Est-ce que la musique améliore les performances de mémoire chez des patients atteints de trouble cognitif léger de type amnésiques ?

editorial reviewedL’exploitation des capacités préservées constitue l’une des interventions neuropsychologiques les plus répandues pour les troubles cognitifs d’origine neurodégénérative. La mémoire musicale semble préservée aux stades précoces de la maladie d'Alzheimer [1]. Dans cette étude, nous testons le potentiel bénéfice de la musique dans l'encodage en mémoire des patients atteints de troubles cognitifs légers (“amnestic Mild Cognitive Impairment”, aMCI). Inspirés par [2], nous avons créé une tâche, impliquant l’écoute de 38 textes courts évoquant des activités quotidiennes, présentés sous forme parlée ou chantée (19/modalité). Ensuite, un test de reconnaissance sur le thème général et sur les informations spécifiques des textes est réalisé. Nous comparons les performances entre volontaires âgés sains et patients aMCI. Les résultats ci-présents concernent les données acquises jusque-là : 36 contrôles et 18 aMCI (sur les 40 participants/groupe prévus d’ici la fin de l’étude). La moitié des participants réalise un jugement méta-mnésique additionnel (“Judgment of Leaning”, JoL) en prédisant leur probabilité de se rappeler du texte. Quatre ANOVAs mixtes comparant les groupes (contrôle vs. aMCI) et les modalités (chantée vs. parlée) sont réalisées séparément selon la présence ou non de JoL, et avec le pourcentage de succès pour la reconnaissance du thème général ou des informations spécifiques comme variable dépendante. Comme attendu, la musique n’a pas montré d’effet significatif sur la reconnaissance d’informations spécifiques (basée sur la recollection), ni d’interaction significative avec le groupe malgré un effet principal du groupe indiquant une performance significativement inférieure pour les aMCI (p=.014 avec JoL et p<.001 sans). Cependant, pour la reconnaissance du thème général (basée sur la familiarité) avec JoL, nous observons un effet significatif du groupe (p<.001) ainsi qu’une interaction significative avec la modalité (p=.036). Les analyses post-hocs révèlent une différence significative entre contrôles et aMCI quand les textes sont parlés (p<.001), mais pas chantés (p=.131). En conclusion, nos résultats préliminaires permettent de répliquer l’effet bénéfique de la musique sur les processus de familiarité, mais pas de recollection, corroborant [2]. De plus, nos résultats suggèrent que les performances mnésiques des patients aMCI pour le thème général se normalisent (gain moyen=10.5%) lorsque l’encodage en musique est combiné avec un jugement méta-mnésique

Effects of fluid preservation on sea star stable isotope compositions: Can museum collections be used for trophic ecology studies?

Stable isotope analyses (SIA) of carbon (δ13C) and nitrogen (δ15N) are a common tool to investigate the trophic ecology of marine organisms. After field sampling, animal tissues are usually preserved frozen or dried before subsequent analysis. However, museum samples, or samples not initially collected for SIA, are often fixed in preservative solutions. These preservation methods may alter stable isotope ratios in tissues and these effects should be quantified. Here, we investigated long-term effects (1, 3, 6, 9 and 12 months) of four preservation methods (freezing, alcohol, formaldehyde, drying) on δ13C and δ15N values of sea stars. In particular, we tried to assess the influence of preservation on the isotopic niches. We observed that only formaldehyde preservation significantly affected δ13C values, leading to strong reduction of the overlap between the isotopic niche of the fresh samples and those of the preserved samples. A correction factor was designed to manage this issue. δ15N values changed across time for all methods except freezing but this may be the result of a higher intra-individual variability of δ15N values. Bayesian estimations of the standard ellipse areas (SEAB) of preserved and fresh samples were not significantly different, except for the samples preserved 6 months in alcohol. These two results lead to reduction of the overlap between the isotopic niche of the fresh samples and those of the preserved samples across time. These preliminary results suggest that samples stored during one year in preservative fluids may be used for SIA. Future results will determine whether this can be generalised to sea stars preserved for a longer time, such as those in museum collections

Ammonium ion binding to DNA G-quadruplexes: do electrospray mass spectra faithfully reflect the solution-phase species?

International audienceG-quadruplex nucleic acids can bind ammonium ions in solution, and these complexes can be detected by electrospray mass spectrometry (ESI-MS). However, because ammonium ions are volatile, the extent to which ESI-MS quantitatively could provide an accurate reflection of such solution-phase equilibria is unclear. Here we studied five G-quadruplexes having known solution-phase structure and ammonium ion binding constants: the bimolecular G-quadruplexes (dG(4)T(4)G(4))(2), (dG(4)T(3)G(4))(2), and (dG(3)T(4)G(4))(2), and the intramolecular G-quadruplexes dG(4)(T(4)G(4))(3) and dG(2)T(2)G(2)TGTG(2)T(2)G(2) (thrombin binding aptamer). We found that not all mass spectrometers are equally suited to reflect the solution phase species. Ion activation can occur in the electrospray source, or in a high-pressure traveling wave ion mobility cell. When the softest instrumental conditions are used, ammonium ions bound between G-quartets, but also additional ammonium ions bound at specific sites outside the external G-quartets, can be observed. However, even specifically bound ammonium ions are in some instances too labile to be fully retained in the gas phase structures, and although the ammonium ion distribution observed by ESI-MS shows biases at specific stoichiometries, the relative abundances in solution are not always faithfully reflected. Ion mobility spectrometry results show that all inter-quartet ammonium ions are necessary to preserve the G-quadruplex fold in the gas phase. Ion mobility experiments, therefore, help assign the number of inner ammonium ions in the solution phase structure

Effects of fluid preservation on sea star stable isotope composition: do they prevent the use of museum collections for trophic ecology studies?

Stable isotope analyses (SIA) of carbon (δ13C) and nitrogen (δ15N) are now a common tool to investigate the trophic ecology of organisms and the functioning of food webs. After field sampling, organism tissues are usually preserved frozen or dried before subsequent analysis. However, museum samples, or samples not initially collected for SIA, are often fixed in preservative solutions such as formaldehyde or alcohol. These preservation methods may alter stable isotope ratios in tissues, making them difficult to interpret. Consequently, these effects should be quantified. Here, we investigated long-term effects of common preservation methods on δ13C and δ15N values of sea stars. In particular, we tried to assess the influence of preservation by comparing mean isotopic values and key isotopic niche metrics (standard ellipse area SEAC and SEAB, niche overlap) of fresh and preserved samples. Formaldehyde preservation significantly affected δ13C values, resulting in strong reduction of the overlap between the isotopic niche of the fresh samples and those of the preserved samples. However, after being altered, the mean δ13C value did not change over time. Consequently, a correction factor that can be used for any duration of preservation was designed. δ15N values changed across time for all methods except freezing but this may be the result of a higher intra-individual variability of δ15N values. Bayesian estimations of the standard ellipse areas (SEAB) of preserved and fresh samples were not significantly different, except for the samples preserved 6 months in alcohol. Nevertheless, these changes lead to reduction of the overlap between the isotopic niche of the fresh samples and those of the preserved samples across time. Future results will determine whether this can be generalised to sea stars preserved for a longer time. In particular, they will contribute determine whether museum samples, which have been collected during period when environmental conditions were different from today, may be used to study the past functioning of food webs

TSA, intervention psychomotrice et attention conjointe :perspectives d'évolution.

info:eu-repo/semantics/publishe