新研究表明特定区域的脑中，新生神经元在早期发育过程中的经历，会影响它们在成年脑中的存活和活性。这些新生神经元存储这些经历的方式，可以用以解释它们如何影响成年个体学习和记忆的过程。美国Salk研究所的Fred Gage领导研究小组完成了此项研究。
研究者发现：经历可以加强脑中齿状回（*）区域的新生神经元的存活，而且相同经历的出现会激活更多这类的神经元。这种功能上的转变可能是长期记忆（**）的内在机制。研究文章发表在3月21日的《The Journal of Neuroscience》杂志上。
“研究结果识别出了一个特定的时期，在这个时期经历可以增强海马（***）中新生神经元的存活，”普林斯顿大学的Elizabeth Gould介绍说，他没有参与此项研究。海马包括齿状回这一区域。
Gage介绍说：“今后的研究将会致力于在记忆相关的行为过程中，经历是如何影响神经元的活性的，以及这对于其他的脑区域有何影响。”感兴趣的读者可以参看英文原文。
部分英文原文：
The Journal of Neuroscience, March 21, 2007, 27(12):3252-3259; doi:10.1523/JNEUROSCI.4941-06.2007
Experience-Specific Functional Modification of the Dentate Gyrus through Adult Neurogenesis: A Critical Period during an Immature Stage
Ayumu Tashiro, Hiroshi Makino, and Fred H. Gage
Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037
Correspondence should be addressed to Fred H. Gage, 10010 North Torrey Pines Road, La Jolla, CA 92037. Email: gage@salk.edu
Neural circuits in the dentate gyrus are continuously modified by adult neurogenesis, whose level is affected by the animal's experience. However, it is not known whether this experience-dependent anatomical modification alters the functional properties of the dentate gyrus. Here, using the expression of immediate early gene products, c-fos and Zif268, as indicators of recently activated neurons, we show that previous exposure to an enriched environment increases the total number of new neurons and the number of new neurons responding to reexposure to the same environment. The increase in the density of activated new neurons occurred specifically in response to exposure to the same environment but not to a different experience. Furthermore, we found that these experience-specific modifications are affected exclusively by previous exposure around the second week after neuronal birth but not later than 3 weeks. Thus, the animal's experience within a critical period during an immature stage of new neurons determines the survival and population response of the new neurons and may affect later neural representation of the experience in the dentate gyrus. This experience-specific functional modification through adult neurogenesis could be a mechanism by which new neurons exert a long-term influence on the function of the dentate gyrus related to learning and memory.
Key words: enriched environment; c-fos; zif268; immediate early gene; dentate gyrus; hippocampus; memory; neurogenesis
