Fascia dentata hippocampi

Dentate gyrus
Diagram of hippocampal regions. DG: Dentate gyrus.
Coronal section of brain immediately in front of pons. (Label for "Gyrus dentatus" is at bottom center.)
Details
Part of	Temporal lobe
Artery	Posterior cerebral Anterior choroidal
Identifiers
Latin	gyrus dentatus
MeSH	A08.186.211.577.405.200
NeuroNames	hier-161
NeuroLex ID	Dentate Gyrus
TA	A14.1.09.237 A14.1.09.339
FMA	61922
Anatomical terms of neuroanatomy []

The dentate gyrus is part of the hippocampus and/or hippocampal formation, as some texts include the latter structure in the former or vice versa. The dentate gyrus is thought to contribute to the formation of new episodic memories, the spontaneous exploration of novel environments, and other functions. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats (other sites include the olfactory bulb and cerebellum).

Granule cells within the molecular layer of the dentate gyrus receive the hippocampal formation's major excitatory input from the cortex. This input is primarily made up of signals from layer II of the entorhinal cortex and is the first connection of the trisynaptic loop, the hippocampal circuit.

The dentate gyrus is composed of unidirectional projections dispersed towards CA3 pyramidal cells of the hippocampus. It consists of three layers of neurons: molecular, granular, and polymorphic. The granular layer is most prominent and contains granule cells that project to the CA3 subfield of the hippocampus, as previously mentioned. These granule cells project mostly to interneurons, but also to pyramidal cells and are the principal excitatory neurons of the dentate gyrus. The major input to the dentate gyrus (the so-called perforant pathway) is from layer 2 of the entorhinal cortex, and the dentate gyrus receives no direct inputs from other cortical structures. The perforant pathway is divided into the medial and lateral perforant paths, generated, respectively, at the medial and lateral portions of the entorhinal cortex. The medial perforant path synapses onto the proximal dendritic area of the granule cells, whereas the lateral perforant path does so onto the distal dendrites of these same cells. Most lateral views of the dentate gyrus may appear to suggest a structure consisting of just one entity, but medial movement may provide evidence of the ventral and dorsal parts of the dentate gyrus.