Shank2 Mutant Mice Display Hyperactivity Insensitive to Methylphenidate and Reduced Flexibility in Social Motivation, but Normal Social Recognition

Mouse models of autism can be used to study evolutionarily conserved mechanisms underlying behavioral abnormalities in social communication and repetitive behaviors. SHANK genes code for synaptic scaffolding proteins at excitatory synapses and mutations in all SHANK genes have been associated with autism. Here, we present three behavioral aspects of the mutant mice deleted for exon 16 in Shank2. First, we treated Shank2 mutant mice with methylphenidate to rescue the hyperactivity. Our failure to do so suggests that the hyperactivity displayed by Shank2 mutant mice is not related to the one displayed by the typical mouse models of hyperactivity, and might be more closely related to manic-like behaviors. Second, by testing the effect of group housing and social isolation on social interest, we highlighted that Shank2 mutant mice lack the typical flexibility to modulate social interest, in comparison with wild-type littermates. Finally, we established a new protocol to test for social recognition in a social context. We used this protocol to show that Shank2 mutant mice were able to discriminate familiar and unknown conspecifics in free interactions. Altogether, these studies shed some light on specific aspects of the behavioral defects displayed by the Shank2 mouse model. Such information could be used to orient therapeutic strategies and to design more specific tests to characterize the complex behavior of mouse models of autism

Trisomy for Synaptojanin1 in Down syndrome is functionally linked to the enlargement of early endosomes

Enlarged early endosomes have been observed in neurons and fibroblasts in Down syndrome (DS). These endosome abnormalities have been implicated in the early development of Alzheimer's disease (AD) pathology in these subjects. Here, we show the presence of enlarged endosomes in blood mononuclear cells and lymphoblastoid cell lines (LCLs) from individuals with DS using immunofluorescence and confocal microscopy. Genotype-phenotype correlations in LCLs carrying partial trisomies 21 revealed that triplication of a 2.56 Mb locus in 21q22.11 is associated with the endosomal abnormalities. This locus contains the gene encoding the phosphoinositide phosphatase synaptojanin 1 (SYNJ1), a key regulator of the signalling phospholipid phosphatidylinositol-4,5-biphosphate that has been shown to regulate clathrin-mediated endocytosis. We found that SYNJ1 transcripts are increased in LCLs from individuals with DS and that overexpression of SYNJ1 in a neuroblastoma cell line as well as in transgenic mice leads to enlarged endosomes. Moreover, the proportion of enlarged endosomes in fibroblasts from an individual with DS was reduced after silencing SYNJ1 expression with RNA interference. In LCLs carrying amyloid precursor protein (APP) microduplications causing autosomal dominant early-onset AD, enlarged endosomes were absent, suggesting that APP overexpression alone is not involved in the modification of early endosomes in this cell type. These findings provide new insights into the contribution of SYNJ1 overexpression to the endosomal changes observed in DS and suggest an attractive new target for rescuing endocytic dysfunction and lipid metabolism in DS and in A

Objective comparison of particle tracking methods

Particle tracking is of key importance for quantitative analysis of intracellular dynamic processes from time-lapse microscopy image data. Because manually detecting and following large numbers of individual particles is not feasible, automated computational methods have been developed for these tasks by many groups. Aiming to perform an objective comparison of methods, we gathered the community and organized an open competition in which participating teams applied their own methods independently to a commonly defined data set including diverse scenarios. Performance was assessed using commonly defined measures. Although no single method performed best across all scenarios, the results revealed clear differences between the various approaches, leading to notable practical conclusions for users and developers

Cellular and Behavioral Effects of Cranial Irradiation of the Subventricular Zone in Adult Mice

Background: In mammals, new neurons are added to the olfactory bulb (OB) throughout life. Most of these new neurons, granule and periglomerular cells originate from the subventricular zone (SVZ) lining the lateral ventricles and migrate via the rostral migratory stream toward the OB. Thousands of new neurons appear each day, but the function of this ongoing neurogenesis remains unclear. Methodology/Principal Findings: In this study, we irradiated adult mice to impair constitutive OB neurogenesis, and explored the functional impacts of this irradiation on the sense of smell. We found that focal irradiation of the SVZ greatly decreased the rate of production of new OB neurons, leaving other brain areas intact. This effect persisted for up to seven months after exposure to 15 Gray. Despite this robust impairment, the thresholds for detecting pure odorant molecules and short-term olfactory memory were not affected by irradiation. Similarly, the ability to distinguish between odorant molecules and the odorant-guided social behavior of irradiated mice were not affected by the decrease in the number of new neurons. Only long-term olfactory memory was found to be sensitive to SVZ irradiation. Conclusion/Significance: These findings suggest that the continuous production of adult-generated neurons is involved i

Design of an assistant robot for serverly disabled people

Les travaux présentés dans ce mémoire traitent du développement d'une assistance robotisée comportant un bras préhenseur (Manus®) monté sur un porteur mobile capable de suivre de façon automatique le fauteuil roulant du patient afin de mettre à la disposition de l'utilisateur le bras Manus®. La première partie de ces travaux concerne la création d'un algorithme permettant la modélisation de capteurs catadioptriques omnidirectionnels particuliers. Ils répondent à des contraintes prédéfinies permettant d'observer différents éléments de l'environnement sans déformations radiales. Dans un second temps, nous exposons deux méthodes de suivi automatique de fauteuil roulant à l'aide des seuls capteurs de vision omnidirectionnelle stéréoscopique. La méthode mise en application dans le projet permet d'effectuer un suivi d'objet suivant une méthode probabiliste basée sur le MeanShift et le CAMShift. Dans ce mémoire, nous adaptons le CAMShift de façon à travailler directement sur les images omnidirectionnelles afin d'obtenir une méthode rapide baptisée OmniCAMShift. Cette méthode comprend également une initialisation simple par soustraction d'image, prenant en compte les ombres et les sur illuminations. Le troisième point concerne l'ensemble de la navigation. Nous y traitons la cartographie, apportant ici une nouvelle méthode d'appariement robuste d'amers utilisant des capteurs omnidirectionnels stéréoscopiques. L'exploitation de ces appariements permet de construire une grille d'occupation absolue de l'environnement, et d'inclure des procédures d'évitement d'obstacle et de passage de porte automatique. Ce mémoire ayant pour caractéristique d'être fortement appliqué, une dernière partie expose l'ensemble des résultats et travaux d'ergonomie dans le cadre d'interactions homme machine liés à l'utilisation de cette assistance.The work presented in this memory deals with the development of an aid for disabled people. This aid is the bundle of a Manus arm and a mobile robot, which is able to follow automatically the user's wheelchair. When the user wishes to use the Manus®, the mobile robot comes in front of the wheelchair and its occupant can use the Manus® arm. The first part of this work is the creation of an algorithm able to generate particular kind of omnidirectional catadioptric sensors. Those sensors allow to observe different parts of the environment without any radial deformation. In the second point, we explain two methods of automatic following of the wheelchair thanks to the sole stereoscopic omnidirectionals vision sensors. The method used in the project allows the tracking of an object using a probabilistic method based on the MeanShift and the CAMShift. In this work, we adapt the CAMShift in order to work directly on the omnidirectional images in order to get a method that we named OmniCAMShift. This method also embeds a simple initialisation of the model by subtracting images, taking into account shadows and highlights. The third point concerns the whole navigation. We deal with map generation, and we expose a new way to match the natural beacon using stereoscopic omnidirectional sensors. The use of those results enables to build an absolute occupation grid of the environment. Then we include the avoiding of obstacles and going through doors functionalities. This work has the particularity of being highly practical. A last part consequently shows the whole results and ergonomic work in the field of human-computer interface linked to the use of this aid for disabled people.AMIENS-BU Sciences (800212103) / SudocSudocFrancePolandFRP

Spontaneous social communication in laboratory mice - placing ultrasonic vocalizations in their behavioral context

Posté le 23 juillet 2020 sur BioRxivIn their natural habitat, mice interact and communicate to regulate major functions, such as reproduction, group coordination, and protection. Nevertheless, little is currently known about their spontaneous emission of ultrasonic vocalizations (USVs), despite their broad use as a phenotypic marker in mouse models of neuropsychiatric disorders. Here, we investigated mouse spontaneous communication by coupling automatic recording, segmentation, and analysis of USVs to the tracking of complex behaviors. We continuously recorded undisturbed same-sex pairs of C57BL/6J males and females at 5 weeks and 3 and 7 months of age over three days. Males emitted only a few short USVs, mainly when isolated from their conspecific, whereas females emitted a high number of USVs, especially when engaged in intense dynamic social interactions. The context-specific use of call types and acoustic variations emerged with increasing age. The emission of USVs also reflected a high level of excitement in social interactions. Finally, mice lacking Shank3, a synaptic protein associated with autism, displayed atypical USV usage and acoustic structure, which did not appear in classical protocols, highlighting the importance of studying spontaneous communication. The methods are freely available for the research community ( https://usv.pasteur.cloud )

Stress-induced brain activation: buffering role of social behavior and neuronal nicotinic receptors

International audienceSocial behavior and stress responses both rely on activity in the prefrontal cortex (PFC) and amygdala. We previously reported that acute stress exposure impoverishes social repertoire and triggers behavioral rigidity, and that both effects are modulated by β2-containing nicotinic receptors. We, therefore, hypothesized that the activity of brain regions associated with the integration of social cues will be modulated by stress exposure. We mapped the expression of c-fos protein in all subregions of the PFC and basolateral (BLA) and central (Ce) areas of the amygdala in C57BL/6J (B6) and β2-/- mice. We show altered brain activity and differences in functional connectivity between the two genotypes after stress: the PFC and BLA were hyperactivated in B6 and hypo-activated in β2-/- mice, showing that the impact of stress on brain activity and functional organization depends on the nicotinic system. We also show that the effects of the opportunity to explore a novel environment or interact socially after acute stress depended on genotype: exploration induced only marginal PFC activation in both genotypes relative to stress alone, excluding a major role for β2 receptors in this process. However, social interaction following stress only activated the rostral and caudolateral areas of the PFC in B6 mice, while it induced a kindling of activation in all PFC and amygdalar areas in β2-/- mice. These results indicate that acute stress triggers important PFC-amygdala plasticity, social interaction has a buffering role during stress-induced brain activation, and β2 receptors contribute to the effects of social interaction under stress

Deep learning-based system for real-time behavior recognition and closed-loop control of behavioral mazes using depth sensing

Robust quantification of animal behavior is fundamental in experimental neuroscience research. Systems providing automated behavioral assessment are an important alternative to manual measurements avoiding problems such as human bias, low reproducibility and high cost. Integrating these tools with closed-loop control systems creates conditions to correlate environment and behavioral expressions effectively, and ultimately explain the neural foundations of behavior. We present an integrated solution for automated behavioral analysis of rodents using deep learning networks on video streams acquired from a depth-sensing camera. The use of depth sensors has notable advantages: tracking/classification performance is improved and independent of animals’ coat color, and videos can be recorded in dark conditions without affecting animals’ natural behavior. Convolutional and recurrent layers were combined in deep network architectures, and both spatial and temporal representations were successfully learned for a 4- classes behavior classification task (standstill, walking, rearing and grooming). Integration with Arduino microcontrollers creates an easy-to-use control platform providing low-latency feedback signals based on the deep learning automatic classification of animal behavior. The complete system, combining depth-sensor camera, computer, and Arduino microcontroller, allows simple mapping of input-output control signals using the animal’s current behavior and position. For example, a feeder can be controlled not by pressing a lever but by the animal behavior itself. An integrated graphical user interface completes a user-friendly and cost-effective solution for animal tracking and behavior classification. This open-software/open-hardware platform can boost the development of customized protocols for automated behavioral research, and support ever more sophisticated, reliable and reproducible behavioral neuroscience experiments

mouseTube – a database to collaboratively unravel mouse ultrasonic communication [version 1; referees: 2 approved]

Ultrasonic vocalisation is a broadly used proxy to evaluate social communication in mouse models of neuropsychiatric disorders. The efficacy and robustness of testing these models suffer from limited knowledge of the structure and functions of these vocalisations as well as of the way to analyse the data. We created mouseTube, an open database with a web interface, to facilitate sharing and comparison of ultrasonic vocalisations data and metadata attached to a recording file. Metadata describe 1) the acquisition procedure, e.g., hardware, software, sampling frequency, bit depth; 2) the biological protocol used to elicit ultrasonic vocalisations; 3) the characteristics of the individual emitting ultrasonic vocalisations (e.g., strain, sex, age). To promote open science and enable reproducibility, data are made freely available. The website provides searching functions to facilitate the retrieval of recording files of interest. It is designed to enable comparisons of ultrasonic vocalisation emission between strains, protocols or laboratories, as well as to test different analysis algorithms and to search for protocols established to elicit mouse ultrasonic vocalisations. Over the long term, users will be able to download and compare different analysis results for each data file. Such application will boost the knowledge on mouse ultrasonic communication and stimulate sharing and comparison of automatic analysis methods to refine phenotyping techniques in mouse models of neuropsychiatric disorders

LMT USV Toolbox, a Novel Methodological Approach to Place Mouse Ultrasonic Vocalizations in Their Behavioral Contexts—A Study in Female and Male C57BL/6J Mice and in Shank3 Mutant Females

International audienceUltrasonic vocalizations (USVs) are used as a phenotypic marker in mouse models of neuropsychiatric disorders. Nevertheless, current methodologies still require time-consuming manual input or sound recordings clean of any background noise. We developed a method to overcome these two restraints to boost knowledge on mouse USVs. The methods are freely available and the USV analysis runs online at https://usv.pasteur.cloud . As little is currently known about usage and structure of ultrasonic vocalizations during social interactions over the long-term and in unconstrained context, we investigated mouse spontaneous communication by coupling the analysis of USVs with automatic labeling of behaviors. We continuously recorded during 3 days undisturbed interactions of same-sex pairs of C57BL/6J sexually naive males and females at 5 weeks and 3 and 7 months of age. In same-sex interactions, we observed robust differences between males and females in the amount of USVs produced, in the acoustic structure and in the contexts of emission. The context-specific acoustic variations emerged with increasing age. The emission of USVs also reflected a high level of excitement during social interactions. We finally highlighted the importance of studying long-term spontaneous communication by investigating female mice lacking Shank3 , a synaptic protein associated with autism. While the previous short-time constrained investigations could not detect USV emission abnormalities, our analysis revealed robust differences in the usage and structure of the USVs emitted by mutant mice compared to wild-type female pairs