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

TY - JOUR

T1 - In contrast to many other mammals, cetaceans have relatively small hippocampi that appear to lack adult neurogenesis

AU - Patzke, Nina

AU - Spocter, Muhammad A.

AU - Karlsson, Karl Æ.

AU - Bertelsen, Mads Frost

AU - Haagesen, Mark

AU - Chawana, Richard

AU - Streicher, Sonja

AU - Kaswera, Consolate

AU - Gilissen, Emmanuel

AU - Alagili, Abdulaziz N.

AU - Mohammed, Osama B.

AU - Reep, Roger L.

AU - Bennett, Nigel C.

AU - Siegel, Jerry M.

AU - Ihunwo, Amadi O.

AU - Manger, Paul R.

PY - 2013/1

Y1 - 2013/1

N2 - 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.

AB - 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.

KW - Faculty of Health and Medical Sciences

KW - Adult hippocampal neurogenesis

KW - Hippocampus

KW - Doublecortin

KW - Memory

KW - Mammalia

KW - Cognition

KW - Adult hippocampal neurogenesis

KW - Hippocampus

KW - Doublecortin

KW - Memory

KW - Mammalia

KW - Cognition

U2 - 10.1007/s00429-013-0660-1

DO - 10.1007/s00429-013-0660-1

M3 - Journal article

SN - 1863-2653

VL - 220

SP - 361

EP - 383

JO - Brain Structure & Function

JF - Brain Structure & Function

IS - 1

ER -