Figure 3.

Comparison of mean amplitude of low frequency fluctuation (mALFF) with and without masks by paired t-tests. (A) mALFF activities in brain regions were significantly different with and without face masks. (B) Comparison of power spectrum of mALFF in different brain regions. The posterior cingulate cortex (PCC, MNI coordinates: x = 0 mm, y =−45 mm, z = 27 mm, radius 6 mm) and medial prefrontal cortex (MPFC, MNI coordinates: x = 0 mm, y = 63 mm, z = 13 mm, radius 6 mm) were selected as seed points for functional connectivity analysis. The results of the one-sample t-test with and without face masks showed that the PCC was positively correlated with the precuneus, middle temporal lobe, inferior temporal lobe, medial prefrontal lobe, and orbital inferior frontal gyrus and negatively correlated with the superior marginal gyrus, middle cingulate cortex, rolandic operculum, precentral lobe, postcentral lobe, and fusiform gyrus. The MPFC was positively correlated with the precuneus, posterior cingulate gyrus, supplementary motor cortex, angular gyrus, middle temporal lobe, and inferior temporal lobe and negatively correlated with the superior marginal gyrus, middle cingulate cortex, precentral lobe, postcentral lobe, middle occipital cortex, middle frontal gyrus, and inferior frontal gyrus of the triangle (p < 0.05, Figure 4).