Lateralized Structural Connectivity Of The Salience Network

Objective:Based on the human connectome project(HCP)and two Chinese cohorts,the present study aimed to detect the structural connectivity profile between the frontoinsular cortex(FIC)and dorsal anterior cingulate cortex(dACC)using the diffusive magnetic resonance imaging(dMRI).Furthermore,to validate the reliability of the dACC-FIC structural connectivity,we attempted to illuminate the association between normal aging and the fractional anisotropy(FA)of dACC-rFIC connectivity,which may help to better understand the functional and structural properties of the SN in normal human brain.Subjects and Methods:This study included 100 normal,young adults from the HCP consortium,50 healthy,unrelated Chinese young adults and 112 healthy Chinese elder.Firstly,based on the coordinates of three SN hubs derived from a prior study,the functional connectivity(FC)was respectively calculated between each ROI and the whole brain voxels using HCP resting-state fMRI data,and conjunction analyses were carried out to define the SN.Then,the deterministic fiber tracking was performed to construct the structural connectivity between FIC and dACC in each hemisphere in dMRI data of 100 HCP subjects and 50 Chinese young adults.Finally,a partial correlation analysis between the age and FA values of the dACC-rFIC connectivity was carried out to observe the alteration of the right-side FIC-dACC structural connectivity in normal aging.Results:1.FC between ROIs and whole brain voxels and conjunction analysis identified the brain areas that had positive FCs within the SN,including the dACC,bilateral FIC,temporal parietal junction(TPJ)and anterior middle frontal gyri(MFG).2.The extent and strength of functional connectivity in the SN showed a right-lateralization.Meanwhile,based on the dACC and FIC masks from the fore-mentioned step,the same right-lateralization was also found in the dACC-FIC structural connectivity using the deterministic fiber tracking method3.The dACC-FIC structural connectivity profile:these fibers were projected from the subcortical white matter of the dACC,then crossed the anterior corona radiate,and finally terminated at the same side FIC region.Notably,the fibers sprouted two branches in the FIC:one branch terminated at the frontal operculum and the other at the anterior insula via the external capsule4.With age growing,the FA of the right dACC-FIC showed a significant trend of reduction.Conclusion:The SN,as a neural network discovered from the fMRI,indeed has the anatomical basis to support its functional property.The functional and structural connectivity of the SN exist a significant right-lateralization between two core hubs,the dACC and FIC.Additionally,the structural impairment of dACC-rFIC connectivity occurs in the normal aging.