Brain Structure and Function

, Volume 220, Issue 1, pp 361–383

In contrast to many other mammals, cetaceans have relatively small hippocampi that appear to lack adult neurogenesis

  • Nina Patzke
  • Muhammad A. Spocter
  • Karl Æ. Karlsson
  • Mads F. Bertelsen
  • Mark Haagensen
  • Richard Chawana
  • Sonja Streicher
  • Consolate Kaswera
  • Emmanuel Gilissen
  • Abdulaziz N. Alagaili
  • Osama B. Mohammed
  • Roger L. Reep
  • Nigel C. Bennett
  • Jerry M. Siegel
  • Amadi O. Ihunwo
  • Paul R. Manger
Original Article

DOI: 10.1007/s00429-013-0660-1

Cite this article as:
Patzke, N., Spocter, M.A., Karlsson, K.Æ. et al. Brain Struct Funct (2015) 220: 361. doi:10.1007/s00429-013-0660-1

Abstract

The hippocampus is essential for the formation and retrieval of memories and is a crucial neural structure sub-serving complex cognition. Adult hippocampal neurogenesis, the birth, migration and integration of new neurons, is thought to contribute to hippocampal circuit plasticity to augment function. We evaluated hippocampal volume in relation to brain volume in 375 mammal species and examined 71 mammal species for the presence of adult hippocampal neurogenesis using immunohistochemistry for doublecortin, an endogenous marker of immature neurons that can be used as a proxy marker for the presence of adult neurogenesis. We identified that the hippocampus in cetaceans (whales, dolphins and porpoises) is both absolutely and relatively small for their overall brain size, and found that the mammalian hippocampus scaled as an exponential function in relation to brain volume. In contrast, the amygdala was found to scale as a linear function of brain volume, but again, the relative size of the amygdala in cetaceans was small. The cetacean hippocampus lacks staining for doublecortin in the dentate gyrus and thus shows no clear signs of adult hippocampal neurogenesis. This lack of evidence of adult hippocampal neurogenesis, along with the small hippocampus, questions current assumptions regarding cognitive abilities associated with hippocampal function in the cetaceans. These anatomical features of the cetacean hippocampus may be related to the lack of postnatal sleep, causing a postnatal cessation of hippocampal neurogenesis.

Keywords

Adult hippocampal neurogenesisHippocampusDoublecortinMemoryMammaliaCognition

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Nina Patzke
    • 1
  • Muhammad A. Spocter
    • 1
    • 2
  • Karl Æ. Karlsson
    • 3
  • Mads F. Bertelsen
    • 4
  • Mark Haagensen
    • 5
  • Richard Chawana
    • 1
  • Sonja Streicher
    • 6
  • Consolate Kaswera
    • 7
  • Emmanuel Gilissen
    • 8
    • 9
    • 10
  • Abdulaziz N. Alagaili
    • 11
  • Osama B. Mohammed
    • 11
  • Roger L. Reep
    • 12
  • Nigel C. Bennett
    • 6
    • 11
  • Jerry M. Siegel
    • 13
  • Amadi O. Ihunwo
    • 1
  • Paul R. Manger
    • 1
  1. 1.School of Anatomical SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
  2. 2.Department of AnatomyDes Moines UniversityDes MoinesUSA
  3. 3.Biomedical EngineeringReykjavik UniversityReykjavikIceland
  4. 4.Centre for Zoo and Wild Animal HealthCopenhagen ZooFrederiksbergDenmark
  5. 5.Department of Radiology, Donald Gordon Medical CentreUniversity of the WitwatersrandJohannesburgSouth Africa
  6. 6.Department of Zoology and EntomologyUniversity of PretoriaPretoriaSouth Africa
  7. 7.Faculté des SciencesUniversity of KisanganiKisanganiDemocratic Republic of Congo
  8. 8.Department of African ZoologyRoyal Museum for Central AfricaTervurenBelgium
  9. 9.Laboratory of Histology and NeuropathologyUniversité libre de BruxellesBrusselsBelgium
  10. 10.Department of AnthropologyUniversity of ArkansasFayettevilleUSA
  11. 11.KSU Mammals Research Chair, Department of ZoologyKing Saud UniversityRiyadhSaudi Arabia
  12. 12.Department of Physiological SciencesUniversity of FloridaGainsvilleUSA
  13. 13.Neurobiology Research, 151A3, Department of Psychiatry, Brain Research InstituteUCLA School of Medicine, Sepulveda VA Medical CentreNorth HillsUSA