Sun Yu, Lim Julian, Kwok Kenneth, Bezerianos Anastasios
Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Sciences, National University of Singapore, Singapore.
Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Sciences, National University of Singapore, Singapore; Temasek Laboratories, National University of Singapore, Singapore; Department of Psychology, National University of Singapore, Singapore.
Brain Cogn. 2014 Mar;85:220-30. doi: 10.1016/j.bandc.2013.12.011. Epub 2014 Jan 21.
Changes in functional connectivity across mental states can provide richer information about human cognition than simpler univariate approaches. Here, we applied a graph theoretical approach to analyze such changes in the lower alpha (8-10 Hz) band of EEG data from 26 subjects undergoing a mentally-demanding test of sustained attention: the Psychomotor Vigilance Test. Behavior and connectivity maps were compared between the first and last 5 min of the task. Reaction times were significantly slower in the final minutes of the task, showing a clear time-on-task effect. A significant increase was observed in weighted characteristic path length, a measure of the efficiency of information transfer within the cortical network. This increase was correlated with reaction time change. Functional connectivity patterns were also estimated on the cortical surface via source localization of cortical activities in 26 predefined regions of interest. Increased characteristic path length was revealed, providing further support for the presence of a reshaped global topology in cortical connectivity networks under fatigue state. Additional analysis showed an asymmetrical pattern of connectivity (right>left) in fronto-parietal regions associated with sustained attention, supporting the right-lateralization of this function. Interestingly, in the fatigue state, significance decreases were observed in left, but not right fronto-parietal connectivity. Our results indicate that functional network organization can change over relatively short time scales with mental fatigue, and that decreased connectivity has a meaningful relationship with individual difference in behavior and performance.
与简单的单变量方法相比，跨心理状态的功能连接变化能够提供有关人类认知的更丰富信息。在此，我们应用一种图论方法来分析26名受试者在进行一项需要集中注意力的持续性注意力测试（即精神运动警觉性测试）时脑电图（EEG）数据的较低阿尔法波段（8 - 10赫兹）中的此类变化。对任务的前5分钟和后5分钟的行为及连接图谱进行了比较。在任务的最后几分钟，反应时间显著变慢，显示出明显的任务持续时间效应。加权特征路径长度（一种衡量皮质网络内信息传递效率的指标）显著增加。这种增加与反应时间变化相关。还通过对26个预定义感兴趣区域的皮质活动进行源定位，在皮质表面估计了功能连接模式。结果显示特征路径长度增加，进一步支持了疲劳状态下皮质连接网络中存在重塑的全局拓扑结构。额外的分析表明，与持续注意力相关的额顶叶区域存在不对称的连接模式（右侧>左侧），支持了该功能的右侧化。有趣的是，在疲劳状态下，左侧额顶叶连接性出现显著下降，而右侧则未出现。我们的结果表明，功能网络组织会随着精神疲劳在相对较短的时间尺度上发生变化，并且连接性降低与行为和表现的个体差异存在有意义的关联。
