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Cited by 2,180Memory and Neural MechanismsNeuroscience and Neuropharmacology ResearchNeurogenesis and neuroplasticity mechanisms

The three-dimensional organization of the hippocampal formation: A review of anatomical data

Amaral, D.G., Witter, M.P.·1989·Neuroscience
DOI 10.1016/0306-4522(89)90424-7
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Abstract

In the early 1970s, Andersen and colleagues proposed that the principal excitatory pathways of the hippocampal formation were organized in a lamellar fashion. This proposition, based heavily on the physiological studies of the proponents, indicated that "a point source of entorhinal activity projects its impulses through the four membered pathway (of the hippocampal formation) along a slice or lamella, of hippocampal tissue oriented normally to the alvear surface" [Anderson P., Bliss V.P. and Skrede K. K. (1971) Expl Brain Res. 13, 222-238] and perpendicular to the long axis of the hippocampus. Andersen et al. further suggested that, "By means of this lamellar organization, small strips of the hippocampal cortex may operate as independent functional units, although excitatory and inhibitory transverse connections may modify the behavior of neighboring lamellae." The "lamellar hypothesis" of hippocampal anatomical organization has had tremendous influence on the conceptualization of hippocampal information processing and was largely responsible for prompting the establishment of the in vitro hippocampal slice technology. While the "lamellar hypothesis" was consistent with the known neuroanatomy, subsequent neuroanatomical investigations, using a variety of modern tracing techniques, have invariably demonstrated that all of the major hippocampal projections, except for those arising from the granule cells of the dentate gyrus, are much more divergent than would be consistent with a strict interpretation of the lamellar hypothesis. This has become particularly clear in ongoing studies of the intrinsic hippocampal projections using the recently introduced anterograde tracer, Phaseolus vulgaris leucoagglutinin. Citing the conclusions from several papers dealing with the anatomical organization of the hippocampal formation and using examples from recent Phaseolus vulgaris leucoagglutinin mapping studies, the following are demonstrated. (1) That the major hippocampal projections are as extensive and highly organized in the long or septotemporal axis of the hippocampus as in the transverse axis. (2) That at least some of the hippocampal projections, such as the associational projections arising from the dentate gyrus, appear to be specifically organized to integrate distant levels of the hippocampal formation. (3) That the physiological data of Anderson et al. can be re-interpreted in the light of these new anatomical data to show how the stimulation and recording protocols used at the time would, in fact, generate the appearance of a lamellar organization. It is concluded that it is heuristically most reasonable to consider the hippocampal formation as a three-dimensional cortical region with important information processing taking place in both the transverse and long axes.(ABSTRACT TRUNCATED AT 400 WORDS)

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  • In rodents, the hippocampal formation system consists of several structures connected within a loop: entorhinal cortex, dentate gyrus, CA3, CA1, and subiculum, with specified inputs and outputs.

    “In rodents, this system consists of several structures connected within a loop that encompasses (Figure 9) the entorhinal cortex (EC), with inputs from higher sensory cortices; dentate gyrus (DG), with inputs from EC; CA3, with 'external' inputs from EC and DG and 'internal' inputs from CA3; CA1, with inputs from CA3 and EC; and subiculum(SUB), with inputs from CA1 and outputs to EC (Lorente de No”

    From The essential role of hippocampal CA1 NMDA receptor-dependent synaptic plasticity in spatial memory. (1996) · cites this paper as Amaral and Witter, 1989

  • Evidence from neuroanatomical studies of individuals with depression and suicidal behaviour have demonstrated changes in density of glutamatergic neurons and glial cells, and the volume of the hippocampus.

    “Evidence from neuroanatomical studies of individuals with depression and suicidal behaviour have demonstrated changes in density of glutamatergic neurons and glial cells 161,162 , and the volume 163 of the hippocampus, which relies on excitatory neurotransmission via glutamatergic signalling and is involved in learning and memory 164 .”

    From Suicide and suicide risk (2019) · cites this paper as [164]

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Authors
Amaral, D. G., & Witter, M. P.
Affiliations
  • Salk Institute for Biological Studies (US)
  • Vrije Universiteit Amsterdam (NL)
Corresponding author
Amaral, D.G.
ORCID
Venue
Neuroscience
Publisher
Elsevier BV
Published
1989-01
Volume
31
Issue
3
Pages
571-591
ISSN
0306-4522 (ISSN-L)
DOI
10.1016/0306-4522(89)90424-7
OpenAlex
W2142925815
Cited by
2,180
References
0
Citations by year
2026: 49 · 2025: 64 · 2024: 56 · 2023: 52 · 2022: 69 · 2021: 92 · 2020: 57 · 2019: 81 · 2018: 80 · 2017: 69 · 2016: 57 · 2015: 76 · 2014: 82 · 2013: 80 · 2012: 61
FWCI
5.75
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Neuroscience (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Institute of Neurological Disorders and Stroke (NS 16980)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Memory and Neural Mechanisms
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Life Sciences › Neuroscience › Developmental Neuroscience › Neurogenesis and neuroplasticity mechanisms
Keywords
hippocampal formation, hippocampal projections, entorhinal cortex, dentate gyrus, Phaseolus vulgaris leucoagglutinin, anterograde tracing, septotemporal axis, hippocampal slices
MeSH terms
Animals, Hippocampus, Rats

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