Optogenetic stimulation of anterior insular cortex neurons in male rats reveals causal mechanisms underlying suppression of the default mode network by the salience network

• Published in: Nature communications Vol. 14; no. 1; p. 866
• Main Authors: Menon, Vinod, Cerri, Domenic, Lee, Byeongwook, Yuan, Rui, Lee, Sung-Ho, Shih, Yen-Yu Ian
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.02.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 59/36; 631/378/116/2393; 631/378/3920; Animals; Brain; Brain architecture; Brain Mapping; Cognition; Cognitive ability; Computational neuroscience; Cortex (insular); Decoupling; Default Mode Network; Functional magnetic resonance imaging; Humanities and Social Sciences; Insular Cortex; Magnetic Resonance Imaging; Male; Males; multidisciplinary; Nerve Net - physiology; Network switching; Neural networks; Neurons; Optogenetics; Rats; Salience; Science; Science (multidisciplinary); Stimulation; Switching
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-36616-8

The salience network (SN) and default mode network (DMN) play a crucial role in cognitive function. The SN, anchored in the anterior insular cortex (AI), has been hypothesized to modulate DMN activity during stimulus-driven cognition. However, the causal neural mechanisms underlying changes in DMN activity and its functional connectivity with the SN are poorly understood. Here we combine feedforward optogenetic stimulation with fMRI and computational modeling to dissect the causal role of AI neurons in dynamic functional interactions between SN and DMN nodes in the male rat brain. Optogenetic stimulation of Chronos-expressing AI neurons suppressed DMN activity, and decreased AI-DMN and intra-DMN functional connectivity. Our findings demonstrate that feedforward optogenetic stimulation of AI neurons induces dynamic suppression and decoupling of the DMN and elucidates previously unknown features of rodent brain network organization. Our study advances foundational knowledge of causal mechanisms underlying dynamic cross-network interactions and brain network switching. The salience network has been hypothesised to modulate default mode network activity during stimulus-driven cognition. Here, the authors show that in rats, stimulation of the anterior insular cortex, a key node of the salience network, suppresses the default mode network and decouples these networks, providing in vivo evidence of a causal role of the anterior insular cortex in brain network switching.