**5. The Salience Network (SN)**

*5.1. Overview of SN*

The SN is the brain network that detects and filters external stimuli and recruits relevant functional networks [202]. This network is essential for detecting and integrating emotional and sensory stimuli, allocating attention, and switching between internally directed cognition and externally directed cognition [203]. The SN's hub is the ventral anterior insula [204], and the SN also includes nodes in the amygdala, hypothalamus, ventral striatum, and thalamus [203]. The SN was suggested to be functionally subdivided into dorsal and ventral components that support cognitive and emotional controls, respectively [205]. The key SN regions activated during cognitive tasks consist of dorsal components: the dorsal anterior cingulate cortex and the right anterior insula [205,206]. For example, the SN engages the ECN and disengages the DMN during cognitive tasks but does the opposite during rest [207]. Regarding cognitive function, the extent of dissociation between the ECN and SN is related to cognitive task performance [208]. Additionally, the structural connectivity shown by diffusion tensor image analysis is also positively correlated with SN intraconnectivity (right anterior insula to dorsal anterior cingulate cortex) and deactivation of the DMN during tasks, which is in turn related to cognitive function [209].
