The Cornu Ammonis (CA) subfield forms the area between dentate gyrus and the subiculum and is also referred to as the 'hippocampus proper'. It is subdivided into subfields CA3, CA2 and CA1, according to the nomenclature of Lorente de Nó (1934). The polymorphic layer of the dentate gyrus is sometimes referred to as CA4, also defined by Lorente de Nó (1934). However, the existence of CA4 is disputed and we do not delineate this subdivision in this connectome.
In this description of the stratification/lamination of the Cornu Ammonis, the most superficial layer, close to the pial surface of the brain comes first, followed by the layers below. The stratification of the Cornu Ammonis is largely the same for all subfields. The main difference is that CA3 has a layer called the stratum lucidum, whereas this layer is absent in CA2 and CA1. Below, the layers of CA3, CA2 and CA1 are summarized.
Several good overviews exist, mostly tailored towards the physiology of interneurons (e.g. Freund and Buzsaki, 1996; Klausberger, 2009). An online repository containing all known cell types of the hippocampal formation and their characteristics exists at: wwww.hippocampome.org
The animation above displays a CA3 (left) and CA1 (right) pyramidal neuron. The cells were reconstructed by Ishizuka, 1995 and downloaded from neuromorpho.org (Ascoli, 2018).
Boccara, C. N., Kjonigsen, L. J., Hammer, I. M., Bjaalie, J. G., Leergaard, T. B., & Witter, M. P. (2015). A three-plane architectonic atlas of the rat hippocampal region. Hippocampus, 25(7), 838–857. CA1 in Hippocampus Atlas | CA2 in Hippocampus Atlas | CA3 in Hippocampus Atlas
Dudek S.M., Alexander G.M. & Farris S. (2016) Rediscovering area CA2: unique properties and functions. Nat Rev Neurosci, 17(2), 89-102.
Akram M.A., Nanda S., Maraver P., Armañanzas R. & Ascoli G.A. (2018). An open repository for single-cell reconstructions of the brain forest. Sci Data Resolve DOI
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© Copyright 2007 - 2023 N.L.M. Cappaert & N.M. van Strien. All rights reserved. Content is available under Attribution-Noncommercial-No Derivative Works 3.0 Unported. Currently this work is financially supported by the Dutch Research Council. Project DOI: 10.21942/uva.19786213.v1