title: Toward reliable characterization of functional homogeneity in the human brain: preprocessing, scan duration, imaging resolution and computational space.
abstract: While researchers have extensively characterized functional connectivity between brain regions, the characterization of functional homogeneity within a region of the brain connectome is in early stages of development. Several functional homogeneity measures were proposed previously, among which regional homogeneity (ReHo) was most widely used as a measure to characterize functional homogeneity of resting state fMRI (R-fMRI) signals within a small region (Zang et al., 2004). Despite a burgeoning literature on ReHo in the field of neuroimaging brain disorders, its test-retest (TRT) reliability remains unestablished. Using two sets of public R-fMRI TRT data, we systematically evaluated the ReHo's TRT reliability and further investigated the various factors influencing its reliability and found: 1) nuisance (head motion, white matter, and cerebrospinal fluid) correction of R-fMRI time series can significantly improve the TRT reliability of ReHo while additional removal of global brain signal reduces its reliability, 2) spatial smoothing of R-fMRI time series artificially enhances ReHo intensity and influences its reliability, 3) surface-based R-fMRI computation largely improves the TRT reliability of ReHo, 4) a scan duration of 5 min can achieve reliable estimates of ReHo, and 5) fast sampling rates of R-fMRI dramatically increase the reliability of ReHo. Inspired by these findings and seeking a highly reliable approach to exploratory analysis of the human functional connectome, we established an R-fMRI pipeline to conduct ReHo computations in both 3-dimensions (volume) and 2-dimensions (surface).
authors.affiliation: Laboratory for Functional Connectome and Development, Key Laboratory of Behavioral Science, Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. zuoxn@psych.ac.cn
authors.forename: Xi-Nian
authors.initials: XN
authors.lastname: Zuo
authors.forename: Ting
authors.initials: T
authors.lastname: Xu
authors.forename: Lili
authors.initials: L
authors.lastname: Jiang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Yang
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Cao
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Zang
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Castellanos
authors.forename: Michael P
authors.initials: MP
authors.lastname: Milham
mesh_terms: D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D009434:Neural Pathways / Q000033:anatomy & histology* / Q000502:physiology*; D015203:Reproducibility of Results