LTP inhibits LTD in the hippocampus via regulation of GSK3beta.: A role for GSK3beta in synaptic plasticity

International audienceGlycogen synthase kinase-3 (GSK3) has been implicated in major neurological disorders, but its role in normal neuronal function is largely unknown. Here we show that GSK3beta mediates an interaction between two major forms of synaptic plasticity in the brain, N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP) and NMDA receptor-dependent long-term depression (LTD). In rat hippocampal slices, GSK3beta inhibitors block the induction of LTD. Furthermore, the activity of GSK3beta is enhanced during LTD via activation of PP1. Conversely, following the induction of LTP, there is inhibition of GSK3beta activity. This regulation of GSK3beta during LTP involves activation of NMDA receptors and the PI3K-Akt pathway and disrupts the ability of synapses to undergo LTD for up to 1 hr. We conclude that the regulation of GSK3beta activity provides a powerful mechanism to preserve information encoded during LTP from erasure by subsequent LTD, perhaps thereby permitting the initial consolidation of learnt information

Museus Históricos na França: entre a reflexão histórica e a identidade nacional

Historical museums are a current subject in today's academic scenery in France. Two conferences on historical museums which took place by the end of 1996, as well as the reopening of the historical galleries at Versailles Museum early in 1997 show a growing interest in this sort of museum. This article reports the development of museums in France, since the early form of the Museum 01 French monuments, during the French Revolution until the publication, in september 1996, of a Guide to museums and historical collections in France. The A. tries to make clear the changes experienced by these institutions since last century, and to sum up the main arguments around the theme which, alter ali, goes beyond the French and European contexts.1996, de dois colóquios nacionais problematizando os museus desse gênero, bem como a discussão sobre a reabertura das galerias históricas de Versalhes, no início de 1997, demonstram um interesse crescente pela instituição. Este artigo traça um histórico dos museus de história na França, desde sua matriz inicial, delineada no ilfllsée des monllments jrançais durante a Revolução Francesa, até a publicação do Guide des musées et collections d'histoire en France, lançado em setembro de 1996. Através deste percurso, procura-se explicitar as inflexões sofridas pela instituição, desde o século XIX até recentemente, buscando, em especial, situar o conjunto de questionamentos que giram ao redor deste tema que, de resto, ultrapassa o contexto francês e europeu