Figure 1: AHN is important for cognitive and emotional learning. The newly born neurons continuously generated in the postnatal hippocampus are believed to regulate cognitive and emotional tasks, as occurs in the contextual fear learning paradigm and the spatial learning assessed in the MWM. In contextual fear learning, the hippocampus is thought to be essential for the association between a previously neutral context and an aversive stimulus (in this case, a mild footshock) leading to a fear response (conditioned freezing) when the individual is reexposed to the context where the fear learning occurred. In the case of spatial learning, as assessed by the MWM, hippocampal cells are believed to play an important role in the cued spatial navigation strategies that make it possible for the rodent to more quickly find the hidden platform across the test trials. AHN = adult hippocampal neurogenesis; MWM = Morris water maze.