研究人员在日前在线出版的《自然—神经科学》期刊上报告，成年大脑需要持续不断的新生神经细胞来维持嗅觉和空间探索等区域的功能。
直至最近几年前，一种流行的观点还认为，成年大脑会渐渐失去神经细胞，却不会生长新的神经细胞。如今，这种观点已经被颠覆，但科学家们还是不知道少数新产生的神经细胞究竟会发挥什么样的重要作用。
Ryoichiro Kageyama和同事探讨了这个问题。通过基因工程改造，他们培养出一种小鼠，这种小鼠会在所有成年时出生的神经细胞中合成了一种荧光蛋白质，他们在一年的时间中记录了荧光神经细胞的数量。在这一时间段里，在嗅球细胞某一层中的神经细胞基本被新细胞完全置换了。大脑的海马区域对空间学习和记忆至关重要，这一区域也新增加大约15%的新细胞。
中止神经细胞的生长是否会影响小鼠的嗅觉和学习能力呢？Kageyama和同事培育了另一种类的小鼠，它们会在成年神经细胞的前体中生成一种有毒蛋白质，从而杀死新生细胞。没有了新细胞，小鼠的嗅球变小了，但它们的嗅觉能力在4个月的时间时维持不变，说明这一区域有多余细胞。相反，指导小鼠在迷宫里导航的记忆能力却消失了。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature Neuroscience，doi:10.1038/nn.2185，Itaru Imayoshi，Ryoichiro Kageyama
Roles of continuous neurogenesis in the structural and functional integrity of the adult forebrain
Itaru Imayoshi1,2,3, Masayuki Sakamoto1,2, Toshiyuki Ohtsuka1,3, Keizo Takao4,5,6, Tsuyoshi Miyakawa4,5,6, Masahiro Yamaguchi7, Kensaku Mori7, Toshio Ikeda8,9, Shigeyoshi Itohara8 & Ryoichiro Kageyama1,3
Abstract
Neurogenesis occurs continuously in the forebrain of adult mammals, but the functional importance of adult neurogenesis is still unclear. Here, using a genetic labeling method in adult mice, we found that continuous neurogenesis results in the replacement of the majority of granule neurons in the olfactory bulb and a substantial addition of granule neurons to the hippocampal dentate gyrus. Genetic ablation of newly formed neurons in adult mice led to a gradual decrease in the number of granule cells in the olfactory bulb, inhibition of increases in the granule cell number in the dentate gyrus and impairment of behaviors in contextual and spatial memory, which are known to depend on hippocampus. These results suggest that continuous neurogenesis is required for the maintenance and reorganization of the whole interneuron system in the olfactory bulb, the modulation and refinement of the existing neuronal circuits in the dentate gyrus and the normal behaviors involved in hippocampal-dependent memory.
1 Institute for Virus Research, Kyoto University, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507, Japan.
2 Kyoto University Graduate School of Biostudies, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
3 Japan Science and Technology Agency, CREST, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507, Japan.
4 Kyoto University Graduate School of Medicine, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
5 Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
6 Institute for Bioinformatics Research and Development and CREST, 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan.
7 Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
8 RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
9 Present address: National Institute for Longevity Sciences, 36-3, Gengo, Morioka, Obu, Aichi 474-8511, Japan.
