The seasonal pattern of cell proliferation and neuron number in the dentate gyrus of wild adult eastern grey squirrels
The seasonal pattern of cell proliferation and neuron number in the dentate gyrus of wild adult eastern grey squirrels
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DOI：
10.1046/j.1460-9568.2000.00949.x
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发表时间：
2000-02-01
影响因子：
3.4
通讯作者：
Jacobs, LF
中科院分区：
文献类型：
--
作者：
Lavenex, P;Steele, MA;Jacobs, LF
齿状回是哺乳动物成年后产生神经元的两个大脑区域之一。在哺乳动物和鸟类中，神经发生（新神经元的增殖、存活和分化）受到经验的调节，神经发生的增加似乎与空间学习能力的提高有关。我们测试了这样一种假设，即在分散储存食物的长寿哺乳动物中，空间记忆处理的季节性变化（即在秋季贮藏季节增加处理）可能与齿状回（gcl DG）颗粒细胞层神经发生和神经元数量的变化有关。研究了野生成年东部灰松鼠（Sciurus carolinensis）在一年中的10月、1月和6月3个不同时间颗粒细胞层细胞增殖率和神经元总数。我们发现颗粒细胞层的细胞增殖率和神经元总数没有季节差异。我们的发现与之前在实验室小鼠和大鼠、自由放养、食物储存、黑冠山雀中进行的研究一致，也与目前关于神经发生和学习之间关系的假设一致。然而，我们的结果也与假设一致，即齿状回中的神经发生代表了一种可能受环境因素调节的维持系统，并且先前在啮齿动物中报道的总神经元数量的变化代表了发育变化而不是成年可塑性。在成熟的野生啮齿动物（如自由放养的松鼠）中观察到的模式，可能更准确地代表了成年哺乳动物海马的可塑性程度。
The dentate gyrus is one of two areas in the mammalian brain that produces neurons in adulthood. Neurogenesis (proliferation, survival, and differentiation of new neurons) is regulated by experience, and increased neurogenesis appears to be correlated with improved spatial learning in mammals and birds. We tested the hypothesis that in long-lived mammals that scatter-hoard food, seasonal variations in spatial memory processing (i.e. increased processing during caching season in the autumn) might correlate with changes in neurogenesis and neuron number in the granule cell layer of the dentate gyrus (gcl DG). We investigated the rate of cell proliferation and the total number of neurons in the granule cell layer of wild adult eastern grey squirrels (Sciurus carolinensis) at three different times of the year (October, January and June). We found no seasonal differences in cell proliferation rate or in total neuron number in the granule cell layer. Our findings are in agreement with those of previous studies in laboratory mice and rats, and in free-ranging, food-caching, black-capped chickadees, as well as with current hypotheses regarding the relationship between neurogenesis and learning. Our results, however, are also in agreement with the hypothesis that neurogenesis in the dentate gyrus represents a maintenance system that may be regulated by environmental factors, and that changes in total neuron number previously reported in rodents represent developmental changes rather than adult plasticity. The patterns observed in mature wild rodents, such as free-ranging squirrels, may represent more accurately the extent of hippocampal plasticity in adult mammals.