2012年11月25日 讯 /生物谷BIOON/ --当机体进入深睡眠状态时，大脑海马体会向大脑皮层发送信息，并且改变其可塑性，这或许会转移个体近期获得性的长期记忆。那么大脑具体是如何完成此项工作的，近日来自马普研究所的研究人员开发出了一种多元的方法，名为“神经事件触发的功能性磁共振成像”技术（NET-fMRI），使用此项技术，研究者就可以对麻醉、苏醒甚至是活动中的猴子进行扫描检测其大脑活性的情况，相关研究刊登于国际杂志Nature上。
这种新型技术使用了多重接触电极同大脑功能性的磁共振成像相结合，来绘制特殊神经事件中处于激活状态的神经元的遍布网络。此项研究中，研究者首次使用这种NET-fMRI技术来对猴子进行检测，检测其大脑海马体振荡（形成波纹）活性区域的活性是处于增加状态还是降低状态。海马体的波纹产生一般发生于深睡眠状态，并且可以通过电生理学方法检测得到。使用颅内场电位记录的方法，研究者阐述了短期内大脑海马体波纹不定期循环发生和可再生的大脑皮质激活密切相关。
更有意思的是，大脑内激活结构的抑制可以干扰海马体和大脑皮层之间的交流对话。下丘脑活性的抑制可以减小和感觉过程相关的信号。当基底核受到抑制后，大脑桥区域以及小脑皮层会相抵和记忆系统相关的信号，比如处于程序性学习阶段下等情况。
研究发现为理解记忆力的大型组织架构的形成提供了一定基础，从神经元网络的激活到认知能力的出现，研究者都可以使用功能性的成像技术或传统的单一神经元记录的方法进行描述。感觉能力、注意力、学习能力以及记忆力都可以使用诸如NET-fMRI技术来进行研究分析，研究这些能力形成的神经分子机制对于理解其能力的形成以及发挥至关重要。（生物谷Bioon.com）
编译自：Neural Interaction in Silence: Neurophysiologists Study Widespread Networks of Neurons Responsible for Memory
doi:10.1038/nature11618
PMC:
PMID:
Hippocampal–cortical interaction during periods of subcortical silence
N. K. Logothetis, O. Eschenko, Y. Murayama, M. Augath, T. Steudel, H. C. Evrard, M. Besserve & A. Oeltermann
Hippocampal ripples, episodic high-frequency field-potential oscillations primarily occurring during sleep and calmness, have been described in mice, rats, rabbits, monkeys and humans, and so far they have been associated with retention of previously acquired awake experience. Although hippocampal ripples have been studied in detail using neurophysiological methods, the global effects of ripples on the entire brain remain elusive, primarily owing to a lack of methodologies permitting concurrent hippocampal recordings and whole-brain activity mapping. By combining electrophysiological recordings in hippocampus with ripple-triggered functional magnetic resonance imaging, here we show that most of the cerebral cortex is selectively activated during the ripples, whereas most diencephalic, midbrain and brainstem regions are strongly and consistently inhibited. Analysis of regional temporal response patterns indicates that thalamic activity suppression precedes the hippocampal population burst, which itself is temporally bounded by massive activations of association and primary cortical areas. These findings suggest that during off-line memory consolidation, synergistic thalamocortical activity may be orchestrating a privileged interaction state between hippocampus and cortex by silencing the output of subcortical centres involved in sensory processing or potentially mediating procedural learning. Such a mechanism would cause minimal interference, enabling consolidation of hippocampus-dependent memory.
