Contrôle actif de mouvement et rôle de l'agentivité en environnement ambigu

Self-motion perception is a key factor in daily behaviours such as driving a car or piloting an aircraft. It is mainly based on visuo-vestibular integration, whose weighting mechanisms are modulated by the reliability properties of sensory inputs. Recently, it has been shown that the internal state of the operator can also modulate multisensory integration and may sharpen the representation of relevant inputs. In line with the concept of agency, it thus appears relevant to evaluate the impact of being in control of our own action on self-motion perception. Here, we tested two conditions of motion control (active/manual trigger versus passive/observer condition), asking participants to discriminate between two consecutive longitudinal movements by identifying the larger displacement (displacement of higher intensity). We also tested motion discrimination under two levels of ambiguity by applying acceleration ratios that differed from our two “standard” displacements (i.e., 3 sec; 0.012 m.s-2 and 0.030 m.s-2 ). We found an effect of control condition, but not of the level of ambiguity on the way participants perceived the standard displacement, i.e. perceptual bias (Point of Subjective Equality; PSE). Also, we found a significant effect of interaction between the active condition and the level of ambiguity on the ability to discriminate between displacements, i.e. sensitivity (Just Noticeable Difference; JND). Being in control of our own motion through a manual intentional trigger of self-displacement maintains overall motion sensitivity when ambiguity increases.La perception du mouvement propre est un facteur clé dans les comportements quotidiens tels que la conduite d'une voiture ou le pilotage d'un avion. Elle repose principalement sur l'intégration visuo-vestibulaire, dont les mécanismes de pondération sont modulés par les propriétés de fiabilité des entrées sensorielles. Récemment, il a été démontré que l'état interne de l'opérateur peut également moduler l'intégration multisensorielle et affiner la représentation des données pertinentes. En accord avec le concept d'"agency", il semble donc pertinent d'évaluer l'impact du contrôle de notre propre action sur la perception du mouvement propre. Ici, nous avons testé deux conditions de contrôle du mouvement (déclencheur actif/manuel contre condition passive/observateur), en demandant aux participants de distinguer deux mouvements longitudinaux consécutifs en identifiant le déplacement le plus important (déplacement de plus forte intensité). Nous avons également testé la discrimination des mouvements selon deux niveaux d'ambiguïté en appliquant des rapports d'accélération différents de nos deux déplacements "standard" (c'est-à-dire 3 secondes ; 0,012 m.s-2 et 0,030 m.s-2 ). Nous avons constaté un effet de la condition de contrôle, mais pas du niveau d'ambiguïté, sur la manière dont les participants percevaient le déplacement standard, c'est-à-dire le biais perceptif (point d'égalité subjective ; PSE). Nous avons également constaté un effet significatif de l'interaction entre la condition active et le niveau d'ambiguïté sur la capacité à distinguer les déplacements, c'est-à-dire la sensibilité (Just Noticeable Difference ; JND). Le fait de contrôler son propre mouvement par le biais d'un déclenchement manuel intentionnel maintient la sensibilité globale au mouvement lorsque l'ambiguïté augmente

Être actif sur son propre mouvement : Considérer les mécanismes prédictifs dans la perception du mouvement propre

Self-motion perception is a key element guiding pilots' behavior. Its importance is mostly revealed when impaired, leading in most cases to spatial disorientation which is still today a major factor of accidents occurrence. Self-motion perception is known as mainly based on visuo-vestibular integration and can be modulated by the physical properties of the environment with which humans interact. For instance, several studies have shown that the respective weight of visual and vestibular information depends on their reliability. More recently, it has been suggested that the internal state of an operator can also modulate multisensory integration. Interestingly, the systems' automation can interfere with this internal state through the loss of the intentional nature of movements (i.e., loss of agency) and the modulation of associated predictive mechanisms. In this context, one of the new challenges is to better understand the relationship between automation and self-motion perception. The present review explains how linking the concepts of agency and self-motion is a first approach to address this issue.La perception du mouvement propre est un élément clé qui guide le comportement des pilotes. Son importance se révèle surtout lorsqu'elle est altérée, entraînant dans la plupart des cas une désorientation spatiale qui est encore aujourd'hui un facteur majeur d'accidents. La perception de l'auto-mouvement est connue comme étant principalement basée sur l'intégration visuo-vestibulaire et peut être modulée par les propriétés physiques de l'environnement avec lequel les humains interagissent. Par exemple, plusieurs études ont montré que le poids respectif des informations visuelles et vestibulaires dépend de leur fiabilité. Plus récemment, il a été suggéré que l'état interne d'un opérateur peut également moduler l'intégration multisensorielle. Il est intéressant de noter que l'automatisation des systèmes peut interférer avec cet état interne par la perte du caractère intentionnel des mouvements (c'est-à-dire la perte d'agence) et la modulation des mécanismes prédictifs associés. Dans ce contexte, l'un des nouveaux défis est de mieux comprendre la relation entre l'automatisation et la perception du mouvement propre. La présente revue explique comment le fait de relier les concepts d'agentivité et d'intégration multisensorielle constitue une première approche pour aborder cette question

Epigenetic and Transcriptomic Programming of HSC Quiescence Signaling in Large for Gestational Age Neonates

Excessive fetal growth is associated with DNA methylation alterations in human hematopoietic stem and progenitor cells (HSPC), but their functional impact remains elusive. We implemented an integrative analysis combining single-cell epigenomics, single-cell transcriptomics, and in vitro analyses to functionally link DNA methylation changes to putative alterations of HSPC functions. We showed in hematopoietic stem cells (HSC) from large for gestational age neonates that both DNA hypermethylation and chromatin rearrangements target a specific network of transcription factors known to sustain stem cell quiescence. In parallel, we found a decreased expression of key genes regulating HSC differentiation including EGR1, KLF2, SOCS3, and JUNB. Our functional analyses showed that this epigenetic programming was associated with a decreased ability for HSCs to remain quiescent. Taken together, our multimodal approach using single-cell (epi)genomics showed that human fetal overgrowth affects hematopoietic stem cells’ quiescence signaling via epigenetic programming

PanGeneHome : A Web Interface to Analyze Microbial Pangenomes

International audiencePanGeneHome is a web server dedicated to the analysis of available microbial pangenomes. For any prokaryotic taxon with at least three sequenced genomes, PanGeneHome provides (i) conservation level of genes, (ii) pangenome and core-genome curves, estimated pangenome size and other metrics, (iii) dendrograms based on gene content and average amino acid identity (AAI) for these genomes, and (iv) functional categories and metabolic pathways represented in the core, accessory and unique gene pools of the selected taxon. In addition, the results for these different analyses can be compared for any set of taxa. With the availability of 615 taxa, covering 182 species and 49 orders, PanGeneHome provides an easy way to get a glimpse on the pangenome of a microbial group of interest. The server and its documentation are available at http://pangenehome.lmge.uca.fr

New tectonic configuration in NE Iran: Active strike-slip faulting between the Kopeh Dagh and Binalud mountains

International audienceIn this paper, a combined approach of geomorphic analyses, detailed geological mapping on SPOT 5 satellite images and field surveys, complemented by radiometric dating (Ar-40/Ar-39) allows proposing a new and consistent tectonic configuration for the northeastern Arabia-Eurasia collision zone. It favors a simple strike-slip faulting mechanism in NE Iran accommodating the northward motion of central Iran with respect to Eurasia between the Binalud and Kopeh Dagh mountains. Our results demonstrate that similar to 2 mm/a (similar to 25%) of this northward motion has been transferred from the Binalud to the Kopeh Dagh through the Meshkan Transfer Zone since similar to 5 Ma. The modern state of stress deduced from fault kinematics analyses shows N30 degrees E trending maximum stress axis and confirms a dominant strike-slip faulting mechanism. Combining our geological data with other available data, we conclude that kinematics of deformation can be appropriately described by rigid block faulting in NE Iran; instead, the continuous deformation as it has been thought during the last 3 decades

Pharmacological HDAC inhibition impairs pancreatic β-cell function through an epigenome-wide reprogramming

Summary: Histone deacetylases enzymes (HDACs) are chromatin modifiers that regulate gene expression through deacetylation of lysine residues within specific histone and non-histone proteins. A cell-specific gene expression pattern defines the identity of insulin-producing pancreatic β cells, yet molecular networks driving this transcriptional specificity are not fully understood. Here, we investigated the HDAC-dependent molecular mechanisms controlling pancreatic β-cell identity and function using the pan-HDAC inhibitor trichostatin A through chromatin immunoprecipitation assays and RNA sequencing experiments. We observed that TSA alters insulin secretion associated with β-cell specific transcriptome programming in both mouse and human β-cell lines, as well as on human pancreatic islets. We also demonstrated that this alternative β-cell transcriptional program in response to HDAC inhibition is related to an epigenome-wide remodeling at both promoters and enhancers. Our data indicate that HDAC activity could be required to protect against loss of β-cell identity with unsuitable expression of genes associated with alternative cell fates