Singapore Institute for Neurotechnology (SINAPSE), Centre for Life Science, National University of Singapore, Singapore.
Center of Cognitive Neuroscience, Neuroscience & Behavioral Disorders Program, Duke-NUS Graduate Medical School, Singapore.
Neuroimage. 2017 May 15;152:19-30. doi: 10.1016/j.neuroimage.2017.02.084. Epub 2017 Feb 28.
Although rest breaks are commonly administered as a countermeasure to reduce mental fatigue and boost cognitive performance, the effects of taking a break on behavior are not consistent. Moreover, our understanding of the underlying neural mechanisms of rest breaks and how they modulate mental fatigue is still rudimentary. In this study, we investigated the effects of receiving a rest break on the topological properties of brain connectivity networks via a two-session experimental paradigm, in which one session comprised four successive blocks of a mentally demanding visual selective attention task (No-rest session), whereas the other contained a rest break between the second and third task blocks (Rest session). Functional brain networks were constructed using resting-state functional MRI data recorded from 20 healthy adults before and after the performance of the task blocks. Behaviorally, subjects displayed robust time-on-task (TOT) declines, as reflected by increasingly slower reaction time as the test progressed and lower post-task self-reported ratings of engagement. However, we did not find a significant effect on task performance due to administering a mid-task break. Compared to pre-task measurements, post-task functional brain networks demonstrated an overall decrease of optimal small-world properties together with lower global efficiency. Specifically, we found TOT-related reduced nodal efficiency in brain regions that mainly resided in the subcortical areas. More interestingly, a significant block-by-session interaction was revealed in local efficiency, attributing to a significant post-task decline in No-rest session and a preserved local efficiency when a mid-task break opportunity was introduced in the Rest session. Taken together, these findings augment our understanding of how the resting brain reorganizes following the accumulation of prolonged task, suggest dissociable processes between the neural mechanisms of fatigue and recovery, and provide some of the first quantitative insights into the cognitive neuroscience of work and rest.
虽然休息被普遍作为一种减少精神疲劳和提高认知表现的对策，但休息对行为的影响并不一致。此外，我们对休息时大脑连接网络拓扑性质的基本神经机制及其如何调节精神疲劳的理解还很初步。在这项研究中，我们通过一个两阶段实验范式，调查了在接受休息时对大脑连接网络拓扑性质的影响。在一个阶段中，包括连续四个需要精神集中的视觉选择性注意任务的任务块（无休息阶段），而在另一个阶段中，在第二个和第三个任务块之间包含一个休息（休息阶段）。使用从 20 名健康成年人在执行任务块前后记录的静息状态功能磁共振成像数据构建功能大脑网络。行为上，随着测试的进行，被试的反应时间逐渐变慢，任务后自我报告的参与度评分也降低，表现出明显的随时间推移（TOT）下降。然而，由于在任务中途安排了休息，我们并没有发现对任务表现有显著影响。与任务前测量相比，任务后功能大脑网络表现出整体优化小世界属性的降低以及全局效率的降低。具体来说，我们发现 TOT 相关的节点效率降低主要发生在皮质下区域。更有趣的是，局部效率显示出显著的块-阶段交互作用，这归因于无休息阶段的任务后显著下降，以及在休息阶段提供中间休息机会时保留的局部效率。总之，这些发现增加了我们对大脑在长时间任务后如何重新组织的理解，表明疲劳和恢复的神经机制之间存在可分离的过程，并为工作和休息的认知神经科学提供了一些首批定量见解。
