In socially isolated animals one to two neurons were produced for every NSC in the total dentate exhibiting a linear stoichiometry unlikely to be associated with a transit-amplifying cell. Given that many

adult-born neurons undergo apoptosis, but there is no direct way to assess cell death over time, we examined whether our behavioral interventions could affect cellular survival to SB431542 datasheet account for differences in lineage trajectories (Figure S4A). We found that social isolation did not decrease cellular survival and that enrichment increased survival (Figure S4B) by a magnitude that could not account for the observed lineage gains (Figure 7J). We also assessed the numbers of cells undergoing apoptosis at time of sacrifice in each group in this study (Figures S4C–S4F). We did not detect differences in the number of apoptotic cells between our behavioral interventions (Figure S4C). Moreover, the number of cells undergoing apoptosis did not correlate with accumulation of EYFP+ cells across the groups (Figure S4D). We also did not detect differences in the number of cells undergoing apoptosis between the different age groups used in this study (at different time points) (Figures S4E and S4F). Thus, social isolation promoted accumulation of EYFP+ NSCs and instructed NSCs toward a linear relationship Selleckchem TSA HDAC with their terminal neuronal progeny. EEE promoted accumulation of EYFP+ neurons and instructed NSCs toward a variable relationship

with their terminal neuronal progeny. Here we report the first system that allows for inducible cre-mediated recombination in adult hippocampal radial GFAP-expressing NSCs, but not GFAP−Tbr2-expressing neural progenitors. Surprisingly, Thymidine kinase we observed an increase in the absolute number of EYFP+ NSCs over time. In the adult brain, radial astrocyte-like stem cells are currently considered to be “quiescent,” self-renewing, and are not thought to accumulate (Encinas et al., 2006). One recent lineage study suggested that NSCs undergo a limited and constant number of asymmetric divisions resulting in self-renewal only, followed by differentiation

into terminal astrocytes suggesting that NSCs are depleted with age (Encinas et al., 2011). However, an inherent limitation of genetically defined lineage studies is the potential for functional heterogeneity within the genetically defined stem cell. NSC heterogeneity was recently proposed in a report describing a nonradial multipotent cell with astrocyte-like properties (Lugert et al., 2010). While the lineal relationship of these horizontal cells to radial NSCs remains to be established, more horizontal cells were present in animals subjected to experimental seizure protocols. The latter finding suggests a stem cell dormancy hypothesis that is further supported by historical observations that even in aged animals, when baseline proliferation is minimal, EEE induces a robust increase in neurogenesis (Kempermann et al., 1998).