Submaximal Exercise Provokes Increased Activation of the Anterior Default Mode Network During the Resting State as a Biomarker of Postexertional Malaise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Figures

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  FIGURE 1. Hierarchical clustering heatmaps. Time series data identified 29 nodes in seven resting state networks as independent components (IC) using templates in FSLnets. Heatmap overlay is red-blue, where red signifies positive and blue signifies negative correlations, respectively. Clade color corresponds to parent resting state network. Purple clade = Default Mode Network (DMN). Green clade = Frontal Parietal Network (FPN). Yellow clade = Sensorimotor Network (SMN). Orange clade = Dorsal Attention Network (DAN). Blue clade = Salience Network (SAL). Red clade = Subcortical Network (SUB). Aqua clade = Visual Network (VIS). The insert figures show representative FSL probability maps to localize each node.

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  FIGURE 2. Default mode network nodes. Node amplitude strengths were compared by ANOVA and Tukey Honest Significant Difference for differences between groups and by paired Student’s t-test for exercise effects between days within groups. DMN_PCC (red in top figure on right) and DMN_Prec (magenta in middle figure on right) were equivalent between control and CFS and between preexercise and postexercise scans. In contrast, exercise had significant effects on the anterior node in the DMN_mPFC (green in the bottom figure on the right). Node amplitude strengths were equivalent for CFS and control preexercise. Exercise caused a significant decrease in control (∗p = 0.0029 by paired test), but a significant increase for CFS (∗∗p = 0.00036 by paired test). As a result of the dynamic changes, CFS had significantly higher signal than control postexercise (line above error bars, p = 0.000078). Mean ± SD.

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  FIGURE 3. Pearson correlation matrices. Age and gender regressed BOLD amplitude data were correlated for (A) sedentary control preexercise, (B) sedentary control postexercise, (C) CFS preexercise, and (D) CFS postexercise. Correlations are shown with R > 0.5 (light yellow), R > 0.6 (yellow), R > 0.7 (orange), R > 0.8 (red), and R > 0.9 (dark red) that were all p < 0.001 uncorrected. There were no significant negative correlations. Networks and nodes were highlighted in color on the right: DMN cyan, FPN green, DAN orange, SMN gray, SAL blue, SUB pink, and VIS yellow.