Entorhinal Grid Cells May Facilitate Pattern Separation in the Hippocampus

Abstract

The dentate gyrus (DG) in the hippocampus of the mammalian brain is known to exhibit strong pattern separation. However, how this pattern separation arises in the DG is not well understood. Here we offer a novel hypothesis regarding this problem by demonstrating that pattern separation can already be performed by entorhinal grid cells, which are located just one synapse upstream of the DG. For our simulations we utilize a recently introduced grid cell model that interprets the behavior of grid cells as just one instance of a general information processing scheme. The obtained results challenge the established view that pattern separation occurs primarily in the DG, and they uncover a common misconception regarding the specificity of ensemble activity in grid cells.