Fig. 4.

Eigenvector Centrality (EC) differences between both treatment states when comparing levodopa medication (PRE_ON) with both left and right STN DBS using a weighted contrast (POST_ON = POST_{ON_right} + POST_{ON_left}). The top row shows a color-coded map of EC differences with the contrast POST_ON−PRE_ON using all three approaches of EC computation (‘abs’, ‘add’ and ‘pos’). Interestingly, there is a large overlap of EC computed with all three approaches (color-coded in yellow) indicating that EC differences are dominated by positive correlations between BOLD time courses. The middle row shows EC differences in the OFF-conditions using the contrast POST_OFF−PRE_OFF (see also middle row of Fig. 2). The bottom row shows the interaction between both factors PRE/POST and OFF/ON using the interaction contrast including the difference of difference (POST_ON−PRE_ON)−(POST_OFF−PRE_OFF). Significant clusters were obtained with p < 0.05 using correction of multiple comparisons with the false discovery rate (FDR) approach (see Table 3 including coordinates, cluster sizes, and statistical values for the ‘add’ approach).