The Contribution Of The Salience Network Study On Healthy Young Adults’ Fluid Reasoning

Objective:We combined VBM analysis of structural MRI data and ReHo analysis of resting-state fMRI data to investigate neural correlates of fluid reasoning capacity as measured by RSPM in a large sample of healthy young adults.Subjects and Methods:A total of324right-handed healthy young adults were recruited in this study. In the present study, the RSPM score was used to assess individual capability of fluid reasoning by using the Raven’s Standard Progressive Matrices (Raven1976). Resting-state fMRI scan and sagittal structural images were all collected using a GE3.0T Signa HDX scanner. During the scanning, all subjects were explicitly instructed to keep their eyes closed, relax, as motionless as possible and think of nothing. All preprocessing steps were carried out using the statistical parametric mapping (SPM8, http://www.fil.ion.ucl.ac.uk/spm) based on Matlab. The preprocessing of high resolution structural data including segmentation of gray and white matter, spatial normalization and smooth with a4mm full width at half maximum, while the preprocessing of rs-fMRI data including slice timing, realignment, spatial normalization to the MNI, resampling to to2×2×2mm3cubic voxels, a band-pass frequency filter (0.01-0.08Hz, to reduce low-frequency drift and high-frequency noise) and smoothed with a4mm full width at half maximum. Finally, individual mReHo maps were generated by calculating Kendall’s coefficient concordance (KCC) within a gray matter mask in a voxel-wise way by the DPARSFA software. Voxel-based partial correlation analyses were separately carried out to test correlations between the RSPM scores and the GMVs or ReHo values while age and gender were entered as covariates of no interest and multiple comparisons were statistically corrected by Monte Carlo simulation. Finally the corrected statistical parameter mapping was overlapped onto MNI standard template and the coordinate, size and peak t values of each significant cluster were recorded.Results:After the affected factors (head motion, behavioral performance and machine noise) were ruled out, for VBM analyses,297healthy participants were finally included, while for ReHo analysis,284subjects were finally involved.After correction for multiple comparisons, RSPM scores were positively correlated with the GMVs in the right fronto-insular cortex (FIC) and the left dorsal anterior cingulate cortex (ACC) of the salience network, the bilateral temporal poles, orbitofrontal cortices (OFC), occipital lobes, and the left sensorimotor cortex and parahippocampal and fusiform gyri (FG). There is no brain area whose GMV was negatively correlated with the RSPM scores in these subjects.Under the same threshold as the VBM analysis, RSPM scores were positively correlated with ReHo values in the right FIC of the salience network, the right middle frontal gyrus and temporal pole, and the left fusiform (FG) and parahippocampal gyri. In contrast, RSPM scores were negatively correlated with ReHo values in the bilateral sensorimotor cortex, the posterior cingulate cortex, the precuneus and the right inferior parietal lobule of the default-mode network (DMN).Conclusion:1. Fluid reasoning capacity is related to gray matter volumes of the salience network;2. Fluid reasoning capacity is related to regional homogeneity of the salience network;3. Fluid reasoning capacity is also related to brain areas of other functional networks;4. The salience network plays a crucial contribution to fluid reasoning capacity.