Park Hyojin, Lee Dong Soo, Kang Eunjoo, Kang Hyejin, Hahm Jarang, Kim June Sic, Chung Chun Kee, Jensen Ole
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, 110-744, Korea; Institute of Radiation Medicine, Medical Research Center, Seoul National University, Seoul, 110-744, Korea; Interdisciplinary Program in Cognitive Science, Seoul National University, Seoul, 151-742, Korea.
Hum Brain Mapp. 2014 Aug;35(8):3972-87. doi: 10.1002/hbm.22452. Epub 2014 Feb 12.
In our daily lives, we are confronted with a large amount of information. Because only a small fraction can be encoded in long-term memory, the brain must rely on powerful mechanisms to filter out irrelevant information. To understand the neuronal mechanisms underlying the gating of information into long-term memory, we employed a paradigm where the encoding was directed by a "Remember" or a "No-Remember" cue. We found that posterior alpha activity increased prior to the "No-Remember" stimuli, whereas it decreased prior to the "Remember" stimuli. The sources were localized in the parietal cortex included in the dorsal attention network. Subjects with a larger cue-modulation of the alpha activity had better memory for the to-be-remembered items. Interestingly, alpha activity reflecting successful inhibition following the "No-Remember" cue was observed in the frontal midline structures suggesting preparatory inhibition was mediated by anterior parts of the dorsal attention network. During the presentation of the memory items, there was more gamma activity for the "Remember" compared to the "No-Remember" items in the same regions. Importantly, the anticipatory alpha power during cue predicted the gamma power during item. Our findings suggest that top-down controlled alpha activity reflects attentional inhibition of sensory processing in the dorsal attention network, which then finally gates information to long-term memory. This gating is achieved by inhibiting the processing of visual information reflected by neuronal synchronization in the gamma band. In conclusion, the functional architecture revealed by region-specific changes in the alpha activity reflects attentional modulation which has consequences for long-term memory encoding.
在我们的日常生活中，我们面临着大量的信息。由于只有一小部分信息能够被编码到长期记忆中，大脑必须依靠强大的机制来过滤掉无关信息。为了理解信息进入长期记忆的门控背后的神经元机制，我们采用了一种范式，其中编码由“记住”或“不记住”提示引导。我们发现，在“不记住”刺激之前，后阿尔法活动增加，而在“记住”刺激之前，后阿尔法活动减少。其来源定位于背侧注意网络中的顶叶皮层。阿尔法活动的提示调制较大的受试者对要记住的项目有更好的记忆。有趣的是，在额中线结构中观察到了反映“不记住”提示后成功抑制的阿尔法活动，这表明准备性抑制是由背侧注意网络的前部介导的。在记忆项目呈现期间，与“不记住”项目相比，相同区域中“记住”项目的伽马活动更多。重要的是，提示期间的预期阿尔法功率预测了项目期间的伽马功率。我们的研究结果表明，自上而下控制的阿尔法活动反映了背侧注意网络中感觉处理的注意力抑制，这最终将信息门控到长期记忆中。这种门控是通过抑制伽马波段中神经元同步所反映的视觉信息处理来实现的。总之，阿尔法活动区域特异性变化所揭示的功能结构反映了注意力调制，这对长期记忆编码有影响。
