摘要 : 麦基尔大学等处的科学家通过研究揭示了控制大脑记忆的神经回路及动态学机制，该机制同时也是海马体发挥重要作用的基本元件。相关文章发表于2014年8月31日的《Nature Neuroscience》杂志上。

完整的实验显示subicular失活和CA3区的变化

早在2009年研究者们就开发了一种特殊的方法，即海马体形成的体外制备法;如今研究者们在小鼠机体内也成功实现了上述海马体的制备方法，海马体中和记忆相关的活性流并不是单向的。

记忆可以形成我们的核心身份，尽管如此，记忆的产生及提取也是我们无法理解的一种现象，研究者们围绕学习和记忆相关的神经回路已经开展了大量的研究，因为人们会因此而患各种疾病，比如阿尔兹海默氏症等。

近些年来，研究者Sylvain Williams及其同事才开始着手重点研究大脑神经回路的动态学机制，研究者表示，记忆编码和提取的过程需要海马体中成千上万个神经元的活化，尽管如此，研究者们对于该过程所涉及的神经回路依然知之甚少。

揭示海马体中神经元的行为或许可以帮助科学家们能够深入理解和阿尔兹海默氏症等神经变性疾病相关疾病中神经回路的异常表现机制，只有鉴别出海马体中的相关神经元回路或许才可以帮助理解记忆的效应机制，而对这些神经回路复杂动力学的理解也将帮助研究人员揭示阿尔兹海默氏症患者大脑的早期改变，为开发新型的靶向疗法将提供更多的研究思路。

原文摘要：

Reversal of theta rhythm flow through intact hippocampal circuits

Jesse Jackson, Bénédicte Amilhon, Romain Goutagny, Jean-Bastien Bott, Frédéric Manseau, Christian Kortleven, Steven L Bressler & Sylvain Williams

Activity flow through the hippocampus is thought to arise exclusively from unidirectional excitatory synaptic signaling from CA3 to CA1 to the subiculum. Theta rhythms are important for hippocampal synchronization during episodic memory processing; thus, it is assumed that theta rhythms follow these excitatory feedforward circuits. To the contrary, we found that theta rhythms generated in the rat subiculum flowed backward to actively modulate spike timing and local network rhythms in CA1 and CA3. This reversed signaling involved GABAergic mechanisms. However, when hippocampal circuits were physically limited to a lamellar slab, CA3 outputs synchronized CA1 and the subiculum using excitatory mechanisms, as predicted by classic hippocampal models. Finally, analysis of in vivo recordings revealed that this reversed theta flow was most prominent during REM sleep. These data demonstrate that communication between CA3, CA1 and the subiculum is not exclusively unidirectional or excitatory and that reversed inhibitory theta signaling also contributes to intrahippocampal synchrony.