The hippocampal memory indexing theory.

TLDR

The hippocampal formation is implicated in information storage models of the mammalian brain, yet its precise role in memory remains unclear. The study proposes that the hippocampus forms and retains an index of neocortical areas activated by experiential events. The hippocampal index is hypothesized to be encoded via long‑term potentiation, representing unique cortical regions activated by events, and its reactivation is thought to reactivate those cortical areas, producing a memorial experience and possibly establishing a cortical memory trace.

Abstract

The hippocampal formation (comprising the hippocampus proper, the dentate gyrus, and the subiculum) has been repeatedly implicated in information storage models of the mammalian brain. The precise nature of the hippocampal role in the storage of information has, however, remained elusive. Here it is proposed that the role of the hippocampus is to form and retain an index of neocortical areas activated by experiential events. The hippocampal index, thus, represents those unique cortical regions activated by specific events. The neuronal mechanism underlying the memory index is hypothesized to be long-term potentiation. It is asserted that the reactivation of the stored hippocampal memory index will serve to also reactivate the associated unique array of neocortical areas and thus will result in a memorial experience. This hippocampal reactivation of a neocortical array may also be involved in establishing a cortically based memory trace.