Cited by 976Memory and Neural MechanismsNeuroscience and Neuropharmacology ResearchNeurogenesis and neuroplasticity mechanisms

The DOI matches its Crossref record; 44 of the 44 references it cites were found in a registry or an index; none of the 27 sources its claims cite is checked for support yet.

The hippocampal CA2 region is essential for social memory

Open access

Abstract

The hippocampus is critical for encoding declarative memory, our repository of knowledge of who, what, where and when. Mnemonic information is processed in the hippocampus through several parallel routes involving distinct subregions. In the classic trisynaptic pathway, information proceeds from entorhinal cortex (EC) to dentate gyrus to CA3 and then to CA1, the main hippocampal output. Genetic lesions of EC (ref. 3) and hippocampal dentate gyrus (ref. 4), CA3 (ref. 5) and CA1 (ref. 6) regions have revealed their distinct functions in learning and memory. In contrast, little is known about the role of CA2, a relatively small area interposed between CA3 and CA1 that forms the nexus of a powerful disynaptic circuit linking EC input with CA1 output. Here we report a novel transgenic mouse line that enabled us to selectively examine the synaptic connections and behavioural role of the CA2 region in adult mice. Genetically targeted inactivation of CA2 pyramidal neurons caused a pronounced loss of social memory—the ability of an animal to remember a conspecific—with no change in sociability or several other hippocampus-dependent behaviours, including spatial and contextual memory. These behavioural and anatomical results thus reveal CA2 as a critical hub of sociocognitive memory processing.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

A newly generated Amigo2-Cre mouse line allowed selective targeting of hippocampal CA2 pyramidal neurons, showing that CA2 receives distinct entorhinal and subcortical inputs and projects mainly within hippocampus. Inactivating CA2 output with tetanus toxin selectively abolished social memory while sparing sociability, spatial memory, contextual/auditory fear memory, anxiety, locomotion, and olfaction.

Key findings

  • The Amigo2-Cre line selectively labeled CA2 pyramidal neurons: 97.38 ± 0.31% of YFP+ cells co-stained for RGS14 (n = 4 mice, 2546 cells), 82.33 ± 2.37% of RGS14+ cells were YFP+ (n = 4 mice, 2992 cells), and only 0.16 ± 0.16% of YFP+ neurons were GABA+ (n = 3 mice, 1539 cells).
  • CA2 inactivation with eGFP-TeNT blocked CA2→CA1 synaptic transmission: light-evoked monosynaptic PSPs in CA1 had mean latency 1.22 ± 0.06 ms (n = 119 observations) in controls, but TeNT co-expression produced little or no synaptic response.
  • CA2-TeNT mice showed a profound social memory deficit: they failed to prefer a novel mouse in the three-chamber social novelty test, showed suppressed social memory in the direct interaction test after a 1-h inter-trial interval, and showed no habituation/dishabituation in the 5-trial social memory assay.
  • CA2 inactivation did not alter sociability, locomotor activity, anxiety-like behavior, Morris water maze spatial memory, contextual fear memory, auditory fear memory, novel object recognition, buried food detection, or olfactory habituation/dishabituation.

Methods

  • Generated an Amigo2-Cre BAC transgenic mouse line, backcrossed to C57BL/6J at least 6 times; only Cre+ males >8 weeks old were used, with Cre-dependent AAVs stereotaxically injected into dorsal hippocampus and experiments performed 2–4 weeks later.
  • Used Cre-dependent YFP for anatomical tracing, EnvA pseudotyped ΔG rabies virus for monosynaptic input mapping, immunohistochemistry/confocal microscopy for cell-type validation, and slice electrophysiology with ChR2 and TeNT to test CA2→CA1 transmission.
  • Compared CA2-YFP controls with CA2-TeNT mice across open field, elevated plus maze, novel object, Morris water maze, fear conditioning, three-chamber sociability/social novelty, direct interaction, 5-trial social memory, buried food, and olfactory habituation/dishabituation tests; statistics used t-tests, 2-way ANOVA, or 2-way RM ANOVA with Holm-Sidak correction, P < 0.05.

Limitations

  • The paper states that the results do not rule out a more general role for CA2 in hippocampal-dependent memory tasks; other hippocampal regions may compensate, or CA2 may be selectively required for more demanding non-social memory tasks.
  • The paper notes that failure to observe vasopressinergic input to CA2 may reflect the rabies tracing system’s inability to label peptidergic inputs; absent CA2 output to supramammillary nucleus may reflect an inhibitory projection, and absent CA2 output to EC layer II may reflect weak connections not detected by anterograde tracing.
  • Evident from the text: only male Cre+ mice were studied, and only dorsal CA2 was targeted; the Amigo2-Cre line also expresses Cre outside CA2 in adult brain and during development, requiring AAV restriction to CA2.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/nature13028

Cites

44 of 44 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 27 cited sources checked · 0 supported · 0 flagged

Show all 24 claims

  • It may state two separate claims as one. 23
  • Probably not a substantial claim. 28
  • The quote only partly states this claim. 1
45 of 45
  • The paper relies on this without support.

    The functional properties and behavioral role of CA2 are largely unknown.

    “Although the CA2 region was first described by Lorente de Nó in 19348 relatively little is known about its functional properties and behavioral role.”
  • The paper relies on this without support.

    The olfactory habituation/dishabituation test validly measures detection and discrimination of social and non-social odors.

    “we used an olfactory habituation/dishabituation test (Extended Data Fig. 9b) and found that CA2 inactivation also had no effect on the ability of the mice to detect or discriminate either non-social or social odors.”
  • The paper relies on this without support.

    The novel object recognition protocols validly measure interest in novelty.

    “the CA2-TeNT mice demonstrated normal preference for a novel object as assayed by two different novel object recognition protocols (Extended Data Fig. 8).”
  • The paper relies on this without support.

    The buried food test validly measures non-social odor detection.

    “CA2-TeNT mice showed no loss in the ability to detect the presence of food buried under a deep layer of cage bedding, a test of non-social odor detection (Extended Data Fig. 9a).”
  • The paper relies on this without support.

    Contextual fear memory is hippocampal-dependent and auditory fear memory is amygdala-dependent.

    “A 3-day delay fear conditioning protocol was employed to test hippocampal-dependent contextual fear memory and amygdala-dependent auditory fear memory.”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Citations

Cites

Flagged first, then by citations

Show all 44 references

Research works printed but not linked: 3

  1. Heintz, N. GENSAT Brain Atlas of gene expression in EGFP Transgenic Mice http://www.gensat.org (2003)
  2. Lein, E. S. ISH Data: Allen Brain Atlas: Mouse Brain http://mouse.brain-map.org/ (2007)
  3. de Jong, P. J. BAC Clones Distribution Center – BACPAC Resources Center https://bacpac.chori.org/ (2000)

Cited by

Sorted by citations

Items 101–200 of 957

Metadata

Authors
Hitti, F. L., & Siegelbaum, S. A.
Affiliations
  • Columbia University (US)
  • Howard Hughes Medical Institute (US)
Corresponding author
Siegelbaum, Steven A.
Venue
Nature
Published
2014-02-23
Volume
508
Issue
7494
Pages
88-92
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
OpenAlex
W2011504521
Cited by
976
References
44
Citations by year
2026: 77 · 2025: 103 · 2024: 98 · 2023: 113 · 2022: 103 · 2021: 101 · 2020: 67 · 2019: 70 · 2018: 87 · 2017: 53 · 2016: 54 · 2015: 32 · 2014: 17
FWCI
29.01
Type
journal article
Language
en
Open access
Locations
  • Nature (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
  • Howard Hughes Medical Institute
  • National Institute of Mental Health (F30MH098633)
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
social memory, neural inactivation, transgenic mice, entorhinal cortex, contextual memory, spatial memory, sociability, autism spectrum disorder, schizophrenia, hippocampal subfields
MeSH terms
Animals, Autistic Disorder, Electrophysiology, Female, Male, Memory, Mice, Inbred C57BL, Mice, Transgenic, Schizophrenia, Social Behavior, Space Perception, Synapses, Pyramidal Cells, Integrases, Mice, CA2 Region, Hippocampal

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-10-09, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-09 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review