The hippocampal formation is a compound structure in the medial temporal lobe of the brain. There is no consensus concerning which brain regions are encompassed by the term, with some authors defining it as the dentate gyrus, the hippocampus proper and the subiculum;[1] and others including also the presubiculum, parasubiculum, and entorhinal cortex.[2] The hippocampal formation is thought to play a role in memory, spatial navigation and control of attention.