Department of Biology, University of Nevada, Reno, , 1664 North Virginia Street, MS 314, Reno, NV 89557, USA.
Proc Biol Sci. 2011 Jan 7;278(1702):138-43. doi: 10.1098/rspb.2010.0861. Epub 2010 Jul 21.
It has been hypothesized that individuals who have higher demands for spatially based behaviours should show increases in hippocampal attributes. Some avian species have been shown to use a spatially based representation of their environment during migration. Further, differences in hippocampal attributes have been shown between migratory and non-migratory subspecies as well as between individuals with and without migratory experience (juveniles versus adults). We tested whether migratory behaviour might also be associated with increased hippocampal neurogenesis, and whether potential differences track previously reported differences in hippocampal attributes between a migratory (Zonotrichia leucophrys gambelii) and non-migratory subspecies (Z. l. nuttalli) of white-crowned sparrows. We found that non-migratory adults had relatively fewer numbers of immature hippocampal neurons than adult migratory birds, while adult non-migrants had a lower density of new hippocampal neurons than adult and juvenile migratory birds and juvenile non-migratory birds. Our results suggest that neurogenesis decreases with age, as juveniles, regardless of migratory status, exhibit similar and higher levels of neurogenesis than non-migratory adults. However, our results also suggest that adult migrants may either seasonally increase or maintain neurogenesis levels comparable to those found in juveniles. Our results thus suggest that migratory behaviour in adults is associated with maintained or increased neurogenesis and the differential production of new neurons may be the mechanism underpinning changes in the hippocampal architecture between adult migratory and non-migratory birds.
有人假设，那些对基于空间的行为有更高要求的个体应该会表现出海马体属性的增加。已经有研究表明，一些鸟类在迁徙过程中会利用环境的基于空间的表示。此外，在具有迁徙经验的个体（幼鸟与成鸟）之间以及在具有迁徙经验的个体与不具有迁徙经验的个体（幼鸟与成鸟）之间，已经显示出海马体属性存在差异。我们测试了迁徙行为是否也与海马体神经发生的增加有关，以及潜在的差异是否与之前报道的在具有迁徙行为的（Zonotrichia leucophrys gambelii）和不具有迁徙行为的亚种（Z. l. nuttalli）之间的海马体属性差异有关。我们发现，不具有迁徙行为的成年个体的不成熟海马体神经元数量相对较少，而成年非迁徙个体的新海马体神经元密度低于成年和幼年迁徙个体以及幼年非迁徙个体。我们的研究结果表明，神经发生随着年龄的增长而减少，因为无论迁徙状态如何，幼鸟的神经发生水平都与非迁徙成年个体相似，而且更高。然而，我们的研究结果也表明，成年迁徙个体可能会季节性地增加或维持与幼鸟相似的神经发生水平。因此，我们的研究结果表明，成年个体的迁徙行为与维持或增加神经发生有关，而新神经元的差异产生可能是成年迁徙鸟类和不迁徙鸟类之间海马体结构变化的基础机制。
