Age-Related Decline in the Variation of Dynamic Functional Connectivity: A Resting State Analysis

Figure 1. Illustration of the dynamic functional connectivity (FC) variation patterns within groups. Pictures (A,D) show the one-sample t-test results of senior and young null groups with phase randomization processed data (FDR p-value < 0.05; actual p-value < 0.0010); Pictures (B,E) show the one-sample t-test results of senior and young groups with the original data (FDR p-value < 0.05; actual p-value < 0.0011); Pictures (C,F) show two-sample t-test results between the original and phase randomized data within the senior and young groups (FDR p-value < 0.05; actual p-value < 0.0008). Red indicates a higher-than-average level in the one-sample t-test and a higher-than-null group in the two-sample t-test.

Figure 2. Illustration of the two-sample t-test results of the static FC compared between the senior and young groups. Pictures (A,C) depict the connections level and the network averaging level, respectively; Picture (B) is a 3D view of the results shown in picture (A) (constructed using the BrainNet Viewer). Red indicates an increase in the senior group; blue indicates a decrease in the senior group. The significant level is a p-value < 0.001.

Figure 3. Illustration of the two-sample t-test results of the dynamic FC variation (FCV) between the senior and young groups. Pictures (A,C) depict the connections level and network averaging level, respectively; Picture (B) is a 3D view of the results shown in picture (A) (constructed using the BrainNet Viewer). Red indicates an increase in the senior group; blue indicates a decrease in the senior group. The significance level is a p-value < 0.001.

Figure 4. Illustration of the two-sample t-test results of the energy percentage in the low fluctuation frequency band compared between the senior and young groups. Pictures (A,C) depict the connections level and the network averaging level, respectively; Picture (B) is a 3D view of the results shown in picture (A) (constructed using the BrainNet Viewer). Red indicates an increase in the senior group; blue indicates a decrease in the senior group. The significance level is a p-value < 0.001.

Figure 5. Illustration of the difference (absolute value of the difference) between the mean dynamic FC and the static FC. The results of five networks are individually averaged for all connections, which are plotted as gray curves; the red curves represent the means of all subjects from both groups.

Figure 6. Illustration of the frequency spectrum, which varied with the sliding window length, for all five networks of one typical subject. The results of five networks were calculated from the individually averaged FC sequence of the within-network connections.