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...tion was chosen for ease of implementation, and the results are not expected to depart markedly from those using canonical correlation and other similar methods (e.g., Regional Homogeneity or ”ReHo“: =-=Zang et al., 2004-=-; Paakki et al., 2010; Shukla et al., 2010; see also Jiang et al., 2013). GCOR preprocessing model and analyses The +GCOR model, as discussed above in the section Basic Model + GCOR, involves the same...

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...roup differences in terms of AM (these data are not further reported here). Regional homogeneity (ReHo) is a measure of similarity or homogeneity of the time series in a local neighborhood of voxels (=-=Zang et al. 2004-=-). It is defined formally as Kendall’s coefficient of concordance: ReHo P ðRi RiÞ2 K2ðn3 nÞ=12 P ðRiÞ2 nðRÞ2 K2ðn3 nÞ=12 ; ð3Þ here, Ri Pk j1 rij is the sum rank of the ith time point and rij...

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...rent features (the predictor variables used for classification) that can be extracted from resting state fMRI data. Three of the most frequently used features are the regional homogeneity maps (ReHo, =-=Zang et al., 2004-=-), fractional amplitude of low frequency fluctuations (ALFF) maps (fALFF, Zou et al., 2008), and independent component maps (ICA, Smith et al., 2009). In the current study, we present a systematic eva...

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...d. Although this approach can find altered FC between two brain areas in the early blind individuals, it cannot answer which area’s activity is being altered. However, the analysis of the regional homogeneity (ReHo) of the resting-state blood oxygen level-dependent (BOLD) signals can partly answer the question. ReHo is proposed based on the hypothesis that the brain activity would more likely occur as clusters rather than as a single voxel, thus Kendall’s coefficient of concordance (KCC) was used to evaluate the similarity between the time series of a given voxel and its nearest neighborhoods [15]. The pattern of resting-state brain activities obtained by the ReHo method is very similar to that observed by PET in healthy individuals, which indicates that ReHo is a promising measurement for the resting-state local brain activities. Subsequently, ReHo has been successfully applied to study a variety of neurological and psychiatric diseases [16–18]. In this study, we used the ReHo approach to investigate changes in the brain spontaneous activity in the early blind individuals. We hypothesize that the altered ReHo should be found in occipital areas in the early blind individuals, as earlie...

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...cross the healthy group and the ADHD patients, which include both local measures such as fractional amplitude of low frequency fluctuations (fALFF) (Zou et al., 2008) and regional homogeneity (ReHo) (=-=Zang et al., 2004-=-), and the global characteristics like the functional connectivity derived from various definitions. A brain-wide association study (BWAS) (Ji et al., 2012) and feature integration are performed to ex...

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...h requirement of the experimental information. Typically, as brain activations evoked by various stimuli are not manifested as a single voxel, but rather as groups of tens to hundreds of voxels [22], =-=[23]-=-, [34]. The correlations between each activated voxel and its neighboring activated voxels should 0018-9294/$20.00 © 2006 IEEE CHEN et al.: INTEGRATED NEIGHBORHOOD CORRELATION AND HIERARCHICAL CLUSTER...

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...nctional connectivity (FC) analysis, which measures the correlation coefficients of all brain areas with a predefined region, have often been used. ReHo was first used to analyze imaging data by Zang =-=[11]-=-. In this method, Kendall’s coefficient concordance (KCC) was used to measure the similarity of a time series of a given voxel to its nearest voxels in a voxel-wise manner based on the postulation tha...

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...e first is manual labeling by experts using their domain knowledge. The second is asdata-driven clustering of ROIs from the brain image itself. For instance, the ReHo (regionalshomogeneity) algorithm =-=[11]-=- has been used to identify regional homogeneous regions as ROIs.sThe third is to predefine ROIs in a template brain, and warp them back to the individual spacesusing image registration [12]. Lastly, R...

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...e series. It cansbe considered complementary to the model-driven method,sand its major advantage is the ability to detect unpredictedshemodynamic responses that the model-driven methodsfails to reveal=-=[41]-=-. While functional connectivity measures thestemporal synchronization of distinct brain regions, ReHosmeasures the local synchronization. We used the ReHosapproach to analyze the fMRI data in normal a...