More recent studies have linked adult neurogenesis with anxiety regulation and feedback of the stress response. Experimental manipulations associated with reduced number of new neurons in the dentate gyrus are associated with increased anxiety-like behavior (Bergami et al., 2009; Revest et al., 2009). Likewise, reduced adult neurogenesis is associated with impaired modulation of the HPA axis – corticosterone levels show a delayed return to baseline after stress in mice lacking new neurons. Furthermore, reduced neurogenesis is associated with impaired responsiveness of the HPA axis to a dexamethasone suppression test (Snyder et al., 2010). Taken together, these findings suggest that new neurons may play an important role not only in the cognitive functions of the hippocampus, but also in its anxiety and stress regulatory functions. The extent to which stress-induced reductions in adult neurogenesis contribute to increased pathological processes associated with chronic stress, such as anxiety and HPA axis dysregulation, remains to be determined.
