Li Xingfeng, Kehoe Elizabeth G, McGinnity Thomas Martin, Coyle Damien, Bokde Arun L W
1 Perinatal Imaging Department, St Thomas' Hospital, King's College London , London, United Kingdom .
Brain Connect. 2015 Feb;5(1):60-7. doi: 10.1089/brain.2014.0249. Epub 2014 Dec 29.
It is known that the default mode network (DMN) may be modulated by a cognitive task and by performance level. Changes in the DMN have been examined by investigating resting-state activation levels, but there have been very few studies examining the modulation of effective connectivity of the DMN during a task in healthy older subjects. In this study, the authors examined how effective connectivity changed in the DMN between rest and during a memory task. The authors also investigated whether there was any relationship between effective connectivity modulation in the DMN and memory performance, to establish whether variations in cognitive performance are related to neural network effective connectivity, either at rest or during task performance. Twenty-eight healthy older participants underwent a resting-state functional magnetic resonance imaging scan and an emotional face-name encoding task. Effective connectivity analyses were performed on the DMN to examine the effective connectivity modulation in these two different conditions. During the resting state, there was strong self-influence in the regions of the DMN, while the main regions with statistically significant cross-regional effective connectivity were the posterior cingulate cortex (PCC) and the hippocampus (HP). During the memory task, the self-influence effective connectivities remained statistically significant across the DMN, and there were statistically significant effective connectivities from the PCC, HP, amygdala (AM), and parahippocampal region to other DMN regions. The authors found that effective connectivities from PCC, HP, and AM (in both resting state and during task) were linearly correlated to memory performance. The results suggest that superior memory ability in this older cohort was associated with effective connectivity both at rest and during the memory task of three DMN regions, which are also known to be important for memory function.
已知默认模式网络（DMN）可能会受到认知任务和表现水平的调节。通过研究静息态激活水平来考察DMN的变化，但很少有研究考察健康老年受试者在任务期间DMN有效连接性的调节情况。在本研究中，作者考察了DMN在静息和记忆任务期间有效连接性是如何变化的。作者还研究了DMN中有效连接性调节与记忆表现之间是否存在任何关系，以确定认知表现的变化是否与静息或任务执行期间神经网络的有效连接性有关。28名健康老年参与者接受了静息态功能磁共振成像扫描和情绪面孔-名字编码任务。对DMN进行有效连接性分析，以考察这两种不同条件下的有效连接性调节。在静息状态下，DMN区域存在较强的自我影响，而具有统计学显著跨区域有效连接性的主要区域是后扣带回皮质（PCC）和海马体（HP）。在记忆任务期间，DMN中的自我影响有效连接性在统计上仍然显著，并且从PCC、HP、杏仁核（AM）和海马旁区域到其他DMN区域存在统计学显著的有效连接性。作者发现，来自PCC、HP和AM的有效连接性（在静息状态和任务期间）与记忆表现呈线性相关。结果表明，该老年队列中卓越的记忆能力与三个DMN区域在静息和记忆任务期间的有效连接性有关，而这三个区域也已知对记忆功能很重要。
