The dentate gyrus (DG) is an important part of hippocampal formation and is believed to be involved in a variety of brain functions including episodic and spatial memory and the exploration of novel environments. In several neurodegenerative disorders, significant pathology occurs in the DG which may be involved in the development of clinical dementia. This book discusses the structure of the dentate gyrus as well as the role it plays in diseases and potential health implications.