Wednesday, March 14, 2007

Paradoxical influence of hippocampal neurogenesis on working memory

Michael D. Saxe, Gaël Malleret, Svetlana Vronskaya, Indira Mendez, A. Denise Garcia, Michael V. Sofroniew, Eric R. Kandel, and René Hen
PNAS | March 13, 2007 | vol. 104 | no. 11 | 4642-4646

To explore the function of adult hippocampal neurogenesis, we ablated cell proliferation by using two independent and complementary methods: (i) a focal hippocampal irradiation and (ii) an inducible and reversible genetic elimination of neural progenitor cells. Previous studies using these methods found a weakening of contextual fear conditioning but no change in spatial reference memory, suggesting a supportive role for neurogenesis in some, but not all, hippocampal-dependent memory tasks. In the present study, we examined hippocampal-dependent and -independent working memory using different radial maze tasks. Surprisingly, ablating neurogenesis caused an improvement of hippocampal-dependent working memory when repetitive information was presented in a single day. These findings suggest that adult-born cells in the dentate gyrus have different, and in some cases, opposite roles in distinct types of memory.

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