Aim of the work. Although evidence suggest that neurogenesis play a role in spatial learning, the effect of learning on cell proliferation remains unclear. The authors generated and tested the hypothesis that different phases of spatial learning measured in the Morris water maze have distinct actions on cell proliferation. In this task, two phases of learning can be distinguished: an early phase during which performance improves rapidly, and a late phase during which asymptotic levels of performance are reached. These two phases seem to involve different brain processes and consequently may differentially influence neurogenesis.
Results. The authors demonstrated that the late phase of learning has a multifaceted effect on neurogenesis depending on the birth date of new neurons. The number of newly born cells increased contingently with the late phase and a large proportion of these cells survived for at least 4 weeks and differentiated into neurons. In contrast, the late phase learning decreased the number of newly born cells produced during the early phase. This learning-induced decrease in the number of newly generated cells results most probably from the death of the cells. Strikingly, cell death and not proliferation was positively correlated with performance in the water-maze. Thus, rats with the lowest cell death were less able to acquire and use spatial information than those with the highest cell death.
Conclusion. The results reveal a complex modulation of learning on brain plasticity, which induces death and proliferation of different populations of cells. Most importantly, they introduce the notion that removing neurons from the adult brain can be an important process in learning and memory and a novel mechanism through which neurogenesis may influence normal and pathological behaviors.
Citation source: Molecular Psychiatry 2003 Volume 8, number 12, pages 974-982.
AUTHORS: MatŔ Daniel D÷br÷ssy*, Elodie Drapeau*, Catherine Aurousseau, Michel Le Moal, Pier Vincenzo Piazza, Djoher Nora Abrous * have equally contributed to the work
INSERM U259, University of Bordeaux, Domaine de Carreire, Bordeaux, France
For further information on this work, please contact Dr. Nora Abrous, INSERM U.588, Institut Franšois Magendie, Rue Camille Saint-SaŰns, 33077 Bordeaux Cedex, France. Tel: 33-5-57-57-36-86, Fax: 33-5-56-96-68-93, E-mail: firstname.lastname@example.org
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