Neuronal integration in the adult mouse olfactory bulb is a non-selective addition process

Jean-Claude Platel (1) , Alexandra Angelova (1) , Stéphane Bugeon (1) , Jenelle Wallace (2) , Thibault Ganay (1) , Ilona Chudotvorova (3) , Jean-Christophe Deloulme (4) , Christophe Béclin (1) , Marie-Catherine Tiveron (1) , Nathalie Coré (1) , Venkatesh N Murthy (2) , Harold Cremer (1)

1 IBDM - Institut de Biologie du Développement de Marseille
2 Harvard University
3 Epilepsie et ischémie cérébrale
4 Physiopathologie du Cytosquelette

Adult neurogenesis in the olfactory bulb (OB) is considered as a competition in which neurons scramble during a critical selection period for integration and survival. Moreover, newborn neurons are thought to replace pre-existing ones that die. Despite indirect evidence supporting this model, systematic in vivo observations are still scarce. We used two-photon in vivo imaging to study neuronal integration and survival. We show that loss of new neurons in the OB after arrival at terminal positions occurs only at low levels. Moreover, long-term observations showed that no substantial cell death occurred at later stages. Neuronal death was induced by standard doses of thymidine analogs, but disappeared when low doses were used. Finally, we demonstrate that the OB grows throughout life. This shows that neuronal selection during OB-neurogenesis does not occur after neurons reached stable positions. Moreover, this suggests that OB neurogenesis does not represent neuronal turnover but lifelong neuronal addition.

Domaines: Neurobiologie

Jean-Claude Platel, Alexandra Angelova, Stéphane Bugeon, Jenelle Wallace, Thibault Ganay, et al.. Neuronal integration in the adult mouse olfactory bulb is a non-selective addition process. eLife, 2019, 8, pp.e44830. ⟨10.7554/eLife.44830⟩. ⟨hal-02382367⟩