FIGURE 2.

Distinct global signal in ASD patients may have implicit impact on interhemispheric rsfMRI connectivity. (A) Correlation matrices showing the inter-subject similarity of interhemispheric rsfMRI connectivity pattern for three datasets collected at different sites. The data from the first two sites, i.e., CAL and PBG show a big difference between the ASD and control groups with controls showing much higher cross-subject similarities. (B) Conditions for rsfMRI experiments. The first two sites collected rsfMRI data under sleep-conducive eyes-closed condition. (C) Histograms showing the distribution of all pairwise rsfMRI connectivity. In the first two datasets, the control groups show overall stronger rsfMRI connectivity compared with the ASD groups. However, this difference was not observed in the third dataset. (D) RsfMRI connectivity maps with respect to a seed region at the posterior cingulate cortex (PCC) showing the DMN network. In the first two datasets, the control groups show larger spatially non-specific correlations compared with the ASD groups, presumably due to a larger global signal. (E) Standard deviation of the global rsfMRI signal. The control groups of the first two datasets are characterized by significantly larger global signal than the ASD groups, whereas the global signal is smaller and not different in the two groups for the third dataset. ^∗0.01 < p < 0.05.