Le rôle du stade 2 du sommeil non-paradoxal et des fuseaux de sommeil dans la consolidation de la mémoire motrice séquentielle

De l’enfance au vieil âge, l’apprentissage moteur fait partie intégrale de notre vie de tous les jours. Suite à l’acquisition d’une nouvelle habileté motrice, notre cerveau continue d’en renforcer sa trace mnésique. Ce processus est mieux connu sous le nom de « consolidation de la mémoire », dans lequel le sommeil jouerait un rôle clé. Bien qu’il n’existe pas encore de consensus quant à savoir durant quel stade de sommeil ce processus à lieu, de plus en plus d’indices tendent à démontrer que les fuseaux de sommeil (FS) du stade 2 du sommeil non-paradoxal (SNP2) sont impliqués dans la consolidation. Néanmoins, ces résultats sont tous de nature corrélationnelle, seulement. Ainsi, le but de cette thèse est d’identifier le stade de sommeil durant lequel la consolidation d’une nouvelle mémoire motrice séquentielle à lieu et de définir le rôle des FS dans ce processus. Afin d’aborder ces objectifs, nous avons pairé une tâche d’apprentissage moteur séquentiel (AMS) à un paradigme olfactif de réactivation ciblée de la mémoire (RCM). Les participants ont été entrainés à la tâche d’AMS tout en étant exposé à une odeur. Cette même odeur leur a été présenté durant le sommeil afin de servir d’indice contextuel et ainsi réactiver la trace mnésique de la tâche nouvellement apprise. Enfin, au matin, leur niveau de consolidation a été mesuré à l’aide d’une session de retest à la même tâche. La première étude s’est intéressée au rôle des stades de sommeil principalement par la comparaison entre les gains en performance motrice entre les groupes indicés durant le stade de SNP2 ou de sommeil paradoxal (SP), ainsi que sur l’effet de l’indiçage sur les FS. Les résultats ont démontré que les participants conditionnés et indicés en stade de SNP2 avaient des gains en performance significativement plus élevés au retest que ceux indicés en SP ou ceux qui n’avaient pas été conditionnés à l’odeur. De plus, nous avons observé que l’indiçage entrainait des augmentations plus importantes en fréquence et amplitude des FS pariétaux chez le groupe indicé durant le SNP2. Finalement, nos résultats ont démontré que ces changements en fréquence prédisaient le degré des gains en performance des sujets. Au cours de la seconde étude nous avons exploré comment les FS pariétaux du SNP2 interagissaient avec différentes bandes de fréquence voisines localement et entre diverses régions corticales (connectivité). Les résultats ont démontré que la stimulation RCM avait instigué des augmentations d’activité concomitante dans des bandes de basse fréquence (delta [1-4 Hz], theta [4-8 Hz]) précédant et suivant les FS, et des augmentations dans la bande haut-bêta (25-30 Hz) pendant les FS. Ces changements ont été identifiés particulièrement au-dessus de régions corticales motrices et associatives. Nous avons aussi rapporté des hausses de la connectivité entre régions associées à l’apprentissage d’une tâche d’AMS, ainsi que des augmentations globales dans les bandes delta et thêta. Ensemble, ces deux études ont souligné l’importance du sommeil et de certains de ces constituants, c’est-à-dire le stade de SNP2 et les FS, dans la consolidation de mémoires motrices séquentielles. En effet, elles ont fait la démonstration qu’une nouvelle trace mnésique pouvait être réactivée et consolidée durant le SNP2 à l’aide d’un stimulus olfactif conditionné, menant ultimement à une performance motrice améliorée au-delà de ce qui est normalement observé, alors que le même effet est absent en SP. Cette thèse a établi que les FS sont instrumentaux au processus de consolidation bien que leur effet soit dépendant d’interrelations complexes locales et interrégionales avec d’autres bandes de fréquence, incluant le delta, thêta et haut-bêta. Ainsi, elle met les fondations pour une étude efficace du rôle des FS dans la consolidation de la mémoire au sein de leurs contextes temporal, topographique et fréquentiel.From infancy to old age, motor learning is part of our everyday life. After learning a new motor skill, our brain continues to reinforce its memory trace. This process is known as “memory consolidation”, in which sleep is thought to be a key period. However, there is still no consensus concerning the sleep stage when consolidation of a motor sequence memory trace takes place, although there is increasing evidence pointing towards stage-2 non-rapid eye movement (NREM2) sleep. Some of this evidence suggests that sleep spindles, hallmark features of NREM sleep, are associated with improvement in consolidation. Yet, these reports are only correlational in nature. Hence, the aim of this thesis is to identify the sleep stage during which motor sequence consolidation occurs and define the involvement of sleep spindles in this process. To tackle these objectives, we used a finger tapping task paired to an olfactory targeted memory reactivation (TMR) paradigm. Participants were trained to a motor sequence learning (MSL) task while being exposed to an odor. The same olfactory stimulus was used during sleep as a cue to reactivate the memory trace of the newly learned motor task. In the morning, consolidation was assessed through a retest session of the same task. The first study probed the role of sleep stages by comparing motor performance gains between groups cued in NREM2 and rapid eye movements (REM) sleep. It also assessed the effect of cuing on sleep spindles characteristics. Results showed that participants cued during NREM2 sleep showed greater gains in performance at retest than those cued during REM sleep or those not conditioned but exposed during NREM2 sleep. Furthermore, they demonstrated that cuing led to increases in frequency and amplitude of parietal sleep spindles only. Finally, we found that cue-related changes in specific spindle frequency bands predicted the overnight gains in performance. In the second study, building on our previous findings, we investigated how parietal NREM2 sleep spindles interact with other frequency bands locally and between cortical regions (connectivity). Results showed that TMR stimulation instigated increases of concomitant activity in lower frequency bands (delta [1-4 Hz], theta [4-8 Hz]) preceding and following spindles, and increases within the high-beta (25-30 Hz) band during spindles. These changes were found particularly over motor and associative areas. We also reported enhanced connectivity between task-related regions in the sigma band as well as widespread increases in the delta and theta bands. Together, both studies demonstrated the importance of sleep and its constituents, namely NREM2 sleep and spindles, in the consolidation of motor sequence memories. Indeed, they showed that the newly learned memory trace can be reinforced during NREM2 by the use of an olfactory stimulus leading ultimately to an enhanced motor performance in the morning over and above normal behaviour, while the same effect does not appear to occur with REM sleep. They also demonstrated that sleep spindles are instrumental to the consolidation process although its effect relies on a complex interaction between multiple frequency bands, including delta, theta and high-beta, both locally and inter-regionally. Overall, this thesis underlines the significance of NREM2 sleep spindles’ contribution to motor sequence consolidation. Importantly, building on decades of work, it lays the groundwork for studying the role of sleep spindles in memory consolidation within their temporal, topographical and frequential context

Physiognomic Map of Natural Vegetation

International audienc

Validating the theoretical bases of sleep reactivation during sharp‐wave ripples and their association with emotional valence

International audienc

CARHAB – Q2 : appui méthodologique à la cartographie des végétations naturelles et semi-naturelles des milieux ouverts de basse altitude

Suite au comité de pilotage de la convention DEB-Irstea 2013-2015 du 04 juillet 2013, ce document a pour objectif de faire le bilan des actions menées par l’UMR TETIS pour le projet Carhab depuis 2012 et jusqu’au 30 juillet 2013

Cartographie des habitats naturels et semi-naturels dans le paysages agricoles français

International audienceThe ‘Multi-scale Service for Monitoring Natura 2000 Habitats of European Community Interest (MS.MONINA)’ project is designed to develop new Earth Observation (EO)–based services for the cost-effective collection of information at different scales across the Natura 2000 network and beyond. The project’s design is unique in this sense as it integrates mapping approaches from the local to regional to European levels and addresses the reporting, monitoring and management needs of stakeholders at three scales: the individual local site, the Member State, and the EU. In this context, the National Research Institute of Science and Technology for Environment and Agriculture (Irstea) is developing a methodological framework for mapping of natural and semi-natural vegetation types across the French agricultural landscapes at a scale of 1/25000 using EO data. The service, under development, is tailored to lowland vegetation in open areas and is easily transferable to the different biogeographical regions characterizing the continental French territory (Continental, Atlantic, Mediterranean and Alpine)

Cartographie physionomique de la végétation naturelle

International audienceThis chapter describes the method that is based on works developed in the framework of a national project financed by the Ministry of the Environment, Energy and the Sea. The physiognomic map of natural vegetation provides a clear and homogeneous spatial framework to the field operators, even before deploying field teams. Natural vegetation is much more spectrally stable over time than crop vegetation. A time series throughout the vegetative period is used to discriminate between natural vegetation. The classification of vegetation densities, that is to say the level of opening of the media (herbaceous, open woody, dense woody), is based on texture data from the very high spatial resolution (VHSR) image. The treatments in the vegetation mapping method use the basic functionalities of the quantum geographic information system (QGIS) software as well as the integrated image processing library Orfeo Toolbox (OTB), developed by CNES

Intra-Ocular Pressure Response to Dexamethasone Implant Injections in Patients with a History of Filtering Surgery: The TRABEX Study

Patients with both macular edemas, of various etiologies such as diabetes and glaucoma, may suffer serious loss of vision if either disease goes untreated. Where no effective alternative therapies are available, dexamethasone implant (DEX-I) injections may be the only choice of treatment, despite the risk of a possible increase in intraocular pressure (IOP) when using steroids. Although many studies have reported on IOP evolution in eyes treated with DEX-I, little is known specifically about eyes with a history of filtering surgery. The aim of this observational series was to evaluate the IOP response following DEX-I injection in eyes presenting conventional filtering surgeries or microinvasive glaucoma surgeries (MIGS). Twenty-five eyes were included in this study. A total of 64% of the eyes did not experience OHT during follow-up. Additional IOP-lowering therapy was needed for 32% of eyes, and 20% of eyes (all showing bleb fibrosis) required further filtering surgery: 50% of eyes in the MIGS group and 10.5% of eyes in the conventional filtering surgery group. A significant positive correlation was found between IOP at baseline and the maximum IOP throughout follow-ups after DEX-I (r = 0.45, p = 0.02). In conclusion, if DEX-I is used when there are no alternative therapies for treating macular edema, IOP in eyes with a history of filtering surgery is generally manageable. Those eyes which previously underwent conventional therapy with effective blebs obtained better IOP control after DEX-I injections and mostly did not require any additional IOP-lowering therapy or surgery

Intra-Ocular Pressure Response to Dexamethasone Implant Injections in Patients with a History of Filtering Surgery: The TRABEX Study

International audiencePatients with both macular edemas, of various etiologies such as diabetes and glaucoma, may suffer serious loss of vision if either disease goes untreated. Where no effective alternative therapies are available, dexamethasone implant (DEX-I) injections may be the only choice of treatment, despite the risk of a possible increase in intraocular pressure (IOP) when using steroids. Although many studies have reported on IOP evolution in eyes treated with DEX-I, little is known specifically about eyes with a history of filtering surgery. The aim of this observational series was to evaluate the IOP response following DEX-I injection in eyes presenting conventional filtering surgeries or microinvasive glaucoma surgeries (MIGS). Twenty-five eyes were included in this study. A total of 64% of the eyes did not experience OHT during follow-up. Additional IOP-lowering therapy was needed for 32% of eyes, and 20% of eyes (all showing bleb fibrosis) required further filtering surgery: 50% of eyes in the MIGS group and 10.5% of eyes in the conventional filtering surgery group. A significant positive correlation was found between IOP at baseline and the maximum IOP throughout follow-ups after DEX-I (r = 0.45, p = 0.02). In conclusion, if DEX-I is used when there are no alternative therapies for treating macular edema, IOP in eyes with a history of filtering surgery is generally manageable. Those eyes which previously underwent conventional therapy with effective blebs obtained better IOP control after DEX-I injections and mostly did not require any additional IOP-lowering therapy or surgery

Improved sleep scoring in mice reveals human-like stages

International audienc

Behavioral and Sleep Data

Data are related to associated tab names in the manuscript and supplemental information. Groups are numbered as follow (1: Cond-NREM2; 2: Cond-REM; 3: NoCond)