Computational protocol: Regional Homogeneity of Intrinsic Brain Activity in Happy and Unhappy Individuals

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Protocol publication

[…] Data were preprocessed using DPARSF (Data Processing Assistant and Resting-State FMRI, version 2.2) with the following steps: (1) removing the first ten volumes to account for the T1 equilibrium effect, leaving 230 volumes for final analysis; (2) slice timing correction; (3) motion correction by realigning images to the first volume then to the mean functional image; (4) segmenting T1 images into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF); (5) regressing out 27 nuisance covariates (including signals from WM, CSF, global signal, and Friston 24 motion parameters) to reduce the potential effects of physiological processes and motion. The Friston 24-parameter model (i.e., 6 head motion parameters, 6 head motion parameters one time point before, and the 12 corresponding squared items) was used to regress out head motion effects based on recent work showing that higher-order models were more effective in removing head motion effects , . The linear trends were also removed; (6) spatially normalizing the functional images to the Montreal Neurological Institute (MNI) space using the standard EPI template in SPM8 and resampling the images at a resolution of 3 mm×3 mm×3 mm; and (7) temporally band-pass filtering (0.01Resting state fMRI data analysis toolkit, version 1.8) . Specifically, the Kendall's coefficient of concordance (KCC) of each voxel was calculated with its nearest neighbors (26 voxels) in a voxel-wise analysis. The formula for calculating the KCC value has been expounded in a previous study . To reduce the influence of individual variations in the KCC value, standardization of ReHo maps were done by dividing the KCC of a given voxel by the averaged KCC of the whole brain. Then, the standardized ReHo maps were smoothed with a Gaussian kernel of 4 mm full-width at half-maximum to reduce noise. […]

Pipeline specifications

Software tools DPABI, SPM, REST
Application Functional magnetic resonance imaging
Organisms Homo sapiens