Figure 2. Reduced inter-hemispheric homotopic functional connectivity in AD and aMCI.

Left: After controlling for age, sex, race, handedness, and head motion, the three groups showed significant differences in the inter-hemispheric homotopic functional connectivity (i.e., VMHC) in the MFG, PreC, PoCG and ROL (regions highlighted in orange color) using ANOVA (color bar represents F-values). Middle: The AD patients had decreased VMHC in the MFG and temporal-parietal regions (extending to the insula) (regions highlighted in blue color) compared to aMCI patients. Right: The AD patients had decreased VMHC in more widespread brain regions, including the MFG, temporal-parietal and occipital regions (extending to the PCC, insula and hippocampus), than the controls. The blue color bars indicate t-values of each comparison. No differences in VMHC were detected between aMCI and controls. All results were reported at a height threshold of p < 0.01 and cluster threshold of p < 0.05 with GRF correction. Abbreviations: AD, Alzheimer’s disease; aMCI, amnestic mild cognitive impairment; Ctrl, Control; MFG, Middle frontal gyrus; ROL, Rolandic; PoCG, Postcentral gyrus; PreC, Precuneus; PCC, Posterior cingulate cortex; VMHC, voxel mirrored homotopic connectivity; GRF, Gaussian random field.