44 research outputs found

    Involvement of Basal Ganglia Network in Motor Disabilities Induced by Typical Antipsychotics

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    BACKGROUND:Clinical treatments with typical antipsychotic drugs (APDs) are accompanied by extrapyramidal motor side-effects (EPS) such as hypokinesia and catalepsy. As little is known about electrophysiological substrates of such motor disturbances, we investigated the effects of a typical APD, alpha-flupentixol, on the motor behavior and the neuronal activity of the whole basal ganglia nuclei in the rat. METHODS AND FINDINGS:The motor behavior was examined by the open field actimeter and the neuronal activity of basal ganglia nuclei was investigated using extracellular single unit recordings on urethane anesthetized rats. We show that alpha-flupentixol induced EPS paralleled by a decrease in the firing rate and a disorganization of the firing pattern in both substantia nigra pars reticulata (SNr) and subthalamic nucleus (STN). Furthermore, alpha-flupentixol induced an increase in the firing rate of globus pallidus (GP) neurons. In the striatum, we recorded two populations of medium spiny neurons (MSNs) after their antidromic identification. At basal level, both striato-pallidal and striato-nigral MSNs were found to be unaffected by alpha-flupentixol. However, during electrical cortico-striatal activation only striato-pallidal, but not striato-nigral, MSNs were found to be inhibited by alpha-flupentixol. Together, our results suggest that the changes in STN and SNr neuronal activity are a consequence of increased neuronal activity of globus pallidus (GP). Indeed, after selective GP lesion, alpha-flupentixol failed to induce EPS and to alter STN neuronal activity. CONCLUSION:Our study reports strong evidence to show that hypokinesia and catalepsy induced by alpha-flupentixol are triggered by dramatic changes occurring in basal ganglia network. We provide new insight into the key role of GP in the pathophysiology of APD-induced EPS suggesting that the GP can be considered as a potential target for the treatment of EPS

    Molecular effects of resistance elicitors from biological origin and their potential for crop protection

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    Plants contain a sophisticated innate immune network to prevent pathogenic microbes from gaining access to nutrients and from colonising internal structures. The first layer of inducible response is governed by the plant following the perception of microbe- or modified plant-derived molecules. As the perception of these molecules results in a plant response that can provide efficient resistance towards non-adapted pathogens they can also be described as ‘defence elicitors’. In compatible plant/microbe interactions, adapted microorganisms have means to avoid or disable this resistance response and promote virulence. However, this requires a detailed spatial and temporal response from the invading pathogens. In agricultural practice, treating plants with isolated defence elicitors in the absence of pathogens can promote plant resistance by uncoupling defence activation from the effects of pathogen virulence determinants. The plant responses to plant, bacterial, oomycete or fungal-derived elicitors are not, in all cases, universal and need elucidating prior to the application in agriculture. This review provides an overview of currently known elicitors of biological rather than synthetic origin and places their activity into a molecular context

    Berry Flesh and Skin Ripening Features in Vitis vinifera as Assessed by Transcriptional Profiling

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    Background Ripening of fleshy fruit is a complex developmental process involving the differentiation of tissues with separate functions. During grapevine berry ripening important processes contributing to table and wine grape quality take place, some of them flesh- or skin-specific. In this study, transcriptional profiles throughout flesh and skin ripening were followed during two different seasons in a table grape cultivar ‘Muscat Hamburg’ to determine tissue-specific as well as common developmental programs. Methodology/Principal Findings Using an updated GrapeGen Affymetrix GeneChipÂź annotation based on grapevine 12×v1 gene predictions, 2188 differentially accumulated transcripts between flesh and skin and 2839 transcripts differentially accumulated throughout ripening in the same manner in both tissues were identified. Transcriptional profiles were dominated by changes at the beginning of veraison which affect both pericarp tissues, although frequently delayed or with lower intensity in the skin than in the flesh. Functional enrichment analysis identified the decay on biosynthetic processes, photosynthesis and transport as a major part of the program delayed in the skin. In addition, a higher number of functional categories, including several related to macromolecule transport and phenylpropanoid and lipid biosynthesis, were over-represented in transcripts accumulated to higher levels in the skin. Functional enrichment also indicated auxin, gibberellins and bHLH transcription factors to take part in the regulation of pre-veraison processes in the pericarp, whereas WRKY and C2H2 family transcription factors seems to more specifically participate in the regulation of skin and flesh ripening, respectively. Conclusions/Significance A transcriptomic analysis indicates that a large part of the ripening program is shared by both pericarp tissues despite some components are delayed in the skin. In addition, important tissue differences are present from early stages prior to the ripening onset including tissue-specific regulators. Altogether, these findings provide key elements to understand berry ripening and its differential regulation in flesh and skin.This study was financially supported by GrapeGen Project funded by Genoma España within a collaborative agreement with Genome Canada. The authors also thank The Ministerio de Ciencia e Innovacion for project BIO2008-03892 and a bilateral collaborative grant with Argentina (AR2009-0021). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

    The neural bases of decision learning in the basal ganglia : an electrophysiological and behavioral approach in the non-human primate

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    Une question fondamentale en neuroscience, ainsi que dans de nombreuses disciplines s’intĂ©ressant Ă  la comprĂ©hension du comportement, telles que la psychologie, l’Economie, et la sociologie, concerne les processus dĂ©cisionnels par lesquels les animaux et les humains sĂ©lectionnent des actions renforcĂ©es positivement ou nĂ©gativement. Les processus dĂ©cisionnels ainsi que leur base neuronale demeurent mal compris. D’autre part de nombreuses Ă©tudes ont rĂ©vĂ©lĂ© que les humains ainsi que les animaux prennent souvent des dĂ©cisions sous-optimales. Notre principal objectif a Ă©tĂ© de comprendre la raison de ces comportements sous-optimaux. Par ailleurs, l’altĂ©ration des processus sous-tendant la prise de dĂ©cision, entraĂźne des pathologies. La comprĂ©hension des mĂ©canismes dĂ©cisionnels est essentielle au dĂ©veloppement de stratĂ©gies de traitements plus efficaces. Dans cette Ă©tude nous avons proposĂ© une nouvelle approche de l’étude des comportements dĂ©cisionnels, basĂ©e sur l’hĂ©tĂ©rogĂ©nĂ©itĂ© des prĂ©fĂ©rences crĂ©Ă©es au cours de l’apprentissage du choix. Puis nous avons corrĂ©lĂ© l’activitĂ© du putamen et du globus pallidus interne aux comportements prĂ©alablement dĂ©crits. Nos rĂ©sultats montrent que bien que les primates apprennent Ă  identifier la meilleure option et convergent vers une stratĂ©gie optimale dans un nombre important de sessions, ils n’arrivent pas en moyenne Ă  optimiser leur comportement. Nous avons montrĂ© que ce comportement suboptimal des primates est caractĂ©risĂ© par la crĂ©ation de prĂ©fĂ©rences irrationnelles par ces derniers pour des paramĂštres non pertinents de l’environnement. Nous avons finalement montrĂ© que bien qu’un faible nombre de neurones du putamen encode la valeur de l’action, leur contribution Ă  l’activitĂ© de population est faible. L’activitĂ© du putamen reflĂšte les futures performances des primates et prĂ©dit donc la formation des comportements irrationnels et rationnels.A fundamental question in neuroscience, as well as in various fields such as economics, psychology and sociology, concerns the decision making processes by which animals and humans select actions based on reward and punishment. Both decision making processes and their neural basis are still poorly understood. Also, both human and animals often make suboptimal decisions in many tasks studied. Our first aim is to improve the understanding of why such sub-optimal decisions are made. Also, the alteration of decision making processes causes diseases, the understanding of whose mechanisms is essential in developing better treatment strategies. In this report, we propose a new approach which consists in extracting the neural substrates of choice behavior heterogeneity in between sessions. Our results show that although primates learn on average to identify the best option and converge to an optimal policy in a consequent number of sessions, they fail on average to optimize their behavior. We revealed that this suboptimal behavior was characterized by an unexpected high behavioral heterogeneity during the task that was due to the creation of irrelevant preferences by the monkeys. We finally show that although a few neurons of the putamen encode the action value, their contribution to the overall population activity is weak. Putamen activity rather reflects the futures performances and predicts the creation of rational and irrational behaviors

    Contributions of cortical and subcortical oscillations during reactive task switching

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    Le task switching est la capacitĂ© Ă  reconfigurer rapidement un ensemble de processus cognitifs permettant la rĂ©alisation d’une tache (cet ensemble de processus est appelĂ© task-set). La littĂ©rature animale indique que des neurones dans un rĂ©seau composĂ© du cortex dorso-mĂ©dian et du noyau sous-thalamique augmentent leurs activitĂ©s lors d’un changement de task-set en rĂ©ponse Ă  un stimulus visuel. Toutefois, chez l’homme, ladynamique prĂ©cise du rĂ©seau dĂ©cisionnaire lors du task switching reste peu connue en raison d’un manque relatif de donnĂ©es Ă©lectrophysiologiques directes. L’objectif de cette thĂšse est d’étudier les signaux intracrĂąniens obtenus soit chez des patients prĂ©sentant des troubles obsessionnels compulsifs sĂ©vĂšres soit chez des patients Ă©pileptiques pharmaco-rĂ©sistants pendant que les participants rĂ©alisaient des paradigmes de task switching.Dans une premiĂšre Ă©tude, nous montrons une augmentation de puissance dans les bandes de frĂ©quences thĂȘta (5-10Hz), bĂȘta (15-35Hz) et gamma (60-200Hz) peu de temps aprĂšs un changement de rĂšgle. Les associations entre le comportement et ces bandes de frĂ©quences suggĂšrent qu’elles jouent un rĂŽle distinct. En se basant sur un modĂšle de drift diffusion (DDM), nous avons observĂ© que cette diffĂ©rence en temps de rĂ©action et taux d’erreur Ă©tait le rĂ©sultat d’un niveau d’évidence plus faible au dĂ©but des essais correspondant Ă  un changement de task-set. De plus, en introduisant la bande de frĂ©quence thĂȘta comme modulateur du niveau d’évidence initial, une association nĂ©gative existait et permettait d’expliquer la relation non-linĂ©aire entre les activitĂ©s thĂȘta et le comportement. Les rĂ©sultats obtenus suggĂšrent donc que les modulations de puissancedans la bande de frĂ©quence thĂȘta du noyau sous-thalamique et du cortex dorso-mĂ©dial prĂ©frontal sont critiques dans le processus de task switching.Les rĂ©sultats prĂ©liminaires d’une seconde Ă©tude indiquent que l’activitĂ© thĂȘta, mesurĂ©e Ă  une latence courte (<200 ms) aprĂšs un changement de rĂšgle et avant les processus permettant de sĂ©lectionner l’action, augmente dans un rĂ©seau temporo-parieto insulaire et cingulaire lors des changements de tĂąche.Dans l’ensemble, cette thĂšse apporte les premiĂšres Ă©vidences intracĂ©rĂ©brales durant les processus cognitifs associĂ©s au task switching.Task switching is the ability to rapidly reconfigure a set of cognitive processes (called task set) that allow the completion of a task. The animal literature indicates that neurons in a network composed of the dorsomedial cortex and the subthalamic nucleus increase their activities when a task set switches in response to a visual stimulus. However, in humans, the precise dynamic of the decision network during task switching remain poorly understood due to a relative lack of direct electrophysiological recordings. The aim of this thesis is to study intracranial signals obtained either in patients with severe obsessive-compulsive disorder or in drug-resistant epileptic patients while the participants were performing task switching paradigms.In a first study, we show an increase in power in the theta (5-10Hz), beta (15-35Hz) and gamma (60-200Hz) frequency bands shortly after a rule switching. The associations between behavior and these frequency bands suggest that they play a distinct role. Based on a drift diffusion model (DDM), we observed that this difference in reaction time and error rate was the result of a lower level of evidence at the beginning of trials corresponding to a change of task set. Moreover, by introducing the theta frequency band as a modulator of the initial level of evidence, a negative association existed and allowed us to explain the non-linear relationship between theta activities and behavioral performances. These results thus suggest that power modulations in the theta frequency band of the subthalamic nucleus and dorsomedial prefrontal cortex are critical in the task switching process.Preliminary results from a second study indicate that theta activity, measured shortly after a rule switching (<200 ms) and before processes facilitating the action selection the action, increase in a temporo-parieto insular and cingulate network during task changes.Overall, this thesis provides the first intracerebral evidence during the cognitive processes associated with task switching

    The neural bases of decision learning in the basal ganglia : an electrophysiological and behavioral approach in the non-human primate

    No full text
    Une question fondamentale en neuroscience, ainsi que dans de nombreuses disciplines s’intĂ©ressant Ă  la comprĂ©hension du comportement, telles que la psychologie, l’Economie, et la sociologie, concerne les processus dĂ©cisionnels par lesquels les animaux et les humains sĂ©lectionnent des actions renforcĂ©es positivement ou nĂ©gativement. Les processus dĂ©cisionnels ainsi que leur base neuronale demeurent mal compris. D’autre part de nombreuses Ă©tudes ont rĂ©vĂ©lĂ© que les humains ainsi que les animaux prennent souvent des dĂ©cisions sous-optimales. Notre principal objectif a Ă©tĂ© de comprendre la raison de ces comportements sous-optimaux. Par ailleurs, l’altĂ©ration des processus sous-tendant la prise de dĂ©cision, entraĂźne des pathologies. La comprĂ©hension des mĂ©canismes dĂ©cisionnels est essentielle au dĂ©veloppement de stratĂ©gies de traitements plus efficaces. Dans cette Ă©tude nous avons proposĂ© une nouvelle approche de l’étude des comportements dĂ©cisionnels, basĂ©e sur l’hĂ©tĂ©rogĂ©nĂ©itĂ© des prĂ©fĂ©rences crĂ©Ă©es au cours de l’apprentissage du choix. Puis nous avons corrĂ©lĂ© l’activitĂ© du putamen et du globus pallidus interne aux comportements prĂ©alablement dĂ©crits. Nos rĂ©sultats montrent que bien que les primates apprennent Ă  identifier la meilleure option et convergent vers une stratĂ©gie optimale dans un nombre important de sessions, ils n’arrivent pas en moyenne Ă  optimiser leur comportement. Nous avons montrĂ© que ce comportement suboptimal des primates est caractĂ©risĂ© par la crĂ©ation de prĂ©fĂ©rences irrationnelles par ces derniers pour des paramĂštres non pertinents de l’environnement. Nous avons finalement montrĂ© que bien qu’un faible nombre de neurones du putamen encode la valeur de l’action, leur contribution Ă  l’activitĂ© de population est faible. L’activitĂ© du putamen reflĂšte les futures performances des primates et prĂ©dit donc la formation des comportements irrationnels et rationnels.A fundamental question in neuroscience, as well as in various fields such as economics, psychology and sociology, concerns the decision making processes by which animals and humans select actions based on reward and punishment. Both decision making processes and their neural basis are still poorly understood. Also, both human and animals often make suboptimal decisions in many tasks studied. Our first aim is to improve the understanding of why such sub-optimal decisions are made. Also, the alteration of decision making processes causes diseases, the understanding of whose mechanisms is essential in developing better treatment strategies. In this report, we propose a new approach which consists in extracting the neural substrates of choice behavior heterogeneity in between sessions. Our results show that although primates learn on average to identify the best option and converge to an optimal policy in a consequent number of sessions, they fail on average to optimize their behavior. We revealed that this suboptimal behavior was characterized by an unexpected high behavioral heterogeneity during the task that was due to the creation of irrelevant preferences by the monkeys. We finally show that although a few neurons of the putamen encode the action value, their contribution to the overall population activity is weak. Putamen activity rather reflects the futures performances and predicts the creation of rational and irrational behaviors

    A switching observer for human perceptual estimation. Laquitaine et al

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    Data are sorted by task (Direction task with four priors, one prior and Spatial Orientation task) and subjects subXXX. Each matlab file contains Data for an experimental block of about 200 trials

    Microorganisms for soil treatment.

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    Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic
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