Evaluation et auto-évaluation des niveaux et des variations de l'attention de l'enfant à l'adulte: approche chronopsychologique

International audienceLes variations journalières des processus cognitifs en situation d'apprentissage ont fait l'objet de nombreux travaux chez l'enfant scolarisé. Parmi ces processus, l'implication majeure de l'attention depuis la perception jusqu'à l'action est acquise. Concernant les rythmicités cognitives de l'adulte en formation, la littérature présente peu de travaux repérables dans ce milieu de vie et de développement. Par ailleurs, si les performances mesurées ont largement été investies dans l'étude des rythmicités cognitives de l'enfant à l'adulte, l'auto estimation reste elle-même peu étudiée. Le but poursuivi était d'évaluer les niveaux et les variations journalières de l'attention mesurée et auto-estimée de l'enfant à l'adulte selon une perspective développementale et d'investir les écarts entre mesures objectives et subjectives. Participants : 262 enfants scolarisés du CP au CM2 : 134 filles (âge moyen : 9 ± 2) ; 128 garçons (âge moyen : 9 ± 1), et 166 adultes en formation : 130 femmes (âge moyen : 31;2 ± 10) et 36 hommes (âge moyen : 27;10 ± 8). Matériel et déroulement : Tests de barrage et échelles visuelles analogiques (fatigue et vigilance) en passation collective à quatre moments d'une même journée (début et fin de matinée ; début et fin d'après-midi) au mois de mai. Les données ont été traitées par ANOVA à mesures répétées, analyses corrélationnelles et typologiques. Les analyses suggèrent la mise en place progressive d'un profil journalier de l'attention avec élévation des performances du début de la journée jusqu'en fin d'après-midi pour l'adulte. Ainsi le profil classique défini chez l'enfant constituerait une étape dans le développement de l'attention de l'enfant à l'adulte. Le creux post prandial observé dans la littérature chez les enfants semble disparaître avec l'avancée en âge et l'existence de profils différenciés chez les plus jeunes contraste avec la typologie des adultes principalement caractérisée par des différences de niveau d'attention sans différenciation de profil. Aucun effet du genre n'a été relevé quel que soit l'âge considéré. Si la mesure subjective de la vigilance n'est pas prédictive des performances attentionnelles et de leurs variations, elle est en lien avec l'autoévaluation de la fatigue suggérant l'effort fourni et ressenti pour maintenir les performances. Les relations entre mesures objectives et subjectives et leurs variations journalières ouvrent un champ nouveau à investir pour les travaux en chronopsychologie dans une perspective life span

Root-root interactions: extending our perspective to be more inclusive of the range of theories in ecology and agriculture using in-vivo analyses

Background There is a large body of literature on competitive interactions among plants, but many studies have only focused on above-ground interactions and little is known about root-root dynamics between interacting plants. The perspective on possible mechanisms that explain the outcome of root-root interactions has recently been extended to include non-resource-driven mechanisms (as well as resource-driven mechanisms) of root competition and positive interactions such as facilitation. These approaches have often suffered from being static, partly due to the lack of appropriate methodologies for in-situ non-destructive root characterization. Scope Recent studies show that interactive effects of plant neighbourhood interactions follow non-linear and non-additive paths that are hard to explain. Common outcomes such as accumulation of roots mainly in the topsoil cannot be explained solely by competition theory but require a more inclusive theoretical, as well as an improved methodological framework. This will include the question of whether we can apply the same conceptual framework to crop versus natural species. Conclusions The development of non-invasive methods to dynamically study root-root interactions in vivo will provide the necessary tools to study a more inclusive conceptual framework for root-root interactions. By following the dynamics of root-root interactions through time in a whole range of scenarios and systems, using a wide variety of non-invasive methods, (such as fluorescent protein which now allows us to separately identify the roots of several individuals within soil), we will be much better equipped to answer some of the key questions in root physiology, ecology and agronom

Brain Struct Funct

Opioid receptors are G protein-coupled receptors (GPCRs) that modulate brain function at all levels of neural integration, including autonomic, sensory, emotional and cognitive processing. Mu (MOR) and delta (DOR) opioid receptors functionally interact in vivo, but whether interactions occur at circuitry, cellular or molecular levels remains unsolved. To challenge the hypothesis of MOR/DOR heteromerization in the brain, we generated redMOR/greenDOR double knock-in mice and report dual receptor mapping throughout the nervous system. Data are organized as an interactive database offering an opioid receptor atlas with concomitant MOR/DOR visualization at subcellular resolution, accessible online. We also provide co-immunoprecipitation-based evidence for receptor heteromerization in these mice. In the forebrain, MOR and DOR are mainly detected in separate neurons, suggesting system-level interactions in high-order processing. In contrast, neuronal co-localization is detected in subcortical networks essential for survival involved in eating and sexual behaviors or perception and response to aversive stimuli. In addition, potential MOR/DOR intracellular interactions within the nociceptive pathway offer novel therapeutic perspectives

Disentangling who is who during rhizosphere acidification in root interactions: combining fluorescence with optode techniques

Plant–soil interactions can strongly influence root growth in plants. There is now increasing evidence that root–root interactions can also influence root growth, affecting architecture and root traits such as lateral root formation. Both when species grow alone or in interaction with others, root systems are in turn affected by as well as affect rhizosphere pH. Changes in soil pH have knock-on effects on nutrient availability. A limitation until recently has been the inability to assign species identity to different roots in soil. Combining the planar optode technique with fluorescent plants enables us to distinguish between plant species grown in natural soil and in parallel study pH dynamics in a non-invasive way at the same region of interest (ROI). We measured pH in the rhizosphere of maize and bean in rhizotrons in a climate chamber, with ROIs on roots in proximity to the roots of the other species as well as not-close to the other species. We found clear dynamic changes of pH over time and differences between the two species in rhizosphere acidification. Interestingly, when roots of the two species were interacting, the degree of acidification or alkalization compared to bulk soil was less strong then when roots were not growing in the vicinity of the other species. This cutting-edge approach can help provide a better understanding of plant–plant and plant–soil interactions

Novel multiscale insights into the composite nature of water transport in roots

MECHA is a novel mathematical model that computes the flow of water through the walls, membranes and plasmodesmata of each individual cell throughout complete root cross-sections, from a minimal set of cell level hydraulic properties and detailed root anatomical descriptions. Using the hydraulic anatomical framework of the Zea mays root reveals that hydraulic principles at the cell and root segment scales, derived independently by Katchalsky and Curran [1967] and Fiscus and Kramer [1975], are fully compatible, irrespective of apoplastic barriers leakiness. The hydraulic anatomy model accurately predicts empirical root radial permeability (kr) from relatively high cell wall hydraulic conductivity and low plasmodesmatal conductance reported in the literature. MECHA brings novel insights into contradictory interpretations of experiments from the literature by quantifying the impact of intercellular spaces, cortical cell permeability and plasmodesmata among others on root kr, and suggests new experiments efficiently addressing questions of root water relations

An upscaling model describing root radial hydraulic conductivity from cross section anatomy and aquaporin expression patterns

Objectives: To improve our understanding of aquaporin (AQP) expression patterns and root anatomy effects on radial hydraulic conductivity by combining quantitative in vivo and in silico experiments from the cell to the root cross-section scales in various hydric environments. Methods: A program generates explicit 2D root cross-section hydraulic networks from cross-section anatomy images. The hydraulic network includes "cell wall" and "intra cell" nodes constituting connected pathways allowing water flow from the root surface to xylem vessels using the transmembrane, apoplastic and symplastic pathways. Cell layers have hydraulic properties that depend on plasma membrane AQP abundance and apoplastic barrier deposition. Water flow equations are solved to compute water potentials and fluxes in each node of the system. The radial hydraulic conductivity of the root cross section can then be calculated. Results: We created a mathematical model linking the radial conductivities of root segments to a minimal set of quantitative molecular (AQP expression) and explicit anatomical data. The model distinguishes apoplastic, symplastic and transmembrane pathways within the root tissues and integrates the temporal scales of AQP regulation and apoplastic barrier formation which drive root hydraulic properties. Interpretation: The data obtained during the project lead to a better understanding of the constraints that drive AQP expression patterns and apoplastic barrier deposition. This new model is intended to replace the empirical rules that were used in pioneer models of water dynamics in the soil-plant system. It is expected to become a tool that will bridge the gap between protein regulatory pathways operating at the cell level, hydraulic behaviour at higher levels and strategies of plant water use, which constraints the success of crop water acquisition in various drought scenarios