為什么有的人能夠輕松準(zhǔn)確地記住很久以前的事情,，卻在日常生活中顯得很健忘呢？根據(jù)美國(guó)科學(xué)家的最新研究,，他們大腦中儲(chǔ)存了太多的沒(méi)用的舊信息,，以至于很難迅速地過(guò)濾日常的海量信息，并且很難分析和儲(chǔ)存短期記憶,。通俗地講,，就是“舊的不去，新的不來(lái)”,。
《美國(guó)國(guó)家科學(xué)院院刊》（PNAS）2007年3月13日發(fā)表的這篇文章指出,，即使一些看上去很好的事情，比方說(shuō)大腦中負(fù)責(zé)學(xué)習(xí)和記憶的海馬區(qū)的新的神經(jīng)元的生長(zhǎng),，也就是神經(jīng)發(fā)生（neurogenesis）,，也未必一定是一件好事。
論文的首席作者之一,、哥倫比亞大學(xué)醫(yī)學(xué)院的Gael Malleret博士說(shuō)：“我們吃驚地發(fā)現(xiàn)神經(jīng)生長(zhǎng)緩慢可以提高短期記憶，這意味著記得太多未必是一件好事,，忘卻對(duì)于正常的思考和行動(dòng)是很重要的,。”
這與傳統(tǒng)的看法相反。很多科學(xué)家一直以為海馬區(qū)的神經(jīng)生長(zhǎng)肯定對(duì)記憶有好處,。但是Malleret等人提出了相反的假設(shè),，并且設(shè)計(jì)了小鼠模型來(lái)測(cè)試這一假設(shè)。結(jié)果他們發(fā)現(xiàn)，神經(jīng)生長(zhǎng)被抑制的小鼠比其它小鼠能夠能快更好地在迷宮中找到食物,。
Malleret說(shuō)：“總的說(shuō)來(lái),，我們的發(fā)現(xiàn)表明海馬區(qū)的神經(jīng)元在某些情況下在不同的記憶存儲(chǔ)過(guò)程中扮演不同的角色。過(guò)多的神經(jīng)生長(zhǎng)對(duì)一些記憶功能是有害的,。”Malleret認(rèn)為,，他們的發(fā)現(xiàn)在醫(yī)療和人工智能等多個(gè)領(lǐng)域具有廣泛的意義。
部分英文原文：
Published online before print March 5, 2007, 10.1073/pnas.0611718104
PNAS | March 13, 2007 | vol. 104 | no. 11 | 4642-4646
Paradoxical influence of hippocampal neurogenesis on working memory
Michael D. Saxe*, Gaël Malleret*, Svetlana Vronskaya*, Indira Mendez*, A. Denise Garcia, Michael V. Sofroniew, Eric R. Kandel*,,, and René Hen*,
*Center for Neurobiology and Behavior and Howard Hughes Medical Institute, Columbia University, 722 West 168th Street, New York, NY 10032; and Department of Neurobiology and Brain Research Institute, University of California, Los Angeles, CA 90095
Contributed by Eric R. Kandel, January 3, 2007 (received for review December 18, 2006)
To explore the function of adult hippocampal neurogenesis, we ablated cell proliferation by using two independent and complementary methods: (i) a focal hippocampal irradiation and (ii) an inducible and reversible genetic elimination of neural progenitor cells. Previous studies using these methods found a weakening of contextual fear conditioning but no change in spatial reference memory, suggesting a supportive role for neurogenesis in some, but not all, hippocampal-dependent memory tasks. In the present study, we examined hippocampal-dependent and -independent working memory using different radial maze tasks. Surprisingly, ablating neurogenesis caused an improvement of hippocampal-dependent working memory when repetitive information was presented in a single day. These findings suggest that adult-born cells in the dentate gyrus have different, and in some cases, opposite roles in distinct types of memory.
hippocampus | irradiation | radial maze | interference
Freely available online through the PNAS open access option.
