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Disruption of hippocampal CA3 network: effects on episodic-like memory processing in C57BL/6J mice

Authors

  • Stéphanie Daumas,

    1. Centre de Recherches sur la Cognition Animale, CNRS UMR 5169, Bât 4R3 b3, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
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  • Hélène Halley,

    1. Centre de Recherches sur la Cognition Animale, CNRS UMR 5169, Bât 4R3 b3, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
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  • Jean-Michel Lassalle

    1. Centre de Recherches sur la Cognition Animale, CNRS UMR 5169, Bât 4R3 b3, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
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Dr Stéphanie Daumas, as above.
E-mail: sdaumas@cict.fr

Abstract

Lesion studies have demonstrated the prominent role of the hippocampus in spatial and contextual learning. To better understand how contextual information is processed in the CA3 region during learning, we focused on the CA3 autoassociative network hypothesis. We took advantage of a particularity of the mossy fibre (MF) synapses, i.e. their high zinc concentration, to reversibly disrupt the afferent MF pathway by microinfusions of an intracellular (DEDTC) or an extracellular (CaEDTA) zinc chelator into the CA3 area of the dorsal hippocampus of mice. Disruption of the CA3 network significantly impaired the acquisition and the consolidation of contextual fear conditioning, whereas contextual retrieval was unaffected. These results also suggest a heterogeneity between the cognitive processes underlying spatial and contextual memory that might be linked to the specific involvement of free zinc in contextual information processing.

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