Sound objects in time, space and action

SOUND OBJECTS IN TIME, SPACE AND ACTIONThe term "sound object" describes an auditory experience that is associated with an acoustic event produced by a sound source. At cortical level, sound objects are represented by temporo-spatial activity patterns within distributed neural networks. This investigation concerns temporal, spatial and action aspects as assessed in normal subjects using electrical imaging or measurement of motor activity induced by transcranial magnetic stimulation (TMS).Hearing the same sound again has been shown to facilitate behavioral responses (repetition priming) and to modulate neural activity (repetition suppression). In natural settings the same source is often heard again and again, with variations in spectro-temporal and spatial characteristics. I have investigated how such repeats influence response times in a living vs. non-living categorization task and the associated spatio-temporal patterns of brain activity in humans. Dynamic analysis of distributed source estimations revealed differential sound object representations within the auditory cortex as a function of the temporal history of exposure to these objects. Often heard sounds are coded by a modulation in a bilateral network. Recently heard sounds, independently of the number of previous exposures, are coded by a modulation of a left-sided network.With sound objects which carry spatial information, I have investigated how spatial aspects of the repeats influence neural representations. Dynamics analyses of distributed source estimations revealed an ultra rapid discrimination of sound objects which are characterized by spatial cues. This discrimination involved two temporo-spatially distinct cortical representations, one associated with position-independent and the other with position-linked representations within the auditory ventral/what stream.Action-related sounds were shown to increase the excitability of motoneurons within the primary motor cortex, possibly via an input from the mirror neuron system. The role of motor representations remains unclear. I have investigated repetition priming-induced plasticity of the motor representations of action sounds with the measurement of motor activity induced by TMS pulses applied on the hand motor cortex. TMS delivered to the hand area within the primary motor cortex yielded larger magnetic evoked potentials (MEPs) while the subject was listening to sounds associated with manual than non- manual actions. Repetition suppression was observed at motoneuron level, since during a repeated exposure to the same manual action sound the MEPs were smaller. I discuss these results in terms of specialized neural network involved in sound processing, which is characterized by repetition-induced plasticity.Thus, neural networks which underlie sound object representations are characterized by modulations which keep track of the temporal and spatial history of the sound and, in case of action related sounds, also of the way in which the sound is produced.LES OBJETS SONORES AU TRAVERS DU TEMPS, DE L'ESPACE ET DES ACTIONSLe terme "objet sonore" décrit une expérience auditive associée avec un événement acoustique produit par une source sonore. Au niveau cortical, les objets sonores sont représentés par des patterns d'activités dans des réseaux neuronaux distribués. Ce travail traite les aspects temporels, spatiaux et liés aux actions, évalués à l'aide de l'imagerie électrique ou par des mesures de l'activité motrice induite par stimulation magnétique trans-crânienne (SMT) chez des sujets sains. Entendre le même son de façon répétitive facilite la réponse comportementale (amorçage de répétition) et module l'activité neuronale (suppression liée à la répétition). Dans un cadre naturel, la même source est souvent entendue plusieurs fois, avec des variations spectro-temporelles et de ses caractéristiques spatiales. J'ai étudié la façon dont ces répétitions influencent le temps de réponse lors d'une tâche de catégorisation vivant vs. non-vivant, et les patterns d'activité cérébrale qui lui sont associés. Des analyses dynamiques d'estimations de sources ont révélé des représentations différenciées des objets sonores au niveau du cortex auditif en fonction de l'historique d'exposition à ces objets. Les sons souvent entendus sont codés par des modulations d'un réseau bilatéral. Les sons récemment entendus sont codé par des modulations d'un réseau du côté gauche, indépendamment du nombre d'expositions. Avec des objets sonores véhiculant de l'information spatiale, j'ai étudié la façon dont les aspects spatiaux des sons répétés influencent les représentations neuronales. Des analyses dynamiques d'estimations de sources ont révélé une discrimination ultra rapide des objets sonores caractérisés par des indices spatiaux. Cette discrimination implique deux représentations corticales temporellement et spatialement distinctes, l'une associée à des représentations indépendantes de la position et l'autre à des représentations liées à la position. Ces représentations sont localisées dans la voie auditive ventrale du "quoi".Des sons d'actions augmentent l'excitabilité des motoneurones dans le cortex moteur primaire, possiblement par une afférence du system des neurones miroir. Le rôle des représentations motrices des sons d'actions reste peu clair. J'ai étudié la plasticité des représentations motrices induites par l'amorçage de répétition à l'aide de mesures de potentiels moteurs évoqués (PMEs) induits par des pulsations de SMT sur le cortex moteur de la main. La SMT appliquée sur le cortex moteur primaire de la main produit de plus grands PMEs alors que les sujets écoutent des sons associée à des actions manuelles en comparaison avec des sons d'actions non manuelles. Une suppression liée à la répétition a été observée au niveau des motoneurones, étant donné que lors de l'exposition répétée au son de la même action manuelle les PMEs étaient plus petits. Ces résultats sont discuté en termes de réseaux neuronaux spécialisés impliqués dans le traitement des sons et caractérisés par de la plasticité induite par la répétition. Ainsi, les réseaux neuronaux qui sous-tendent les représentations des objets sonores sont caractérisés par des modulations qui gardent une trace de l'histoire temporelle et spatiale du son ainsi que de la manière dont le son a été produit, en cas de sons d'actions.

Aripiprazole and suicidality.

Cases of psychotic symptoms that worsen after treatment with aripiprazole have been described. We report the case of a 19-year-old patient who, although her psychotic symptoms did not worsen, attempted suicide after switching from risperidone to aripiprazole. The patient had not shown any aggressive behaviour towards herself or others in the 18 months before the introduction of aripiprazole, nor following its discontinuation (12 months). The observed time sequence, with the repetition 4 weeks later of high suicidal behaviour, led us to consider that this effect might possibly be linked to the aripiprazole treatment, which could have increased the risk of suicide in this patient.

Attracting, Developing and Training Effective Teachers - OECD Country Background Report for Ireland

This Country Background Report (CBR) on the teaching career in Ireland forms part of the major OECD study “Attracting, Developing and Retaining Effective Teachers.” Similar reports are being submitted from twenty six other countries. Nine of these countries are also engaged on ‘thematic’ studies of the teaching career, involving site visits by external reviewers appointed by the OECD. The format of the CBRs follows a common pattern, set out by the OECD in its Design and Implementation Plan. This is to facilitate comparative analysis of sub-themes of the reports. Thus, each CBR involves six chapters. The first two – “the national context” and “school system and the teaching force”– are intended to provide succinct overviews of these themes in line with queries posed in the OECD documentation. Each of the other four chapters is designed on a common format – identification of policy concerns; data, trends and factors; policy initiatives and their impact. Specific questions are posed regarding data, trends and factors. The same questions may be posed in relation to more than one sub-theme which gives rise to some repetition in the report, but is important for the comparative analysis.

Antecedents, psychiatric characteristics and follow-up of adolescents hospitalized for suicide attempt of overwhelming suicidal ideation.

To evaluate the socio-demographic as well as the health and psychiatric profiles of adolescents hospitalised for suicide attempt or overwhelming suicide ideation and to assess repetition of suicide attempt over a period of 18 months. Between April 2000 and September 2001, all patients aged 16 to 21 years admitted to the University Hospitals of Geneva and Lausanne for suicide attempt or ideation were included in the study. At this time (T0) semi-structured face to face interviews were conducted to identify socio-demographic data, mental health and antecedents regarding suicidal conducts. Current psychiatric status was assessed with the MINI (Mini International Neuropsychiatric Instrument). At T1 and T2, reassessments included psychiatric status (MINI) as well as lifestyles, socio-professional situation and suicidal behaviours. At T0, 269 subjects met the study criteria, among whom 83 subjects (56 girls and 27 boys) left the hospital too quickly to be involved or refused to participate in the study (final sample at T0: 149 girls; 37 boys). The participation rate at T1 and T2 was respectively 66% and 62% of the original sample. The percentage of adolescents meeting the criteria for psychiatric diagnoses (91%) was high: affective disorder (78%); anxiety disorder (64%); substance use disorder (39%); eating disorder (9%); psychotic disorder (11%); antisocial personality (7%) with most subjects (85%) having more than one disorder. Around 90% of the subjects interviewed at T1, and/or T2, had received follow-up care after their hospitalisation, either by a primary care physician or a psychotherapist or both. Two subjects died of violent death and 18% made a further suicide attempt. Most adolescents hospitalised for suicidal episodes suffer from psychiatric problems which should be addressed by a careful psychiatric assessment, followed up if needed by a structured after care plan.

Substance use and suicidal conducts : a study of adolescents hospitalized for suicide attempt and ideation

RESUME Objectifs: Etudier la prévalence des troubles liés à l'utilisation de substances psychoatives parmi des adolescents suicidaires; évaluer l'influence de la prise de substances psychoactives sur le geste suicidaire; analyser l'association entre les troubles liés à l'utilisation de substances psychoactives et le risque de récidive de la conduite suicidaire. Méthode: 186 adolescents, âgés de 16 à 21 ans, hospitalisés pour tentative de suicide ou idées suicidaires envahissantes, ont été inclus. Parmi eux, 148 ont été revus pour évaluation à 6 et/ou 18 mois. Des diagnostics psychiatriques, basés sur les critères du DSM-IV, ont été posés à l'aide d'un questionnaire, le MINI (Mini International Neuropsychiatric Interview). Résultats: A l'inclusion, 39.2% des sujets avaient un trouble lié à l'utilisation de substances psychoactives. Parmi eux, une proportion significativement plus élevée était sous l'influence d'alcool ou drogue au moment de la tentative de suicide (44.3% versus 25.4%). Des 148 adolescents suivis et revus à 6 ou 18 mois, 2 sont décédés par suicide et il y a eu 30 récidives de tentative de suicide durant l'étude. Une association significative a été trouvée entre les récidives de suicide et un diagnostic d'abus/dépendance à l'alcool à l'inclusion (OR=3.3; CI 0.7-15.0; 0R=2.6, CI 0.7-9.3). Des antécédents de plusieurs tentatives de suicide (OR=3.2; CI 1.1-10.0) et un âge supérieur à 19 ans (OR=3.2; CI 1.1-9.2) à l'inclusion étaient associés à la probabilité de mort par suicide ou de récidive de tentative de suicide. Conclusion: Parmi les adolescents hospitalisés pour tentative de suicide ou idées suicidaires envahissantes, le risque de décès ou de récidive est important. Ce risque est associé, entre autres, à des antécédents suicidaires et au diagnostic de trouble lié à l'utilisation de substances psychoactives. Le risque suicidaire ainsi que la consommation de substances psychoactives devrait être évalué chez les adolescents. De plus, les sujets jugés à risque devraient être suivis systématiquement après une hospitalisation pour conduite suicidaire. ABSTRACT Aim: To study the prevalence of psychoactive substance use disorder (PSUD) among suicidal adolescents, psychoactive substance intoxication at the moment of the attempt and the association between PSUD at baseline and either occurrence of suicide or repetition of suicide attempt(s). Methods: 186 adolescents aged 16 to 21 hospitalised for suicide attempt or overwhelming suicidal ideation were included (TO); 148 of them were traced again for evaluations after 6 months and/or 18 months. DSM-IV diagnoses were assessed each time using the Mini International Neuropsychiatric Interview. Results: At TO, 39.2% of the subjects were found to have a PSUD. Among them, a significantly higher proportion was intoxicated at the time of the attempt than those without PSUD (44-.3% vs. 25.4%). Among the 148 adolescents who could be traced at either Ti or T2, two died from suicide and 30 repeated suicide attempt once or more time. A marginally significant association was found between death by suicide/repetition of suicide attempt and alcohol abuse/dependence at baseline (0R=3.3; CI 0.7-15.0; 0R=2.6, CI 0.7-9.3). More than one suicide attempt before admission to hospital at TO (OR=3.2; CI 1.1-10.0) and age over 19 at TO (0R=3.2; CI 1.1-9.2) were independently associated with the likelihood of death by suicide or repetition of suicide attempt. Conclusion: Among adolescents hospitalised for suicide attempt or overwhelming suicidal ideation, the risk of death or repetition of attempt is high and is associated with previous suicide attempts - especially among older adolescents - and also marginally associated with PSUD; these adolescents should be carefully evaluated for such risks and followed up once discharged from the hospital.

Repeating with the right hemisphere: reduced interactions between phonological and lexical-semantic systems in crossed aphasia?

Knowledge on the patterns of repetition amongst individuals who develop language deficits in association with right hemisphere lesions (crossed aphasia) is very limited. Available data indicate that repetition in some crossed aphasics experiencing phonological processing deficits is not heavily influenced by lexical-semantic variables (lexicality, imageability, and frequency) as is regularly reported in phonologically-impaired cases with left hemisphere damage. Moreover, in view of the fact that crossed aphasia is rare, information on the role of right cortical areas and white matter tracts underpinning language repetition deficits is scarce. In this study, repetition performance was assessed in two patients with crossed conduction aphasia and striatal/capsular vascular lesions encompassing the right arcuate fasciculus (AF) and inferior frontal-occipital fasciculus (IFOF), the temporal stem and the white matter underneath the supramarginal gyrus. Both patients showed lexicality effects repeating better words than non-words, but manipulation of other lexical-semantic variables exerted less influence on repetition performance. Imageability and frequency effects, production of meaning-based paraphrases during sentence repetition, or better performance on repeating novel sentences than overlearned clichés were hardly ever observed in these two patients. In one patient, diffusion tensor imaging disclosed damage to the right long direct segment of the AF and IFOF with relative sparing of the anterior indirect and posterior segments of the AF, together with fully developed left perisylvian white matter pathways. These findings suggest that striatal/capsular lesions extending into the right AF and IFOF in some individuals with right hemisphere language dominance are associated with atypical repetition patterns which might reflect reduced interactions between phonological and lexical-semantic processes.

Feasibility and clinical outcomes when using practice guidelines for evaluation of fever in returning travelers and migrants : a validation study.

BACKGROUND: Practice guidelines for examining febrile patients presenting upon returning from the tropics were developed to assist primary care physicians in decision making. Because of the low level of evidence available in this field, there was a need to validate them and assess their feasibility in the context they have been designed for. OBJECTIVES: The objectives of the study were to (1) evaluate physicians' adherence to recommendations; (2) investigate reasons for non-adherence; and (3) ensure good clinical outcome of patients, the ultimate goal being to improve the quality of the guidelines, in particular to tailor them for the needs of the target audience and population. METHODS: Physicians consulting the guidelines on the Internet (www.fevertravel.ch) were invited to participate in the study. Navigation through the decision chart was automatically recorded, including diagnostic tests performed, initial and final diagnoses, and clinical outcomes. The reasons for non-adherence were investigated and qualitative feedback was collected. RESULTS: A total of 539 physician/patient pairs were included in this study. Full adherence to guidelines was observed in 29% of the cases. Figure-specific adherence rate was 54.8%. The main reasons for non-adherence were as follows: no repetition of malaria tests (111/352) and no presumptive antibiotic treatment for febrile diarrhea (64/153) or abdominal pain without leukocytosis (46/101). Overall, 20% of diversions from guidelines were considered reasonable because there was an alternative presumptive diagnosis or the symptoms were mild, which means that the corrected adherence rate per case was 40.6% and corrected adherence per figure was 61.7%. No death was recorded and all complications could be attributed to the underlying illness rather than to adherence to guidelines. CONCLUSIONS: These guidelines proved to be feasible, useful, and leading to good clinical outcomes. Almost one third of physicians strictly adhered to the guidelines. Other physicians used the guidelines not to forget specific diagnoses but finally diverged from the proposed attitudes. These diversions should be scrutinized for further refinement of the guidelines to better fit to physician and patient needs.

Evolutionary games on complex networks : the emergence and maintenance of cooperation

Abstract The object of game theory lies in the analysis of situations where different social actors have conflicting requirements and where their individual decisions will all influence the global outcome. In this framework, several games have been invented to capture the essence of various dilemmas encountered in many common important socio-economic situations. Even though these games often succeed in helping us understand human or animal behavior in interactive settings, some experiments have shown that people tend to cooperate with each other in situations for which classical game theory strongly recommends them to do the exact opposite. Several mechanisms have been invoked to try to explain the emergence of this unexpected cooperative attitude. Among them, repeated interaction, reputation, and belonging to a recognizable group have often been mentioned. However, the work of Nowak and May (1992) showed that the simple fact of arranging the players according to a spatial structure and only allowing them to interact with their immediate neighbors is sufficient to sustain a certain amount of cooperation even when the game is played anonymously and without repetition. Nowak and May's study and much of the following work was based on regular structures such as two-dimensional grids. Axelrod et al. (2002) showed that by randomizing the choice of neighbors, i.e. by actually giving up a strictly local geographical structure, cooperation can still emerge, provided that the interaction patterns remain stable in time. This is a first step towards a social network structure. However, following pioneering work by sociologists in the sixties such as that of Milgram (1967), in the last few years it has become apparent that many social and biological interaction networks, and even some technological networks, have particular, and partly unexpected, properties that set them apart from regular or random graphs. Among other things, they usually display broad degree distributions, and show small-world topological structure. Roughly speaking, a small-world graph is a network where any individual is relatively close, in terms of social ties, to any other individual, a property also found in random graphs but not in regular lattices. However, in contrast with random graphs, small-world networks also have a certain amount of local structure, as measured, for instance, by a quantity called the clustering coefficient. In the same vein, many real conflicting situations in economy and sociology are not well described neither by a fixed geographical position of the individuals in a regular lattice, nor by a random graph. Furthermore, it is a known fact that network structure can highly influence dynamical phenomena such as the way diseases spread across a population and ideas or information get transmitted. Therefore, in the last decade, research attention has naturally shifted from random and regular graphs towards better models of social interaction structures. The primary goal of this work is to discover whether or not the underlying graph structure of real social networks could give explanations as to why one finds higher levels of cooperation in populations of human beings or animals than what is prescribed by classical game theory. To meet this objective, I start by thoroughly studying a real scientific coauthorship network and showing how it differs from biological or technological networks using divers statistical measurements. Furthermore, I extract and describe its community structure taking into account the intensity of a collaboration. Finally, I investigate the temporal evolution of the network, from its inception to its state at the time of the study in 2006, suggesting also an effective view of it as opposed to a historical one. Thereafter, I combine evolutionary game theory with several network models along with the studied coauthorship network in order to highlight which specific network properties foster cooperation and shed some light on the various mechanisms responsible for the maintenance of this same cooperation. I point out the fact that, to resist defection, cooperators take advantage, whenever possible, of the degree-heterogeneity of social networks and their underlying community structure. Finally, I show that cooperation level and stability depend not only on the game played, but also on the evolutionary dynamic rules used and the individual payoff calculations. Synopsis Le but de la théorie des jeux réside dans l'analyse de situations dans lesquelles différents acteurs sociaux, avec des objectifs souvent conflictuels, doivent individuellement prendre des décisions qui influenceront toutes le résultat global. Dans ce cadre, plusieurs jeux ont été inventés afin de saisir l'essence de divers dilemmes rencontrés dans d'importantes situations socio-économiques. Bien que ces jeux nous permettent souvent de comprendre le comportement d'êtres humains ou d'animaux en interactions, des expériences ont montré que les individus ont parfois tendance à coopérer dans des situations pour lesquelles la théorie classique des jeux prescrit de faire le contraire. Plusieurs mécanismes ont été invoqués pour tenter d'expliquer l'émergence de ce comportement coopératif inattendu. Parmi ceux-ci, la répétition des interactions, la réputation ou encore l'appartenance à des groupes reconnaissables ont souvent été mentionnés. Toutefois, les travaux de Nowak et May (1992) ont montré que le simple fait de disposer les joueurs selon une structure spatiale en leur permettant d'interagir uniquement avec leurs voisins directs est suffisant pour maintenir un certain niveau de coopération même si le jeu est joué de manière anonyme et sans répétitions. L'étude de Nowak et May, ainsi qu'un nombre substantiel de travaux qui ont suivi, étaient basés sur des structures régulières telles que des grilles à deux dimensions. Axelrod et al. (2002) ont montré qu'en randomisant le choix des voisins, i.e. en abandonnant une localisation géographique stricte, la coopération peut malgré tout émerger, pour autant que les schémas d'interactions restent stables au cours du temps. Ceci est un premier pas en direction d'une structure de réseau social. Toutefois, suite aux travaux précurseurs de sociologues des années soixante, tels que ceux de Milgram (1967), il est devenu clair ces dernières années qu'une grande partie des réseaux d'interactions sociaux et biologiques, et même quelques réseaux technologiques, possèdent des propriétés particulières, et partiellement inattendues, qui les distinguent de graphes réguliers ou aléatoires. Entre autres, ils affichent en général une distribution du degré relativement large ainsi qu'une structure de "petit-monde". Grossièrement parlant, un graphe "petit-monde" est un réseau où tout individu se trouve relativement près de tout autre individu en termes de distance sociale, une propriété également présente dans les graphes aléatoires mais absente des grilles régulières. Par contre, les réseaux "petit-monde" ont, contrairement aux graphes aléatoires, une certaine structure de localité, mesurée par exemple par une quantité appelée le "coefficient de clustering". Dans le même esprit, plusieurs situations réelles de conflit en économie et sociologie ne sont pas bien décrites ni par des positions géographiquement fixes des individus en grilles régulières, ni par des graphes aléatoires. De plus, il est bien connu que la structure même d'un réseau peut passablement influencer des phénomènes dynamiques tels que la manière qu'a une maladie de se répandre à travers une population, ou encore la façon dont des idées ou une information s'y propagent. Ainsi, durant cette dernière décennie, l'attention de la recherche s'est tout naturellement déplacée des graphes aléatoires et réguliers vers de meilleurs modèles de structure d'interactions sociales. L'objectif principal de ce travail est de découvrir si la structure sous-jacente de graphe de vrais réseaux sociaux peut fournir des explications quant aux raisons pour lesquelles on trouve, chez certains groupes d'êtres humains ou d'animaux, des niveaux de coopération supérieurs à ce qui est prescrit par la théorie classique des jeux. Dans l'optique d'atteindre ce but, je commence par étudier un véritable réseau de collaborations scientifiques et, en utilisant diverses mesures statistiques, je mets en évidence la manière dont il diffère de réseaux biologiques ou technologiques. De plus, j'extrais et je décris sa structure de communautés en tenant compte de l'intensité d'une collaboration. Finalement, j'examine l'évolution temporelle du réseau depuis son origine jusqu'à son état en 2006, date à laquelle l'étude a été effectuée, en suggérant également une vue effective du réseau par opposition à une vue historique. Par la suite, je combine la théorie évolutionnaire des jeux avec des réseaux comprenant plusieurs modèles et le réseau de collaboration susmentionné, afin de déterminer les propriétés structurelles utiles à la promotion de la coopération et les mécanismes responsables du maintien de celle-ci. Je mets en évidence le fait que, pour ne pas succomber à la défection, les coopérateurs exploitent dans la mesure du possible l'hétérogénéité des réseaux sociaux en termes de degré ainsi que la structure de communautés sous-jacente de ces mêmes réseaux. Finalement, je montre que le niveau de coopération et sa stabilité dépendent non seulement du jeu joué, mais aussi des règles de la dynamique évolutionnaire utilisées et du calcul du bénéfice d'un individu.

Silencing mutant ataxin-3 rescues motor deficits and neuropathology in machado-joseph disease transgenic mice.

Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3 (SCA3) is an autosomal dominantly-inherited neurodegenerative disorder caused by the over-repetition of a CAG codon in the MJD1 gene. This expansion translates into a polyglutamine tract that confers a toxic gain-of-function to the mutant protein - ataxin-3, leading to neurodegeneration in specific brain regions, with particular severity in the cerebellum. No treatment able to modify the disease progression is available. However, gene silencing by RNA interference has shown promising results. Therefore, in this study we investigated whether lentiviral-mediated allele-specific silencing of the mutant ataxin-3 gene, after disease onset, would rescue the motor behavior deficits and neuropathological features in a severely impaired transgenic mouse model of MJD. For this purpose, we injected lentiviral vectors encoding allele-specific silencing-sequences (shAtx3) into the cerebellum of diseased transgenic mice expressing the targeted C-variant of mutant ataxin-3 present in 70% of MJD patients. This variation permits to discriminate between the wild-type and mutant forms, maintaining the normal function of the wild-type allele and silencing only the mutant form. Quantitative analysis of rotarod performance, footprint and activity patterns revealed significant and robust alleviation of gait, balance (average 3-fold increase of rotarod test time), locomotor and exploratory activity impairments in shAtx3-injected mice, as compared to control ones injected with shGFP. An important improvement of neuropathology was also observed, regarding the number of intranuclear inclusions, calbindin and DARPP-32 immunoreactivity, fluorojade B and Golgi staining and molecular and granular layers thickness. These data demonstrate for the first time the efficacy of gene silencing in blocking the MJD-associated motor-behavior and neuropathological abnormalities after the onset of the disease, supporting the use of this strategy for therapy of MJD.

Racial Stereotypes in Fictions of Slavery: Uncle Tom´s Cabin by Harriet Beecher Stowe and O Escravo by José Evaristo D’ Almeida

Most stereotypes about Africans and their descendants started with colonialism in the fifteenth century. The encounter between Africans and Europeans facilitated the creation of myths and stereotypes about the colonized peoples, which were made effective through the naturalization of differences. The relationship between skin color and slavery developed to produce a racialized system of forced labor on which colonialism depended for its survival. Stereotypes functioned to legitimize colonial authority by building the notion that the colonizer ruled over the colonized because of an innate superiority. Therefore, stereotyping is an effective "discursive strategy" (Bhabha) based on fixity and repetition with the aim of controlling the other. Harriet Beecher Stowe’s Uncle Tom’s Cabin and José Evaristo D’Almeida O Escravo both denounced the evils of slavery in the United States of America and Cape Verde respectively, claiming for the end of the institution. However, they are both ambivalent towards slaves and blacks, being unable to envisage social equality for the two races. Both authors construct their black characters as stereotypical others, but they depict the light-skin characters as superior both culturally and physically. The bi-racial characters are portrayed as the ones who possess beauty and intelligence as an inheritance from their European ancestry, while blacks are relegated to the margins. We need to consider, however, that slavery in Cape Verde had different characteristics from its counterpart in the United States of America. In Cape Verde the Africans outnumbered the Europeans and that circumstance favored miscegenation and the emergence of forms of mixed culture, which came to be seen as positive and natural. In the United States of America miscegenation was regarded as a taboo since early. And even after Emancipation, “the one-drop rule” made the offspring of an African descendant black, however 'white' he or she might be.

Voluntary Explicit versus Involuntary Conceptual Memory Are Associated with Dissociable fMRI Responses in Hippocampus, Amygdala, and Parietal Cortex for Emotional and Neutral Word Pairs.

Although functional neuroimaging studies have supported the distinction between explicit and implicit forms of memory, few have matched explicit and implicit tests closely, and most of these tested perceptual rather than conceptual implicit memory. We compared event-related fMRI responses during an intentional test, in which a group of participants used a cue word to recall its associate from a prior study phase, with those in an incidental test, in which a different group of participants used the same cue to produce the first associate that came to mind. Both semantic relative to phonemic processing at study, and emotional relative to neutral word pairs, increased target completions in the intentional test, but not in the incidental test, suggesting that behavioral performance in the incidental test was not contaminated by voluntary explicit retrieval. We isolated the neural correlates of successful retrieval by contrasting fMRI responses to studied versus unstudied cues for which the equivalent "target" associate was produced. By comparing the difference in this repetition-related contrast across the intentional and incidental tests, we could identify the correlates of voluntary explicit retrieval. This contrast revealed increased bilateral hippocampal responses in the intentional test, but decreased hippocampal responses in the incidental test. A similar pattern in the bilateral amygdale was further modulated by the emotionality of the word pairs, although surprisingly only in the incidental test. Parietal regions, however, showed increased repetition-related responses in both tests. These results suggest that the neural correlates of successful voluntary explicit memory differ in directionality, even if not in location, from the neural correlates of successful involuntary implicit (or explicit) memory, even when the incidental test taps conceptual processes.

A comparison of in vivo 13C MR brain glycogen quantification at 9.4 and 14.1 T.

The high molecular weight and low concentration of brain glycogen render its noninvasive quantification challenging. Therefore, the precision increase of the quantification by localized (13) C MR at 9.4 to 14.1 T was investigated. Signal-to-noise ratio increased by 66%, slightly offset by a T(1) increase of 332 ± 15 to 521 ± 34 ms. Isotopic enrichment after long-term (13) C administration was comparable (≈ 40%) as was the nominal linewidth of glycogen C1 (≈ 50 Hz). Among the factors that contributed to the 66% observed increase in signal-to-noise ratio, the T(1) relaxation time impacted the effective signal-to-noise ratio by only 10% at a repetition time = 1 s. The signal-to-noise ratio increase together with the larger spectral dispersion at 14.1 T resulted in a better defined baseline, which allowed for more accurate fitting. Quantified glycogen concentrations were 5.8 ± 0.9 mM at 9.4 T and 6.0 ± 0.4 mM at 14.1 T; the decreased standard deviation demonstrates the compounded effect of increased magnetization and improved baseline on the precision of glycogen quantification.

Calpastatin-mediated inhibition of calpains in the mouse brain prevents mutant ataxin 3 proteolysis, nuclear localization and aggregation, relieving Machado-Joseph disease.

Machado-Joseph disease is the most frequently found dominantly-inherited cerebellar ataxia. Over-repetition of a CAG trinucleotide in the MJD1 gene translates into a polyglutamine tract within the ataxin 3 protein, which upon proteolysis may trigger Machado-Joseph disease. We investigated the role of calpains in the generation of toxic ataxin 3 fragments and pathogenesis of Machado-Joseph disease. For this purpose, we inhibited calpain activity in mouse models of Machado-Joseph disease by overexpressing the endogenous calpain-inhibitor calpastatin. Calpain blockage reduced the size and number of mutant ataxin 3 inclusions, neuronal dysfunction and neurodegeneration. By reducing fragmentation of ataxin 3, calpastatin overexpression modified the subcellular localization of mutant ataxin 3 restraining the protein in the cytoplasm, reducing aggregation and nuclear toxicity and overcoming calpastatin depletion observed upon mutant ataxin 3 expression. Our findings are the first in vivo proof that mutant ataxin 3 proteolysis by calpains mediates its translocation to the nucleus, aggregation and toxicity and that inhibition of calpains may provide an effective therapy for Machado-Joseph disease.

Oligomerization and DNA binding of Ler, a master regulator of pathogenicity of enterohemorrhagic and enteropathogenic Escherichia coli

Ler is a DNA-binding, oligomerizable protein that regulates pathogenicity islands in enterohemorrhagic and enteropathogenic Escherichia coli strains. Ler counteracts the transcriptional silencing effect of H-NS, another oligomerizable nucleoid-associated protein. We studied the oligomerization of Ler in the absence and presence of DNA by atomic force microscopy. Ler forms compact particles with a multimodal size distribution corresponding to multiples of 35 units of Ler. DNA wraps around Ler particles that contain more than 1516 Ler monomers. The resulting shortening of the DNA contour length is in agreement with previous measurements of the length of DNA protected by Ler in footprinting assays. We propose that the repetition unit corresponds to the number of monomers per turn of a tight helical Ler oligomer. While the repressor (H-NS) and anti-repressor (Ler) have similar DNA-binding domains, their oligomerization domains are unrelated. We suggest that the different oligomerization behavior of the two proteins explains the opposite results of their interaction with the same or proximal regions of DNA.

Antecedents, psychiatric characteristics and follow-up of adolescents hospitalized for suicide attempt of overwhelming suicidal ideation.

OBJECTIVES: To evaluate the socio-demographic as well as the health and psychiatric profiles of adolescents hospitalised for suicide attempt or overwhelming suicide ideation and to assess repetition of suicide attempt over a period of 18 months. PATIENTS AND METHODS: Between April 2000 and September 2001, all patients aged 16 to 21 years admitted to the University Hospitals of Geneva and Lausanne for suicide attempt or ideation were included in the study. At this time (T0) semi-structured face to face interviews were conducted to identify socio-demographic data, mental health and antecedents regarding suicidal conducts. Current psychiatric status was assessed with the MINI (Mini International Neuropsychiatric Instrument). At T1 and T2, reassessments included psychiatric status (MINI) as well as lifestyles, socio-professional situation and suicidal behaviours. RESULTS: At T0, 269 subjects met the study criteria, among whom 83 subjects (56 girls and 27 boys) left the hospital too quickly to be involved or refused to participate in the study (final sample at T0: 149 girls; 37 boys). The participation rate at T1 and T2 was respectively 66% and 62% of the original sample. The percentage of adolescents meeting the criteria for psychiatric diagnoses (91%) was high: affective disorder (78%); anxiety disorder (64%); substance use disorder (39%); eating disorder (9%); psychotic disorder (11%); antisocial personality (7%) with most subjects (85%) having more than one disorder. Around 90% of the subjects interviewed at T1, and/or T2, had received follow-up care after their hospitalisation, either by a primary care physician or a psychotherapist or both. Two subjects died of violent death and 18% made a further suicide attempt. CONCLUSION: Most adolescents hospitalised for suicidal episodes suffer from psychiatric problems which should be addressed by a careful psychiatric assessment, followed up if needed by a structured after care plan.