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Advanced Techniques for Synapse Biology

Laurent Chiffoleau et le BIC

Bordeaux School of Neuroscience

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  • Séminaire - Karun Singh

    24 mars 2017 à 10:30 - Nouveau bâtiment Neurocampus

    How do Autism spectrum disorder (ASD) risk genes i...

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    27 mars 2017 à 09:00 - CGFB

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  • François Georges et al. dans Nature Communications

    10 mars 2017

    l'anxiété: un mécanisme de survie...

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  • Semaine du cerveau 2017 / Société des Neurosciences

    9 mars 2017

    conférences , visites de labo, ateliers...

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  • P-V Piazza et al. dans Neuron

    23 mars 2017

    expliquer la nature apparemment paradoxale de la f...

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Memories of Opiate Withdrawal Emotional States Correlate with Specific Gamma Oscillations in the Nucleus Accumbens.Memories of Opiate Withdrawal Emotional States Correlate with Specific Gamma Oscillations in the Nucleus Accumbens.
Affective memories associated with the negative emotional state experienced during opiate withdrawal are central in maintaining drug taking, seeking, and relapse. Nucleus accumbens (NAC) is a key structure for both acute withdrawal and withdrawal memories reactivation, but the NAC neuron coding properties underpinning the expression of these memories remain largely unknown. Here we aimed at deciphering the role of NAC neurons in the encoding and retrieval of opiate withdrawal memory. Chronic single neuron and local field potentials recordings were performed in morphine-dependent rats and placebo controls. Animals were subjected to an unbiased conditioned placed aversion protocol with one compartment (CS+) paired with naloxone-precipitated withdrawal, a second compartment with saline injection (CS-), and a third being neutral (no pairing). After conditioning, animals displayed a typical place aversion for CS+ and developed a preference for CS- characteristic of safety learning. We found that distinct NAC neurons code for CS+ or CS-. Both populations also displayed highly specific oscillatory dynamics, CS+ and CS- neurons, respectively, following 80 Hz (G80) and 60 Hz (G60) local field potential gamma rhythms. Finally, we found that the balance between G60 and G80 rhythms strongly correlated both with the ongoing behavior of the animal and the strength of the conditioning. We demonstrate here that the aversive and preferred environments are underpinned by distinct groups of NAC neurons as well as specific oscillatory dynamics. This suggest that G60/G80 interplay-established through the conditioning process-serves as a robust and versatile mechanism for a fine coding of the environment emotional weight.
Dejean C, Sitko M, Girardeau P, Bennabi A, Caillé S, Cador M, Boraud T, Le Moine C.
Neuropsychopharmacology. 2017 Jan 4

Neuroinflammation in Autism: Plausible Role of Maternal Inflammation, Dietary Omega 3, and Microbiota.Neuroinflammation in Autism: Plausible Role of Maternal Inflammation, Dietary Omega 3, and Microbiota.
Several genetic causes of autism spectrum disorder (ASD) have been identified. However, more recent work has highlighted that certain environmental exposures early in life may also account for some cases of autism. Environmental insults during pregnancy, such as infection or malnutrition, seem to dramatically impact brain development. Maternal viral or bacterial infections have been characterized as disruptors of brain shaping, even if their underlying mechanisms are not yet fully understood. Poor nutritional diversity, as well as nutrient deficiency, is strongly associated with neurodevelopmental disorders in children. For instance, imbalanced levels of essential fatty acids, and especially polyunsaturated fatty acids (PUFAs), are observed in patients with ASD and other neurodevelopmental disorders (e.g., attention deficit hyperactivity disorder (ADHD) and schizophrenia). Interestingly, PUFAs, and specifically n-3 PUFAs, are powerful immunomodulators that exert anti-inflammatory properties. These prenatal dietary and immunologic factors not only impact the fetal brain, but also affect the microbiota. Recent work suggests that the microbiota could be the missing link between environmental insults in prenatal life and future neurodevelopmental disorders. As both nutrition and inflammation can massively affect the microbiota, we discuss here how understanding the crosstalk between these three actors could provide a promising framework to better elucidate ASD etiology.
Madore C, Leyrolle Q, Lacabanne C, Benmamar-Badel A, Joffre C, Nadjar A, Layé S.
Neural Plast. 2016. Review.

Pregnenolone blocks cannabinoid-induced acute psychotic-like states in mice.Pregnenolone blocks cannabinoid-induced acute psychotic-like states in mice.
Cannabis-induced acute psychotic-like states (CIAPS) represent a growing health issue, but their underlying neurobiological mechanisms are poorly understood. The use of antipsychotics and benzodiazepines against CIAPS is limited by side effects and/or by their ability to tackle only certain aspects of psychosis. Thus, safer wide-spectrum treatments are currently needed. Although the blockade of cannabinoid type-1 receptor (CB1) had been suggested as a therapeutical means against CIAPS, the use of orthosteric CB1 receptor full antagonists is strongly limited by undesired side effects and low efficacy. The neurosteroid pregnenolone has been recently shown to act as a potent endogenous allosteric signal-specific inhibitor of CB1 receptors. Thus, we tested in mice the potential therapeutic use of pregnenolone against acute psychotic-like effects of Δ9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis. We found that pregnenolone blocks a wide spectrum of THC-induced endophenotypes typically associated with psychotic-like states, including impairments in cognitive functions, somatosensory gating and social interaction. In order to capture THC-induced positive psychotic-like symptoms (e.g. perceptual delusions), we adapted a behavioral paradigm based on associations between different sensory modalities and selective devaluation, allowing the measurement of mental sensory representations in mice. Acting at hippocampal CB1 receptors, THC impaired the correct processing of mental sensory representations (reality testing) in an antipsychotic- and pregnenolone-sensitive manner. Overall, this work reveals that signal-specific inhibitors mimicking pregnenolone effects can be considered as promising new therapeutic tools to treat CIAPS.
Busquets-Garcia A, Soria-Gómez E, Redon B, Mackenbach Y, Vallée M, Chaouloff F, Varilh M, Ferreira G, Piazza PV, Marsicano G.
Mol Psychiatry. 2017 Feb 21

Social harassment induces anxiety-like behaviour in crayfish.Social harassment induces anxiety-like behaviour in crayfish.
Social interactions leading to dominance hierarchies often elicit psychological disorders in mammals including harassment and anxiety. Here, we demonstrate that this sequence also occurs in an invertebrate, the crayfish Procambarus clarkii. When placed in the restricted space of an aquarium, crayfish dyads generally fight until one of the opponents suddenly escapes, thereafter clearly expressing a submissive behaviour. Nevertheless, the winner frequently keeps on displaying excessive aggressive acts, having deleterious consequences in losers and interpreted as harassment behaviour. We indeed observed that, contrary to winners, losers expressed anxiety-like behaviour (ALB) in correlation with the stress intensity they suffered during the harassment period mainly. Injections of an anxiolytic abolished ALB, confirming its homology with anxiety. A serotonin (5-HT) antagonist had the same effect, suggesting a role for 5-HT, whose brain concentrations increased much more in losers than in winners. Our findings suggest that the bases of harassment and of its anxiogenic consequences have emerged very early during evolution, and emphasize crayfish as an unexpected but potentially fruitful model for the study of these social disorders.
Bacqué-Cazenave J, Cattaert D, Delbecque JP, Fossat P.
Sci Rep. 2017 Jan 3

Spatial and Temporal Regulation of Receptor Endocytosis in Neuronal Dendrites Revealed by Imaging of Single Vesicle Formation.Spatial and Temporal Regulation of Receptor Endocytosis in Neuronal Dendrites Revealed by Imaging of Single Vesicle Formation.
Endocytosis in neuronal dendrites is known to play a critical role in synaptic transmission and plasticity such as long-term depression (LTD). However, the inability to detect endocytosis directly in living neurons has hampered studies of its dynamics and regulation. Here, we visualized the formation of individual endocytic vesicles containing pHluorin-tagged receptors with high temporal resolution in the dendrites of cultured hippocampal neurons. We show that transferrin receptors (TfRs) are constitutively internalized at optically static clathrin-coated structures. These structures are slightly enriched near synapses that represent preferential sites for the endocytosis of postsynaptic AMPA-type receptors (AMPARs), but not for non-synaptic TfRs. Moreover, the frequency of AMPAR endocytosis events increases after the induction of NMDAR-dependent chemical LTD, but the activity of perisynaptic endocytic zones is not differentially regulated. We conclude that endocytosis is a highly dynamic and stereotyped process that internalizes receptors in precisely localized endocytic zones.
Rosendale M, Jullié D, Choquet D, Perrais D.
Cell Rep. 2017 Feb 21

Superresolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity.Superresolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity.
Axons convey information to nearby and distant cells, and the time it takes for action potentials (APs) to reach their targets governs the timing of information transfer in neural circuits. In the unmyelinated axons of hippocampus, the conduction speed of APs depends crucially on axon diameters, which vary widely. However, it is not known whether axon diameters are dynamic and regulated by activity-dependent mechanisms. Using time-lapse superresolution microscopy in brain slices, we report that axons grow wider after high-frequency AP firing: synaptic boutons undergo a rapid enlargement, which is mostly transient, whereas axon shafts show a more delayed and progressive increase in diameter. Simulations of AP propagation incorporating these morphological dynamics predicted bidirectional effects on AP conduction speed. The predictions were confirmed by electrophysiological experiments, revealing a phase of slowed down AP conduction, which is linked to the transient enlargement of the synaptic boutons, followed by a sustained increase in conduction speed that accompanies the axon shaft widening induced by high-frequency AP firing. Taken together, our study outlines a morphological plasticity mechanism for dynamically fine-tuning AP conduction velocity, which potentially has wide implications for the temporal transfer of information in the brain.
Chéreau R, Saraceno GE, Angibaud J, Cattaert D, Nägerl UV.
Proc Natl Acad Sci U S A. 2017 Feb 7


La recherche, "grande absente du débat" de la présidentielle

22 mars 2017

...hélas, à quelques exceptions près, les responsables ­politiques sont éloignés du monde de la recherche et de l’enseignement supérieur. Ils ­semblen...► Lire la suite

L'AST: nous soutenons, valorisons et brevetons vos recherches...

6 mars 2017

...votre résultat de recherche pourra faire l’objet d’un dépôt d’une demande de brevet ou encore d’un programme de maturation soutenu financièrement p...► Lire la suite

Mois de Mars : c'est le NEURODON !

13 mars 2017

La campagne de collecte du Neurodon 2017 aura lieu dans les enseignes de nos partenaires, et notamment dans les hypermarchés Carrefour et Carrefour Ma...► Lire la suite


Post-doc positions open 
Available post-doctoral position in synaptic physiology (Choquet Lab)
We are seeking to recruit as soon as possible a post-doctoral fellow expert in slice electrophysiology and imaging to study AMPA receptor trafficking and synaptic function with innovative molecular and imaging approaches.... 

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en ligne le 19 sept 2016 ....Recherchons: Chef de projet du centre  d’excellence sur  les maladies neurodégénératives CHU de Bordeaux Hôpital Pellegrin - Institut des Maladies Neurodégénératives

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SynDegen is currently able to offer 12 PhD student positions in the SynDegen ITN. Recrutons 2 thésards sur Bordeaux. Deadline pour les applications le 31 Janvier 2017…

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 Faculty of Health at Aarhus University, Call for applications........Proposition Poste MCU Poitiers : Le candidat travaillera dans l’équipe NeuroDéveloppement- NeuroAdaptation-NeuroDégénérescence au sein de l’UMR_S 1084 Inserm (LNEC)....



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