Direct mapping rather than motor prediction subserves modulation of corticospinal excitability during observation of actions in real time

Motor facilitation refersto the specific increment in corticospinal excitability (CSE)elicited by the observation of actions performed by others. To date,the precise nature of the mechanism at the basis of this phenomenonis unknown. One possibility is that motor facilitation is driven by apredictive process reminiscent of the role of forward models in motorcontrol. Alternatively, motor facilitation may result from a model-freemechanism by which the basic elements of the observed action aredirectly mapped onto their cortical representations. Our study wasdesigned to discern these alternatives. To this aim, we recorded thetime course of CSE for the first dorsal interosseous (FDI) and theabductor digiti minimi (ADM) during observation of three graspingactions in real time, two of which strongly diverged in kinematicsfrom their natural (invariant) form. Although artificially slow movementsused in most action observation studies might enhance theobserver?s discrimination performance, the use of videos in real timeis crucial to maintain the time course of CSE within the physiologicalrange of daily actions. CSE was measured at 4 time points within a240-ms window that best captured the kinematic divergence from theinvariant form. Our results show that CSE of the FDI, not the ADM,closely follows the functional role of the muscle despite the mismatchbetween the natural and the divergent kinematics. We propose thatmotor facilitation during observation of actions performed in real timereflects the model-free coding of perceived movement following adirect mapping mechanism.Fil: Gueugneau, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Mc Cabe, Sofia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Villalta, Jorge Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Grafton, Scott T.. University of California. Department of Psychology; Estados UnidosFil: Della Maggiore, Valeria Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentin

An empirical model for continuous and weighted metric aggregation

International audienceIt is now understood that software metrics alone are not enough to characterize software quality. To cope with this problem, most of advanced and/or industrially validated quality models aggregate software metrics: for example, cy- clomatic complexity is combined with test coverage to stress the fact that it is more important to cover complex methods than accessors. Yet, aggregating and weighting metrics to produce quality indexes is a difficult task. Indeed certain weighting approaches may lead to abnormal situations where a developer increasing the quality of a software component sees the overall quality degrade. Finally, mapping combinations of metric values to quality indexes may be a problem when using thresholds. In this paper, we present the problems we faced when designing the Squale quality model, then we present an empirical solution based on weighted aggregations and on continuous functions. The solution has been termed the Squale quality model and validated over 4 years with two large multinational companies: Air France-KLM and PSA Peugeot- Citroen

A Dominance Analysis Approach Applied to Psychological Factors Associated with Binge Drinking among University Students

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Pharmaceutical cognitive doping in students: a chimeric way to get-a-head?

International audienceFor students, the pressing demands for memorization, top-level performance, and peer competition create an environment favorable for pharmaceutical cognitive doping behavior. We aimed to describe recent practices and the benefit/risk ratio of such behavior and to discuss the issues at stake. The prevalence of pharmaceutical cognitive doping among students has been reported from 1.3% to 33% across studies, with variations depending on country and definition of pharmaceutical cognitive doping. The therapeutic classes most frequently cited as being diverted for doping purposes are psychostimulants and nootropics (methylphenidate, modafinil, piracetam), corticosteroids, sedative drugs and beta-blockers. Some illegal substances such as cannabis, amphetamines and cocaine are also consumed in order to boost mental function. Finally, over-the-counter products, such as caffeine-based tablets or energy drinks, or alcohol, are also widely used by students whose motivations involve enhanced performance, concentration, memory, and staying awake during the revision and exam period. However, the expected (often fantasized) effectiveness of these products does not correspond to the reality of a modest controversial impact on cognitive performance. There appears to be an emerging profile of the student more inclined to doping behavior. Cognitive doping thus raises the question of its regulation, opening a debate opposing, on one hand, individual freedom and supposed collective benefits and, on the other hand, health consequences, educational (in)equality, and the risk of tarnished academic success. Strengthening school and university medicine, through prevention campaigns and the identification of subjects at risk, is essential to limit the extent, risk, and damages associated with such practices

Cerebellar hypermetabolism in alcohol use disorder: compensatory mechanism or maladaptive plasticity?

International audienceBACKGROUND: Despite severe structural brain abnormalities within the fronto-cerebellar circuit (FCC), cerebellar metabolism studied with FDG-PET is relatively preserved in patients with alcohol use disorder (AUD). The compensatory role of the cerebellum has been explored mainly through fMRIexamination of AUD patients with preserved level of performance. The present study aims at examining cerebellar metabolism and its relationship with regional brain metabolism and neuropsychological functioning in AUD patients.METHODS: Thirty-two recently detoxified AUD patients and 23 controls underwent an FDG-PET examination at rest. Participants also performed a neuropsychological battery assessing executive functions, verbal memory and ataxia.RESULTS: Compared to controls, AUD patients had higher glucose-uptake in the cerebellar lobules VIII, in association with hypometabolism notably in several nodes of the FCC. Cerebellar hypermetabolism correlated negatively with regional hypometabolism in the premotor and frontal cortices. This pattern of regional hypermetabolism and hypometabolism related to ataxia and working memory deficits.CONCLUSIONS: These specific brain-behaviour relationships do not fulfil the criteria for brain compensatory processes. Cerebellar hypermetabolism may rather reflect the involvement of different pathological mechanisms, leading to a maladaptive plasticity phenomenon within the FCC in AUD patients who are early in abstinence. Further studies are required to examine the contributions of structural and functional connectivity alterations in the cerebellar hypermetabolism and the changes of these pathological mechanisms with abstinence or relapse

Dissociating thalamic alterations in Alcohol Use Disorder defines specificity of Korsakoff syndrome

International audienceThe thalamus, a relay organ consisting of several nuclei, is shared between the frontocerebellar circuit and the Papez circuit, both particularly affected in alcohol use disorder. Shrinkage of the thalamus is known to be more severe in alcoholics with Korsakoff's syndrome than in those without neurological complications (uncomplicated alcoholics). While thalamic atrophy could thus be a key factor explaining amnesia in Korsakoff's syndrome, the loci and nature of alterations within the thalamic nuclei in uncomplicated alcoholics and alcoholics with Korsakoff's syndrome remains unclear. Indeed, the literature from animal and human models is disparate regarding whether the anterior thalamic nuclei, or the mediodorsal nuclei are particularly affected and would be responsible for amnesia. Sixty-two participants (20 healthy controls, 26 uncomplicated alcoholics and 16 patients with Korsakoff's syndrome) underwent a diffusion tensor imaging sequence and T1-weighted MRI. State-of-the-art probabilistic tractography was used to segment the thalamus according to its connections to the prefrontal cortex and cerebellar Cruses I and II for the frontocerebellar circuit's executive loop, the precentral gyrus and cerebellar lobes IV-VI for the frontocerebellar circuit's motor loop, and hippocampus for the Papez circuit. The connectivity and volumes of these parcellations were calculated. Tractography showed that the hippocampus was principally connected to the anterior thalamic nuclei while the prefrontal cortex was principally connected to the mediodorsal nuclei. The fibre pathways connecting these brain regions and their respective thalamic nuclei have also been validated. ANCOVA, with age and gender as covariates, on connectivity measures showed abnormalities in both patient groups for thalamic parcellations connected to the hippocampus only [F(2,57) = 12.1; P patients with Korsakoff's syndrome (P = 0.0036). Two different mechanisms seem to affect the thalamus. In the frontocerebellar circuit, atrophy of the mediodorsal nuclei may lead to the alterations, whereas in the Papez circuit, disconnection between the anterior nuclei and hippocampus may be the leading factor. Shrinkage of the anterior nuclei could be specific to patients with Korsakoff's syndrome, hence a potential neuroimaging marker of its pathophysiology, or more generally of thalamic amnesia for which Korsakoff's syndrome has historically been used as a model

Alcool et drogues à l’université de Caen Normandie (ADUC) : une contribution utile pour l’addictovigilance sur la population estudiantine

International audienceIntroductionAlcool et drogues à l’université de Caen Normandie (ADUC) est une enquête longitudinale multidisciplinaire portant sur les étudiants de l’université de Caen Normandie (UCN). Elle vise à générer une connaissance actualisée des consommations de médicaments/drogue en population estudiantine et de suivre l’évolution de ces consommations au cours des années.MéthodesUne enquête sur le mésusage de substances psychoactives et de médicaments a été envoyée à tous les étudiants de l’UCN en novembre 2016.RésultatsQuatre mille soixante-dix étudiants ont répondu au questionnaire (taux de participation = 14 %). Le sex-ratio était de 1,84. L’âge moyen était de 20,7 ans [19–35]. Au total, 781 étudiants étaient des consommateurs de cannabis (20 %), 170 d’ecstasy (4,4 %), 58 de cocaïne (1,4 %) et 5 d’héroïne (0,1 %). Cent soixante-cinq étudiants ont indiqué qu’ils utilisaient des médicaments sans prescription médicale ou de façon excessive. Parmi eux 43 étaient des consommateurs d’opioïdes (88 % de codéine) et 27 étaient des consommateurs de benzodiazépines (dont deux tiers consommaient de l’alprazolam). Les patients présentant un mésusage s’avèrent plus à risque d’utiliser des substances psychoactives illégales (cannabis ROR = 2,82 [2,04–3,9], ecstasy ROR = 4,38 [2,76–6,96], cocaïne ROR = 6,58 [3,42–12,67] et héroïne ROR = 96,99 [10,78–872,2]). De plus un état anxieux est fréquemment retrouvé (47,2 %) de même qu’une mauvaise qualité de sommeil (38,8 %).DiscussionL’état anxieux et la mauvaise qualité du sommeil observés en population estudiantine peuvent en partie expliquer le besoin de certains étudiants de mésuser benzodiazépines et opiacés. D’autres veulent améliorer leurs performances ce qui explique la proportion de 22,43 % d’usagers de psychostimulants. Ces résultats sont similaires à ceux retrouvés dans l’enquête ESCAPAD 2014 à l’exception de la cocaïne (1,4 % dans ADUC contre 3,2 %). Ils mettent en lumière que la politique de santé et plus particulièrement la prévention de l’usage des substances psychoactives à l’université est toujours un challenge majeur. De façon intéressante la codéine et l’alprazolam sont les médicaments les plus mésusés par la population estudiantine. L’enquête ADUC nous permettra d’étudier l’impact des récentes restrictions dans la prescription et la délivrance des médicaments à base de codéine en juillet 2017 et de certaines benzodiazépines en 2016