Abstract
One of the most fundamental features of the human brain is its ability to detect and attend to salient goal-relevant events in a flexible manner. The salience network (SN), anchored in the anterior insula and the dorsal anterior cingulate cortex, plays a crucial role in this process through rapid detection of goal-relevant events and facilitation of access to appropriate cognitive resources. Here, we leverage the subsecond resolution of large multisession fMRI datasets from the Human Connectome Project and apply novel graph-theoretical techniques to investigate the dynamic spatiotemporal organization of the SN. We show that the large-scale brain dynamics of the SN are characterized by several distinctive and robust properties. First, the SN demonstrated the highest levels of flexibility in time-varying connectivity with other brain networks, including the frontoparietal network (FPN), the cingulate–opercular network (CON), and the ventral and dorsal attention networks (VAN and DAN). Second, dynamic functional interactions of the SN were among the most spatially varied in the brain. Third, SN nodes maintained a consistently high level of network centrality over time, indicating that this network is a hub for facilitating flexible cross-network interactions. Fourth, time-varying connectivity profiles of the SN were distinct from all other prefrontal control systems. Fifth, temporal flexibility of the SN uniquely predicted individual differences in cognitive flexibility. Importantly, each of these results was also observed in a second retest dataset, demonstrating the robustness of our findings. Our study provides fundamental new insights into the distinct dynamic functional architecture of the SN and demonstrates how this network is uniquely positioned to facilitate interactions with multiple functional systems and thereby support a wide range of cognitive processes in the human brain.
Highlights
The human brain is a complex system capable of supporting a wide range of adaptive goal-relevant behaviors
We used a set of 264 brain nodes widely distributed across the entire brain and encompassing key large-scale brain networks, including salience network (SN), cingulate–opercular network (CON), frontoparietal network (FPN), dorsal attention network (DAN), ventral attention network (VAN), subcortical, default mode network (DMN), memory systems, visual, auditory, sensory-motor networks as well as the cerebellum (Fig 1A)
Dynamic connectivity analysis revealed that the SN together with subcortical nodes have the highest level of temporal flexibility in the brain, significantly higher than FPN, CON, DAN, and VAN
Summary
The human brain is a complex system capable of supporting a wide range of adaptive goal-relevant behaviors. These behaviors are thought to be supported by the intrinsic functional architecture of large-scale functional systems that constrain and support diverse cognitive processes in a stable, yet flexible, manner [1,2,3]. The anterior insula (AI) and dorsal anterior cingulate cortex (dACC) nodes of the SN are among the most commonly activated regions in human neuroimaging studies [5,11,12], pointing to the ubiquitous involvement of this network in cognition. Identification of the dynamic spatiotemporal properties of the SN is an important open question in systems and clinical human neuroscience
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