The Role of the Dentate Gyrus in Mediating Hippocampal Functions: The Healthy Brain

The dentate gyrus (DG), which is part of the hippocampal formation, is the main target of neocortical and subcortical afferents received by the hippocampus, and this forms the anatomical basis for its role in cognitive processes such as attention and memory. The DG is involved in organizing many of the cognitive functions of the hippocampus and the brain as a whole, including novelty detection, pattern separation, pattern completion, spatial working memory, information encoding, and memory consolidation. Long-term potentiation – plastic changes in synapses similar to those occurring when information is memorized – was first discovered in the DG. The DG is a unique region of the brain, one of the few where neurogenesis occurs in adult mammals, including humans. Another feature of the DG distinguishing it from the hippocampus is that it contains two types of glutamatergic neurons – granule cells and mossy cells. Granule cells, which normally have low activity, limit the excitability of hippocampal pyramidal neurons in adverse conditions. The functions of mossy neurons in the DG are the least well understood; these cells, innervating both glutamatergic and GABAergic neurons, are likely to be involved in the organization of complex network activity both in the DG itself and in the hippocampus. Despite intensive research on the DG, its role in the hippocampal activity is still largely unclear. This review discusses the anatomical, histochemical, and functional features of the DG, the activity of its individual cellular elements, and its role in the hippocampal functions of the normal brain.