Neuron to Astrocyte Communication via Cannabinoid Receptors Is Necessary for Sustained Epileptiform Activity in Rat Hippocampus

Astrocytes are integral functional components of synapses, regulating transmission and plasticity. They have also been implicated in the pathogenesis of epilepsy, although their precise roles have not been comprehensively characterized. Astrocytes integrate activity from neighboring synapses by responding to neuronally released neurotransmitters such as glutamate and ATP. Strong activation of astrocytes mediated by these neurotransmitters can promote seizure-like activity by initiating a positive feedback loop that induces excessive neuronal discharge. Recent work has demonstrated that astrocytes express cannabinoid 1 (CB1) receptors, which are sensitive to endocannabinoids released by nearby pyramidal cells. In this study, we tested whether this mechanism also contributes to epileptiform activity. In a model of 4-aminopyridine induced epileptic-like activity in hippocampal slice cultures, we show that pharmacological blockade of astrocyte CB1 receptors did not modify the initiation, but significantly reduced the maintenance of epileptiform discharge. When communication in astrocytic networks was disrupted by chelating astrocytic calcium, this CB1 receptor-mediated modulation of epileptiform activity was no longer observed. Thus, endocannabinoid signaling from neurons to astrocytes represents an additional significant factor in the maintenance of epileptiform activity in the hippocampus

The French Company of the Union: The French Attempt at Settlement in Eastern Maine, 1791-1796

Abstract not availabl

Au nom de la relation : Le cas des hymnes nationaux

Considérant la chanson comme un acte de communication (Lasswell 1948), l’objectif de cet article est d’examiner, de façon qualitative et inductive, le contenu religieux et non religieux ainsi que le contexte relationnel qui sous-tend les paroles des hymnes nationaux de 195 pays. À cet effet, nos résultats indiquent que la religion est mentionnée dans deux tiers des paroles des hymnes nationaux du monde. De plus, quatre types de relations semblent être présents au sein de celles-ci, soit des relations intragroupes, intergroupes et parasociales (une avec le pays et l’autre avec une entité religieuse). Finalement, nos analyses qualitatives permettent de préciser que les deux relations parasociales se déclinent comme reflétant une relation asymétrique complémentaire. Nous discutons ces résultats à la lumière de l’idée que l’identité se construit d’une manière relationnelle.Considering that a song can be construed as a communication act (Lasswell 1948), we examined, both qualitatively and inductively, the religious content of lyrics as well as the relational context underlying them within 195 national anthems. In line with this goal, our results indicate that religion is present in the lyrics of two thirds of the world’s national anthems. Our results also demonstrate that four types of relations underlie the content of lyrics namely intragroup and intergroup relations as well as two parasocial relations (one with country and the other with a religious entity). Finally, our qualitative analyses show that both parasocial interactions can be described as asymmetric yet complementary in nature. Results are discussed in line with the idea that identity is constructed in a relational manner