Recently, it has been argued that classical hippocampal-dependent learning paradigms do not accurately reflect the role of the dentate gyrus (Deng et al., 2010). Computational work suggests that the dentate gyrus may be involved specifically in pattern separation, the process where highly similar, overlapping cortical representations are separated to keep them independent in episodic memory (O’Reilly & McClelland, 1994). Some evidence suggests that new neurons may be important for the ability of the dentate gyrus to separate patterns (Deng et al., 2010). Increased adult neurogenesis has been linked to enhanced spatial pattern separation in mice (Creer et al., 2010). Conversely, ablation of new neurons in the dentate gyrus produces deficits in spatial pattern separation in mice (Clelland et al., 2009). Taken together, the available evidence suggests that stress-reduced adult neurogenesis in the dentate gyrus may have profound effects on hippocampal-dependent memory formation and learning although the specific functions affected remain undetermined.
