Subjects: Psychology >> Medical Psychology Subjects: Biology >> Neurobiology submitted time 2018-04-02
Abstract： Introduction Autism spectrum disorder (ASD) is a neurodevelopmental disease with unknown etiology but high incidence. The objective biomarkers of ASD are urgently awaited to be developed using neuroimaging method including resting-state fMRI (R-fMRI). However, the majority of current R-fMRI studies only examined the static features of brain activity in ASD patients, but neglected the dynamic aspects especially for regional metrics. Furthermore, the concordance of the dynamic regional indices was reported imbedded in human intrinsic brain activity, while it’s abnormality in ASD is largely unknown. Methods In this study, we analyzed R-fMRI data of 480 ASD male patients and 539 healthy male controls (HC) gathered from ASD public database (ABIDE/ABIDE II). We used sliding window method to calculate the dynamics of mainstream regional indices of R-fMRI (amplitude of low frequency fluctuations (ALFF), fractional ALFF (fALFF), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VMHC), degree centrality (DC) and the correlation with global signal (GSCorr)) and generated the SD statistic maps of these six dynamic regional indices. We performed z-standardization and smoothing on the SD statistic maps. After that, two-sample t-test between the SD statistic maps of ASD group and HC group was performed. We also calculated the concordance of dynamic regional indices for each time point, which is the Kendall's coefficient of the ALFF, ReHo, DC, GSCorr and VMHC maps across voxels. Two-sample t-test between the SD and mean of concordance time series of ASD group and HC group was performed. Results We found a significant increase in the dynamics of ALFF and DC in the lateral frontal cortices in ASD patients as compared to HCs. Dorsal lateral frontal cortex (dlPFC) is a critical brain area for cognitive control and execution network. The abnormal activities in dlPFC indicate the disruption of control execution system and the impairment of relevant cognitive function. In the visual related brain areas, the dynamics of ALFF, DC and ReHo showed a decrease in fusiform gyrus, calcarine and lingual gyrus in ASD patients. Recent studies have indicated that the abnormal face processing in children with autism may be related with the impairment in social cognition of them. The deficits in face information processing of ASD patients may stem from the inflexible intrinsic brain activity in visual processing brain area (especially in fusiform gyrus). After further examining the concordance among these dynamic indices, the mean and SD of concordance of patients with ASD was found to be significantly lower than that of the HCs, demonstrating that the ASD patients’ inferior integration ability for different aspects of brain functions. Conclusion These findings suggest that there exists abnormality in dynamics of spontaneous brain activity and its integration in ASD patients. Dynamic R-fMRI regional indices and the concordance of them could be efficient neuroimaging biomarkers for ASD.
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