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Synaptogenesis of mossy fibers induced by spatial water maze overtraining
Author(s) -
RamírezAmaya Víctor,
Escobar Martha L.,
Chao Vincent,
BermúdezRattoni Federico
Publication year - 1999
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/(sici)1098-1063(1999)9:6<631::aid-hipo3>3.0.co;2-3
Subject(s) - mossy fiber (hippocampus) , neuroscience , synaptogenesis , hippocampus , overtraining , water maze , synaptic plasticity , hippocampal formation , long term potentiation , morris water navigation task , psychology , chemistry , dentate gyrus , medicine , biochemistry , receptor , athletes , physical therapy
Synaptic plasticity has been proposed as a mechanism underlying learning and memory. Synaptic reorganization of hippocampal mossy fibers has been observed after experimentally induced epilepsy, and after brief high‐frequency activation inducing long‐term potentiation. Furthermore, it has been suggested that synaptic changes in the hippocampus may occur after spatial learning. In this study, by using a zinc‐detecting histologic technique (Timm), we demonstrate a significant increase of mossy fiber terminals in the CA3 stratum oriens region induced by training rats during 3 days in a spatial Morris water maze. In contrast, animals trained for only 1 day and animals that were just allowed to swim or were overtrained in a stress‐motivated inhibitory avoidance task did not show increments of mossy fiber terminals in the stratum oriens. Electron microscopy confirmed that synaptic density of mossy fiber terminals in the stratum oriens increases significantly in water maze overtrained animals compared with the swimming control animals. Taken together, these results suggest that overtraining in a spatial learning task induces mossy fiber synaptogenesis that could be involved in the mechanisms underlying long‐term memory storage. Hippocampus 1999;9:631–636. © 1999 Wiley‐Liss, Inc.