Abstract
Aberrant topological properties of small-world human brain networks in patients with schizophrenia (SZ) have been documented in previous neuroimaging studies. Aberrant functional network connectivity (FNC, temporal relationships among independent component time courses) has also been found in SZ by a previous resting state functional magnetic resonance imaging (fMRI) study. However, no study has yet determined if topological properties of FNC are also altered in SZ. In this study, small-world network metrics of FNC during the resting state were examined in both healthy controls (HCs) and SZ subjects. FMRI data were obtained from 19 HCs and 19 SZ. Brain images were decomposed into independent components (ICs) by group independent component analysis (ICA). FNC maps were constructed via a partial correlation analysis of ICA time courses. A set of undirected graphs were built by thresholding the FNC maps and the small-world network metrics of these maps were evaluated. Our results demonstrated significantly altered topological properties of FNC in SZ relative to controls. In addition, topological measures of many ICs involving frontal, parietal, occipital and cerebellar areas were altered in SZ relative to controls. Specifically, topological measures of whole network and specific components in SZ were correlated with scores on the negative symptom scale of the Positive and Negative Symptom Scale (PANSS). These findings suggest that aberrant architecture of small-world brain topology in SZ consists of ICA temporally coherent brain networks.
Highlights
Cognitive dysfunction has been viewed as the core of schizophrenia, a chronic psychotic disorder [1,2,3,4,5]
If significant difference was found for any brain component, Pearson linear correlation coefficients were used to examine the relationship between topological properties of that brain component and Positive and Negative Symptom Scale (PANSS) scores in the SZ group
The finding that topological properties were altered in SZ and that several metrics were significantly correlated with negative PANSS scores in SZ provides further evidence for aberrant functional network connectivity (FNC) associated with this disease [33]
Summary
Cognitive dysfunction has been viewed as the core of schizophrenia, a chronic psychotic disorder [1,2,3,4,5]. ICA, which was developed to solve problems similar to the ‘‘cocktail party’’ scenario in which individual voices must be resolved from microphone recordings of many people speaking simultaneously [19,24], has typically been applied to fMRI data by determining a set of maximally spatially independent brain networks each with associated time courses [25,26,27] This approach is useful to examine brain activity during resting state in both healthy controls (HCs) and various patient groups [28,29,30,31,32]. The topological properties of these FNC relationships have not yet been studied
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