418 research outputs found
COACHES Cooperative Autonomous Robots in Complex and Human Populated Environments
Public spaces in large cities are increasingly becoming complex and unwelcoming environments. Public spaces progressively become more hostile and unpleasant to use because of the overcrowding and complex information in signboards. It is in the interest of cities to make their public spaces easier to use, friendlier to visitors and safer to increasing elderly population and to citizens with disabilities. Meanwhile, we observe, in the last decade a tremendous progress in the development of robots in dynamic, complex and uncertain environments. The new challenge for the near future is to deploy a network of robots in public spaces to accomplish services that can help humans. Inspired by the aforementioned challenges, COACHES project addresses fundamental issues related to the design of a robust system of self-directed autonomous robots with high-level skills of environment modelling and scene understanding, distributed autonomous decision-making, short-term interacting with humans and robust and safe navigation in overcrowding spaces. To this end, COACHES will provide an integrated solution to new challenges on: (1) a knowledge-based representation of the environment, (2) human activities and needs estimation using Markov and Bayesian techniques, (3) distributed decision-making under uncertainty to collectively plan activities of assistance, guidance and delivery tasks using Decentralized Partially Observable Markov Decision Processes with efficient algorithms to improve their scalability and (4) a multi-modal and short-term human-robot interaction to exchange information and requests. COACHES project will provide a modular architecture to be integrated in real robots. We deploy COACHES at Caen city in a mall called “Rive de l’orne”. COACHES is a cooperative system consisting of ?xed cameras and the mobile robots. The ?xed cameras can do object detection, tracking and abnormal events detection (objects or behaviour). The robots combine these information with the ones perceived via their own sensor, to provide information through its multi-modal interface, guide people to their destinations, show tramway stations and transport goods for elderly people, etc.... The COACHES robots will use different modalities (speech and displayed information) to interact with the mall visitors, shopkeepers and mall managers. The project has enlisted an important an end-user (Caen la mer) providing the scenarios where the COACHES robots and systems will be deployed, and gather together universities with complementary competences from cognitive systems (SU), robust image/video processing (VUB, UNICAEN), and semantic scene analysis and understanding (VUB), Collective decision-making using decentralized partially observable Markov Decision Processes and multi-agent planning (UNICAEN, Sapienza), multi-modal and short-term human-robot interaction (Sapienza, UNICAEN
Etude du frittage réactif dans le système Al2O3-AIN-MgO. Application à l'élaboration d'une céramique spinelle oxynitrurée transparente
Pas de résumé en anglaisLa céramique spinelle oxynitrure d'aluminium et de magnésium est obtenue transparente dans le visible et l'infra-rouge par frittage réactif d'un mélange de poudres d'alumine, nitrure d'aluminium et oxyde de magnésium. L'oxynitrure d'aluminium et de magnésium se forme par réaction en phase solide entre une structure spinelle hôte (aluminate de magnésium ou oxynitrure d'aluminium) et du nitrure d'aluminium ou de l'oxyde de magnésium. Son apparition est généralement effective au dessus de 1350 0c mais peut être observée a 1200c (par réaction oxyde de magnésium oxynitrure d'aluminium). La présence de nitrure d'aluminium induit le départ d'espèces gazeuses magnésium et azote par réaction avec l'oxyde de magnésium ou l'aluminate de magnésium. Ces départs affaiblissent les teneurs en azote et de magnésium de la solution solide et modifient la microstructure. Mais ce départ peut être limite en utilisant un environnement stabilisateur constitue d'oxyde de magnésium et de nitrure d'aluminium. La microstructure des matériaux est étroitement liée aux matières premières. Un caractère binodal est note lorsque la structure hôte spinelle aluminate de magnésium est présente au départ alors qu'une taille de grains fins et homogènes est observée si le spinelle hôte est forme in situ. Des recuits successifs en dessous de 1750c ne modifient que légèrement la taille des grains. Une post compression isostatique à chaud est nécessaire pour éliminer la fine porosité résiduelle et l'évolution microstructurale différé selon les matières premières, les conditions de pré-traitement par frittage sous charge et la température de post compression isostatique à chaud
Rôle(s) des motivations naturelles dans la prise décision (bases neurobiologiques et comportementales)
La prise de décision est un processus indispensable et vital pour les mammifères. Elle permet à l individu de s adapter aux changements qui s opèrent dans son environnement et résulte de l intégration d informations sensorielles, émotionnelles, motivationnelles et exécutives (qui peuvent être internes ou externes à l individu). Des études, à la fois chez le sujet humain (sujet sain, patients cérébrolésés ou atteints de pathologies psychiatriques), et sur les modèles animaux singe, rats ou souris, ont permis d identifier le cortex préfrontal comme acteur crucial dans ces processus exécutifs complexes. La mise en place au sein de notre laboratoire d un test d interaction sociale permettant de générer des prises de décision rapides et adaptées en présence d un congénère nouveau, nous a permis d étudier les bases neurobiologiques et comportementales sous-jacentes à la prise de décision et à la flexibilité comportementale. Il est connu que les rongeurs émettent des USVs dont le rôle et les mécanismes motivationnels et/ou émotionnels restent largement inconnus à ce jour. Mon travail de thèse repose principalement sur l identification des acteurs cérébraux de cette interaction sociale, et sur le rôle putatif des USVs. D autre part, je me suis employé à comprendre comment les motivations naturelles (telles que la nourriture, l exploration d objet ou de l environnement, et l interaction avec un congénère) sont intégrées au canevas de prise de décision et comment elles l influencent.Dans un premier temps, en utilisant des procédures d imagerie cellulaire basée sur l expression de gènes précoces (c-fos), et ce, à la fois chez des animaux contrôles et chez des animaux présentant des troubles des comportements sociaux (b2KO), nous avons pu mettre en évidence l implication différentielle de sous-parties du cortex préfrontal chez la souris. Par la suite, la mise en place d un logiciel spécifique d analyse, ainsi que la modulation de l état de motivation de l animal lors de la tâche d interaction sociale, nous a permis de mieux comprendre l établissement de comportements adaptés lors de l interaction sociale. Pour finir, en variant les contextes comportementaux, nous avons montré qu il existe une relation étroite entre état émotionnel et motivationnel de l animal et émission d USVs. Notamment, les USVs semblent porter une information spécifique lors de l interaction sociale qui reste encore largement à déterminer.Decision-making is one of the most essential process for mammals. It allows the individual to adapt to environmental changes by the integration of sensory, emotional, motivational and executive information. Numerous studies, in human subject (healthy or not), and on animal models like monkey, rats or mice, have allowed the identification of a major actor in these complex processes: the prefrontal cortex. In our laboratory, we set up a new test, called the social interaction task -SIT-, to generate quick and adapted decision-making in presence of a new congener. This task was used to dissect neural and behavioral bases underlying decision-making and behavioral flexibility during social interaction. It is well known now that rodents emit ultrasonic vocalizations -USVs-, of which roles and mechanisms (motivational or emotional) remain largely unknown. My work was devoted to the identification of brain structures that allow flexible social interactions, and to the unraveling of the putative role(s) of USVs during SIT. I also tried to understand how natural motivations (like social interaction, exploration, and food consumption) take part in the decision-making process.First, by using cellular imaging procedure based on the expression of immediate early genes (c-fos): we were able to highlight the differential involvement of sub-areas of the prefrontal cortex in mice. Subsequently, the development of a new specific software, and the ability to modulate the motivational state of the animal, enabled us to understand better the establishment of adapted behaviors during the SIT. Finally, by varying behavioral contexts, we found a tight relationship between emotional/motivational states and USVs emissions. Notably, USVs appear to carry specific information in social interaction, and this point largely remains to be determined.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF
La barre et la topologie lacanienne
Que la cure ne puisse se passer que dans une langue particulière (ce qu’on appelle : positive), même à jouer de la traduire, y fait garantie « qu’il n’y a pas de métalangage » selon ma formule. L’effet de langue ne s’y produit que du cristal linguistique. Son universalité n’est que la topologie retrouvée, de ce qu’un discours s’y déplace. L’accès topologique y étant même assez prégnant pour que la mythologie s’y réduise à l’extrême ». La psychanalyse a un savoir sur la langue, ce savoir sur l..
Hippocampal neural disinhibition causes attentional and memory deficits
Subconvulsive hippocampal neural disinhibition, that is reduced GABAergic inhibition, has been implicated in neuropsychiatric disorders characterized by attentional and memory deficits, including schizophrenia and age-related cognitive decline. Considering that neural disinhibition may disrupt both intra-hippocampal processing and processing in hippocampal projection sites, we hypothesized that hippocampal disinhibition disrupts hippocampus-dependent memory performance and, based on strong hippocampo-prefrontal connectivity, also prefrontal-dependent attention. In support of this hypothesis, we report that acute hippocampal disinhibition by microinfusion of the GABA-A receptor antagonist picrotoxin in rats impaired hippocampus-dependent everyday-type rapid place learning performance on the watermaze delayed-matching-to-place test and prefrontal-dependent attentional performance on the 5-choice-serial-reaction-time test, which does not normally require the hippocampus. For comparison, we also examined psychosis-related sensorimotor effects, using startle/prepulse inhibition (PPI) and locomotor testing. Hippocampal picrotoxin moderately increased locomotion and slightly reduced startle reactivity, without affecting PPI. In vivo electrophysiological recordings in the vicinity of the infusion site showed that picrotoxin mainly enhanced burst firing of hippocampal neurons. In conclusion, hippocampal neural disinhibition disrupts hippocampus-dependent memory performance and also manifests through deficits in not normally hippocampus-dependent attentional performance. These behavioral deficits may reflect a disrupted control of burst firing, which may disrupt hippocampal processing and cause aberrant drive to hippocampal projection sites
Characterization of social behavior in young and middle-aged ChAT-IRES-Cre mouse
The cholinergic system is an important modulator of brain processes. It contributes to the regulation of several cognitive functions and emotional states, hence altering behaviors. Previous works showed that cholinergic (nicotinic) receptors of the prefrontal cortex are needed for adapted social behaviors. However, these data were obtained in mutant mice that also present alterations of several neurotransmitter systems, in addition to the cholinergic system. ChAT-IRES-Cre mice, that express the Cre recombinase specifically in cholinergic neurons, are useful tools to investigate the role of the cholinergic circuits in behavior. However, their own behavioral phenotype has not yet been fully characterized, in particular social behavior. In addition, the consequences of aging on the cholinergic system of ChAT-IRES-Cre mice has never been studied, despite the fact that aging is known to compromise the cholinergic system efficiency. The aim of the current study was thus to characterize the social phenotype of ChAT-IRES-Cre mice both at young (2–3 months) and middle (10–11 months) ages. Our results reveal an alteration of the cholinergic system, evidenced by a decrease of ChAT, CHT and VAChT gene expression in the striatum of the mice, that was accompanied by mild social disturbances and a tendency towards anxiety. Aging decreased social dominance, without being amplified by the cholinergic alterations. Altogether, this study shows that ChAT-IRES-Cre mice are useful models for studying the cholinergic system‘s role in social behavior using appropriate modulating technics (optogenetic or DREADD). </p
Effects of dopamine D1 modulation of the anterior cingulate cortex in a fear conditioning procedure
The anterior cingulate cortex (AC) component of the medial prefrontal cortex (mPFC) has been implicated in attention and working memory as measured by trace conditioning. Since dopamine (DA) is a key modulator of mPFC function, the present study evaluated the role of DA receptor agents in rat AC, using trace fear conditioning. A conditioned stimulus (CS, noise) was followed by an unconditioned stimulus (US, shock) with or without a 10s trace interval interposed between these events in a between-subjects design. Conditioned suppression of drinking was assessed in response to presentation of the CS or an experimental background stimulus (flashing lights, previously presented for the duration of the conditioning session). The selective D1 agonist SKF81297 (0.05 µg/side) or D1 antagonist SCH23390 (0.5 µg/side) was administered by intra-cerebral microinfusion directly into AC. It was predicted that either of these manipulations should be sufficient to impair trace (but not delay) conditioning. Counter to expectation, there was no effect of DA D1 modulation on trace conditioning as measured by suppression to the noise CS. However, rats infused with SKF81297 acquired stronger conditioned suppression to the experimental background stimulus than those infused with SCH23390 or saline. Thus, the DA D1 agonist SKF81297 increased conditioned suppression to the contextual background light stimulus but was otherwise without effect on fear conditioning
Behavioral Sequence Analysis Reveals a Novel Role for ß2* Nicotinic Receptors in Exploration
Nicotinic acetylcholine receptors (nAChRs) are widely expressed throughout the
central nervous system and modulate neuronal function in most mammalian brain
structures. The contribution of defined nAChR subunits to a specific behavior is
thus difficult to assess. Mice deleted for ß2-containing nAChRs
(ß2−/−) have been shown to be hyperactive in an
open-field paradigm, without determining the origin of this hyperactivity. We
here develop a quantitative description of mouse behavior in the open field
based upon first order Markov and variable length Markov chain analysis focusing
on the time-organized sequence that behaviors are composed of. This description
reveals that this hyperactivity is the consequence of the absence of specific
inactive states or “stops”. These stops are associated with
a scanning of the environment in wild-type mice (WT), and they affect the way
that animals organize their sequence of behaviors when compared with stops
without scanning. They characterize a specific “decision
moment” that is reduced in ß2−/− mutant
mice, suggesting an important role of ß2-nAChRs in the strategy used
by animals to explore an environment and collect information in order to
organize their behavior. This integrated analysis of the displacement of an
animal in a simple environment offers new insights, specifically into the
contribution of nAChRs to higher brain functions and more generally into the
principles that organize sequences of behaviors in animals
Adult Male Mice Emit Context-Specific Ultrasonic Vocalizations That Are Modulated by Prior Isolation or Group Rearing Environment
Social interactions in mice are frequently analysed in genetically modified strains in order to get insight of disorders affecting social interactions such as autism spectrum disorders. Different types of social interactions have been described, mostly between females and pups, and between adult males and females. However, we recently showed that social interactions between adult males could also encompass cognitive and motivational features. During social interactions, rodents emit ultrasonic vocalizations (USVs), but it remains unknown if call types are differently used depending of the context and if they are correlated with motivational state. Here, we recorded the calls of adult C57BL/6J male mice in various behavioral conditions, such as social interaction, novelty exploration and restraint stress. We introduced a modulator for the motivational state by comparing males maintained in isolation and males maintained in groups before the experiments. Male mice uttered USVs in all social and non-social situations, and even in a stressful restraint context. They nevertheless emitted the most important number of calls with the largest diversity of call types in social interactions, particularly when showing a high motivation for social contact. For mice maintained in social isolation, the number of calls recorded was positively correlated with the duration of social contacts, and most calls were uttered during contacts between the two mice. This correlation was not observed in mice maintained in groups. These results open the way for a deeper understanding and characterization of acoustic signals associated with social interactions. They can also help evaluating the role of motivational states in the emission of acoustic signals
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