The role of the ventral dentate gyrus in olfactory learning and memory and anxiety-based disorders

Dorsoventral lesion studies of the hippocampus (HPP) have suggested that the dorsal axis is important for spatial processing and the ventral axis is involved in olfactory learning and memory as well as anxiety. Accrued reports have indicated that subregions along the dorsal axis play specialized roles in spatial information processes and there is some evidence to indicate that the ventral CA3 and ventral CA1 subregions are involved in cued retrieval in fear conditioning and also carry out olfactory learning and memory processes similar to dorsal axis counterparts. The current study investigated the less-understood role of the ventral DG in olfaction and anxiety. A series of odor stimuli were used that provide a range of differentiation on only one level in a matching-to-sample paradigm to investigate ventral DG involvement in working memory for similar and less similar odors, in which there was a memory-based pattern separation effect. A novelty detection paradigm was used to investigate ventral DG involvement in recognition of familiar and new social odors. Finally, an elevated-plus maze and open field maze were selected in order to investigate the role of the ventral DG in the ability to modify behavior in potentially dangerous environments. The current study has provided evidence to suggest that the ventral DG plays an important role in olfactory learning and memory processes as well as anxiety-based behaviors during exploration in anxiety-provoking environments.