Dissociable salience networks in the macaque brain anchored in right anterior insula
J Zhang, Adrian Touroutoglou, Eliza Bliss‐Moreau, Dante Mantini, Wim Vanduffel, Dan Dickerson, Lisa Feldman Barrett · Lirias · 2014
Salience network (Seeley et al., 2007) is a resting state network heavily involved in affective processing and includes major nodes such as amygdala, anterior insula (AI) and anterior cingulate cortex (ACC). Research on human salience network has demonstrated two separable networks anchored by ventral and dorsal AI (vAI and dAI), respectively implicated in attention and affective experience (Touroutoglou et al., 2012). In monkeys, despite a burgeoning number of resting state studies (Mantini et al., 2013; Belcher et al., 2013; Hutchison et al., 2011), it is still not known whether there is a salience network. We used a hypothesis-driven seed-based approach to investigate whether salience network exists in the monkey brain and has similar dorsal and ventral extents, which may give us insights into how affect is experienced by monkeys. Subjects were 4 rhesus monkeys (1 female, 4-6kg, 4-7y.o.) (Mantini et al., 2013). Each subject underwent twenty 10-min resting state scans in a 3T Siemens scanner, during which they sat in a sphinx position while continuously fixating a point on a blank screen. fMRI data were slice time corrected, motion corrected, linearly detrended, coregistered to the anatomical image, spatially normalized to F99 atlas space, and smoothed with a 2mm fwhm Gaussian kernel. Regions of interest (ROIs) were generated as 2mm-radius spheres centered on right frontal insula (FI), vAI and dAI coordinates homologous to the respective human seeds (Seeley et al., 2007; Touroutoglou et al., 2012). At subject level, whole-brain connectivity was calculated for the average time course from each ROI and then converted to z-scores; at group level, correlation maps were produced by fixed-effect analysis (Mantini et al., 2011). Right FI seed reveals a salience network consisting of dorsal ACC, bilateral AI and amygdalae. Right vAI and dAI have distinct connectivity patterns. The vAI seed is preferentially connected to dorsal ACC, pregenual ACC, ventral AI and bilateral amygdalae, closely resembling human vAI network. The dAI seed is preferentially connected to posterior cingulate, dorsal and ventral AI, putamen, and dorsolateral prefrontal cortex, lacking some parietal targets in human dAI network.To our knowledge, this is the first study that clearly demonstrates the existence of salience network in the macaque brain at 3T. Importantly, we identified two distinct networks anchored by vAI and dAI seeds. Furthermore, while the vAI-seeded network closely resembles the human vAI network, the dAI-seeded network exhibits some different characteristics than the human dAI network. Our findings have implications for understanding affective experience in monkeys.