The highly influential tri-network model proposed by Menon integrates 3 key intrinsic brain networks — the central executive network (CEN), the salience network (SN), and the default mode network (DMN), into a single cohesive model underlying normal behaviour and cognition. A large body of evidence suggests that abnormal intra- and inter- network connectivity between these three networks underlies the various behavioural and cognitive dysfunctions observed in patients with neuropsychiatric conditions such as PTSD and depression. An important prediction of the tri-network model is that the DMN and CEN networks are anti-correlated under the control of the SN, such that if a task engages one of the two, the SN inhibits the activation of the other. To date most of the evidence surrounding the functions of these three core networks comes from either resting state analyses or in the context of a single task with respect to rest. Few studies have investigated multiple tasks simultaneously or characterized the dynamics of task switching. Hence, a careful investigation of the temporal dynamics of network activity during task switching is warranted. To accomplish this we collected fMRI data from 14 participants that dynamically switched between a 2-back working memory task and an autobiographical memory retrieval task, designed to activate the CEN, DMN and the SN. The fMRI data were used to 1. identify nodes and sub-networks within the three major networks involved in task-linked dynamic network switching, 2. characterize the temporal pattern of activation of these nodes and sub-networks, and finally 3. investigate the causal influence that these nodes and sub-networks exerted on each other. Using a combination of multivariate neuroimaging analyses, timecourse analyses and multivariate Granger causality measures to study the tri-network dynamics, the current study found that the SN co-activates with the task-relevant network, providing a mechanistic insight into SN-mediated network selection in the context of explicit tasks. Our findings also indicate active involvement of the posterior insula and some medial temporal nodes in task-linked functions of the SN and DMN, warranting their inclusion as network nodes in future studies of the tri-network model. These results add to the growing body of evidence showing the complex interplay of CEN, DMN and SN nodes and sub-networks required for adequate task-switching, characterizing a normative pattern of task-linked network dynamics within the context of Menon’s tri-network model.

Menon提出的极具影响力的三网络模型将3个主要的内在大脑网络-中央执行网络（CEN），显着网络（SN）和默认模式网络（DMN）集成到一个基于正常行为和认识。大量证据表明，在患有PTSD和抑郁症等神经精神疾病的患者中，这三个网络之间的内部和内部网络连接异常，是各种行为和认知功能障碍的基础。三网模型的一个重要预测是，DMN和CEN网络在SN的控制下是反相关的，因此，如果一项任务参与了两者之一，则SN会阻止另一项的激活。迄今为止，围绕这三个核心网络功能的大多数证据来自静息状态分析或关于静息的单一任务。很少有研究同时研究多个任务或表征任务切换的动态性。因此，必须仔细研究任务切换期间网络活动的时间动态。为此，我们从14名参与者那里收集了fMRI数据，这些参与者在2后退工作记忆任务和自传记忆检索任务之间动态切换，旨在激活CEN，DMN和SN。fMRI数据用于1.识别与任务相关的动态网络交换所涉及的三个主要网络中的节点和子网，2.表征这些节点和子网激活的时间模式，最终3.研究这些节点和子网相互施加的因果关系。通过将多元神经影像分析，时程分析和多元Granger因果关系度量相结合，研究三网络动力学，当前研究发现SN与任务相关网络共同激活，从而为SN介导的网络选择提供了一种机械的见解。在明确的任务范围内。我们的研究结果还表明，后岛和一些颞内侧节点积极参与了SN和DMN的任务链接功能，从而保证了它们在三网模型的未来研究中被列为网络节点。这些结果增加了越来越多的证据，显示出足够的任务切换所需的CEN，DMN和SN节点和子网之间的复杂相互作用，