MSDs are currently considered major occupational health problems, but their recognition as occupational illnesses remains controversial. The central objective of the thesis is to grasp, from a socio-cultural psychology perspective that integrates certain contributions of interactionist sociology, the consequences that these circumstances can have for workers suffering from such ailments. Further, the thesis first aims to understand how controversies about MSDs emerge and why these disorders are so rarely recognized as occupational illnesses in Switzerland. Most of the data used stems from institutional documents and from interviews with workers suffering from MSDs.¦The results show that the stakes of recognizing occupational illnesses are not limited to issues of insurance benefits and the coverage of costs generated by the disorders. In fact, the non-recognition of MSDs contributes to their characterization as personal rather than professional problems, which can in turn impede workers' ability to act to change their working conditions. Furthermore, accounts of and explanations about MSDs circulating by means of institutional or informal discourse have consequences on the way a person may perceive his or her own illness. Such explanations of the illness can be tools for understanding it, but they may also contribute to defining the identity of the affected person. In this case, the recognition of the occupational nature of the illness is also closely related to questions of social recognition.

Modulatory effects of 5Hz rTMS over the primary somatosensory cortex in focal dystonia--an fMRI-TMS study.

Dystonia is associated with impaired somatosensory ability. The electrophysiological method of repetitive transcranial magnetic stimulation (rTMS) can be used for noninvasive stimulation of the human cortex and can alter cortical excitability and associated behavior. Among others, rTMS can alter/improve somatosensory discrimation abilities, as shown in healthy controls. We applied 5Hz-rTMS over the left primary somatosensory cortex (S1) in 5 patients with right-sided writer's dystonia and 5 controls. We studied rTMS effects on tactile discrimination accuracy and concomitant rTMS-induced changes in hemodynamic activity measured by functional magnetic resonance imaging (fMRI). Before rTMS, patients performed worse on the discrimination task than controls even though fMRI showed greater task-related activation bilaterally in the basal ganglia (BG). In controls, rTMS led to improved discrimination; fMRI revealed this was associated with increased activity of the stimulated S1, bilateral premotor cortex and BG. In dystonia patients, rTMS had no effect on discrimination; fMRI showed similar cortical effects to controls except for no effects in BG. Improved discrimination after rTMS in controls is linked to enhanced activation of S1 and BG. Failure of rTMS to increase BG activation in dystonia may be associated with the lack of effect on sensory discrimination in this group and may reflect impaired processing in BG-S1 connections. Alternatively, the increased BG activation seen in the baseline state without rTMS may reflect a compensatory strategy that saturates a BG contribution to this task.

The carbon isotope composition of natural SiC (moissanite) from the Earth's mantle: New discoveries from ophiolites

Moissanite (natural SiC) has been recovered from podiform chromitites of several ophiolite complexes, including the Luobusa and Donqiao ophiolites in Tibet, the Semail ophiolite in Oman and the United Arab Emirates, and the Ray-Iz ophiolite of the Polar Urals, Russia. Taking these new occurrences with the numerous earlier reports of moissanite in diamondiferous kimberlites leads to the conclusion that natural SiC is a widespread mineral in the Earth's mantle, which implies at least locally extremely low redox conditions. The ophiolite moissanite grains are mostly fragments (20 to 150 mu m) with one or more crystal faces, but some euhedral hexagonal grains have also been recovered. Twinned crystals are common in chromitites from the Luobusa ophiolite. The moissanite is rarely colorless, more commonly light bluish-gray to blue or green. Many grains contain inclusions of native Si and Fe-Si alloys (FeSi(2), Fe(3)Si(7)). Secondary ion mass spectrometric (SIMS) analysis shows that the ophiolite-hosted moissanite has a distinctive (13)C-depleted isotopic composition (delta(13)C from -18 to -35 parts per thousand, n=36), much lighter than the main carbon reservoir in the upper mantle (delta(13)C near -5 parts per thousand). The compiled data from moissanite from kimberlites and other mantle settings share the characteristic of strongly (13)C-depleted isotopic composition. This suggests that moissanite originates from a separate carbon reservoir in the mantle or that its formation involved strong isotopic fractionation. The degree of fractionation needed to produce the observed moissanite compositions from the main C-reservoir would be unrealistically large at the high temperatures required for moissanite formation. Subduction of biogenic carbonaceous material could potentially satisfy both the unusual isotopic and redox constraints on moissanite formation, but this material would need to stay chemically isolated from the upper mantle until it reached the high-T stability field of moissanite. The origin of moissanite in the mantle is still unsolved, but all evidence from the upper mantle indicates that it cannot have formed there, barring special and local redox conditions. We suggest, alternatively, that moissanite may have formed in the lower mantle, where the existence of (13)C-depleted carbon is strongly supported by studies of extraterrestrial carbon (Mars, Moon, meteorites). (C) 2009 Elsevier B. V. All rights reserved.

Timing of visual stimuli in V1 and V5/MT: fMRI and TMS

Time perception is used in our day-to-day activities. While we understand quite well how our brain processes vision, touch or taste, brain mechanisms subserving time perception remain largely understudied. In this study, we extended an experiment of previous master thesis run by Tatiana Kenel-Pierre. We focused on time perception in the range of milliseconds. Previous studies have demonstrated the involvement of visual areas V1 and V5/MT in the encoding of temporal information of visual stimuli. Based on these previous findings the aim of the present study was to understand if temporal information was encoded in V1 and extrastriate area V5/MT in different spatial frames i.e., head- centered versus eye-centered. To this purpose we asked eleven healthy volunteers to perform a temporal discrimination task of visual stimuli. Stimuli were presented at 4 different spatial positions (i.e., different combinations of retinotopic and spatiotopic position). While participants were engaged in this task we interfered with the activity of the right dorsal V1 and the right V5/MT with transcranial magnetic stimulation (TMS). Our preliminary results showed that TMS over both V1 and V5/MT impaired temporal discrimination of visual stimuli presented at specific spatial coordinates. But whereas TMS over V1 impaired temporal discrimination of stimuli presented in the lower left quadrant, TMS over V5/MT affected temporal discrimination of stimuli presented at the top left quadrant. Although it is always difficult to draw conclusions from preliminary results, we could tentatively say that our data seem to suggest that both V1 and V5/MT encode visual temporal information in specific spatial frames.