Ongoing Activity in Temporally Coherent Networks Predicts Intra-Subject Fluctuation of Response Time to Sporadic Executive Control Demands

Can ongoing fMRI BOLD signals predict fluctuations in swiftness of a person’s response to sporadic cognitive demands? This is an important issue because it clarifies whether intrinsic brain dynamics, for which spatio-temporal patterns are expressed as temporally coherent networks (TCNs), have effects not only on sensory or motor processes, but also on cognitive processes. Predictivity has been affirmed, although to a limited extent. Expecting a predictive effect on executive performance for a wider range of TCNs constituting the cingulo-opercular, fronto-parietal, and default mode networks, we conducted an fMRI study using a version of the color–word Stroop task that was specifically designed to put a higher load on executive control, with the aim of making its fluctuations more detectable. We explored the relationships between the fluctuations in ongoing pre-trial activity in TCNs and the task response time (RT). The results revealed the existence of TCNs in which fluctuations in activity several seconds before the onset of the trial predicted RT fluctuations for the subsequent trial. These TCNs were distributed in the cingulo-opercular and fronto-parietal networks, as well as in perceptual and motor networks. Our results suggest that intrinsic brain dynamics in these networks constitute “cognitive readiness,” which plays an active role especially in situations where information for anticipatory attention control is unavailable. Fluctuations in these networks lead to fluctuations in executive control performance.

持续的功能磁共振成像（functional magnetic resonance imaging，fMRI）血氧水平依赖（blood oxygen level-dependent，BOLD）信号能否预测个体对突发认知任务的反应速度波动？这一问题具有重要学术意义，因为它可阐明内在脑动力学——其时空模式以时间连贯网络（temporally coherent networks，TCNs）的形式呈现——不仅对感觉或运动过程产生影响，还可作用于认知过程。尽管已有研究证实了该信号具备预测能力，但预测范围仍较为有限。鉴于扣带回-岛叶网络、额顶网络及默认模式网络等更广泛的时间连贯网络可能对执行功能表现具有预测效应，本研究采用专门设计的色词斯特鲁普（color–word Stroop）任务开展功能磁共振成像研究，该任务通过提升执行控制负荷以使反应时波动更易被检测。本研究旨在探索试前阶段时间连贯网络的活动波动与任务反应时（reaction time，RT）之间的关联。研究结果显示，存在一类时间连贯网络，其在试次开始前数秒的活动波动可预测后续试次的反应时波动。这类时间连贯网络分布于扣带回-岛叶网络、额顶网络、感知网络及运动网络中。本研究结果表明，上述网络的内在脑动力学构成了"认知准备状态（cognitive readiness）"，尤其在无法获取预期注意控制信息的情境中发挥积极作用，此类网络的活动波动会直接导致执行控制表现的波动。