Effects of spaced learning in the water maze on development of dentate granule cells generated in adult mice

TRINCHERO MF; KOEHL M; BECHAKRA M; DELAGE P; CHARRIER V; GROSJEAN N; LADEVEZE E; SCHINDER AF; ABROUS DN

Congreso; Adult neurogenesis; 2015

Dentate granule cells (GCs) are generated in the hippocampus throughout life. These adult-born neurons are required for spatial learning in the Morris water maze(MWM), and conversely, spatial learning itself regulates adult neurogenesis in complex ways. Indeed, spatial learning was found to shape the hippocampal network by regulating both the number and the dendritic development of newborn neurons in the rat brain. As genetically-engineered mice have become vital tools to approach the interactions between spatial learning and neurogenesis, we explored here whether the same modulatory effects exist in mice. New GCs were tagged using thymidine analogs or a GFP-expressing retrovirus. Animals were exposed to a reference memory protocol for 10 to 14 days spaced training at different times after newborn cells labeling. Cell proliferation, cell survival, cell death, neuronal phenotype and dendritic and spine development were examined using immunohistochemistry. Surprisingly,spatial learning did not modify any of the parameters under scrutiny including cell number and dendritic morphology. These results suggest that although new GCs are required in mice for spatial learning in the MWM, they are, at least for the developmental intervals analyzed here, refractory to behavioral stimuli generated in the course oflearning in the MWM.