人们常常会想：人的大脑到底被利用了百分之多少？美国科学家的一项最新研究确定了大脑分配细胞进行编码和记忆存储的关键机制——一种名为CREB的蛋白。在这种蛋白影响下，人类中脑只有20%的神经细胞用于形成记忆。该研究成果为治疗阿尔海默症等脑部疾病开辟了新的道路。相关论文发表在4月20日的《科学》杂志上。
美国加州大学洛杉矶分校和加拿大多伦多大学的科学家的联合研究发现，这种CREB蛋白控制着大脑中神经元参与记忆形成的几率。
加州大学洛杉矶分校 David Geffen医学院神经生物学家和精神病专家、该研究项目负责人Alcino Silva表示，“记忆的产生并不是有意识的行为，而是人们通过学习激发大脑产生一系列化学物质，从而影响记忆的产生、维持和丧失。”
此前的研究已经表明，CREB蛋白对于维持记忆的稳定有重要意义。Silva表示，“我们猜测CREB在引导大脑细胞的记忆存储上，也起着至关重要的作用。”
通过对小鼠模型进行研究，Silva和同事来验证了他们的假设。研究人员先将CREB蛋白转入一种病毒，而后将该病毒导入小鼠大脑杏仁核区域（amygdala，大脑中的重要的情感记忆区域）的一些神经细胞。随后，科学家测定了小鼠回忆起自己笼子的能力，这种笼子具有特定图案的墙壁和独特的气味。
为了更加直观地了解哪些大脑细胞存储着小鼠的记忆，科学家追踪了一种“遗传标记”，以揭示神经元的活动。研究人员最终发现，神经细胞中CREB的数量影响着该细胞是否被用于存储记忆。Silva说，“如果细胞中的CREB含量较低，那么它保存记忆的可能性就小；反之，该细胞更有可能存储记忆。”
这一最新研究成果对于人类具有深远的意义。Silva表示，“通过人工控制大脑神经细胞中CREB蛋白的含量，我们将能够决定大脑存储记忆的位置。这种方法有望被用于保护阿尔海默症等大脑疾病患者的记忆。我们有可能引导记忆从大脑濒死区域的病态神经细胞进入其他位置的健康神经细胞。”
原始出处:
Science 20 April 2007:
Vol. 316. no. 5823, pp. 457 - 460
DOI: 10.1126/science.1139438
Reports
Neuronal Competition and Selection During Memory Formation
Jin-Hee Han,1,2,3* Steven A. Kushner,4,5,6* Adelaide P. Yiu,1,3 Christy J. Cole,1,2 Anna Matynia,4 Robert A. Brown,4 Rachael L. Neve,7 John F. Guzowski,8 Alcino J. Silva,4 Sheena A. Josselyn1,2,3
Competition between neurons is necessary for refining neural circuits during development and may be important for selecting the neurons that participate in encoding memories in the adult brain. To examine neuronal competition during memory formation, we conducted experiments with mice in which we manipulated the function of CREB (adenosine 3',5'-monophosphate response element–binding protein) in subsets of neurons. Changes in CREB function influenced the probability that individual lateral amygdala neurons were recruited into a fear memory trace. Our results suggest a competitive model underlying memory formation, in which eligible neurons are selected to participate in a memory trace as a function of their relative CREB activity at the time of learning.
1 Program in Neurosciences and Mental Health, Hospital for Sick Children, 555 University Avenue, Toronto, ontario M5G 1X8, Canada.
2 Department of Physiology, University of Toronto, Toronto, ontario M5S 1A8, Canada.
3 Institute of Medical Sciences, University of Toronto, Toronto, ontario M5S 1A8, Canada.
4 Departments of Neurobiology, Psychology, and Psychiatry, and Brain Research Institute, Gonda Building, 695 Young Drive South, University of California, Los Angeles, CA 90095, USA.
5 Department of Psychiatry, Columbia University, New York, NY 10032, USA.
6 New York State Psychiatric Institute, New York, NY 10032, USA.
7 Molecular Neurogenetics Laboratory, Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, MA 02478, USA.
8 Neurobiology and Behavior, School of Biological Sciences, University of California, Irvine, CA 92697, USA.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: sheena.josselyn@sickkids.ca
