Fig. 6: The strength and stability of interhemispheric functional connectivity.

A A significant negative correction is observed between the FC of homotopic regions and the heterogeneity of their projections (r = −0.614, ±95% C.I. = [−0.7955, −0.3322], p < 0.001). B Homotopic FC is not significantly correlated with the strength of direct connections between homotopic regions (r = 0.218, ±95% C.I. = [−0.1475,0.5315], p = 0.238). C FC strength of the three types of connections across all brain states: intrahemispheric-heterotopic (intra-hete), interhemispheric-heterotopic (inter-hete), and homotopic connections (homo) (N = 19, the number of sessions). The left column presents the results of FC from all anatomically connected regions (Tukey-HSD two-side test for multiple comparisons, intra-hete vs inter-hete: p = 0.0485, intra-hete vs homo: p = 0, inter-hete vs homo: p = 0), which have more intrahemispheric-heterotopic connections than interhemispheric-heterotopic connections. The right column compares interhemispheric-heterotopic connections with their corresponding intrahemispheric-heterotopic counterparts (Tukey-HSD two-side test for multiple comparisons, intra-hete vs inter-hete: p = 0.0001). The FC strength comparison in each brain state is presented in Supplementary Fig. 7C. D FC variability of the three types of connections. Variability is estimated by salience values of PLS analysis across brain states (N = 1000, the number of Bootstrap sampling). Left panel: Tukey-HSD two-side test for multiple comparisons, (intra-hete vs inter-hete: p = 0, intra-hete vs homo: p = 0, inter-hete vs homo: p = 0). Right panel: Tukey-HSD two-side test for multiple comparisons, (intra-hete vs inter-hete: p = 0). E, F Comparison between the interhemispheric-heterotopic connections and their intrahemispheric counterparts in FC strength and stability across all brain states. Results for each brain state are shown in Supplementary Fig. 9D, E. Note that stability is represented by the inverse of variability. “only intra-hete”, only intrahemispheric heterotopic anatomical connections exist between two brain regions; “intra-hete > inter-hete”, the intrahemispheric heterotopic connection has a higher value (strength or stability) than the interhemispheric heterotopic one, and vice versa for “inter-hete > intra-hete”. Comparison between interhemispheric-heterotopic connections and the homotopic connection of each brain region in FC strength (G) and stability (H). The median value (white point), the 25th percentile, the 75th percentile, the maximum value, and the minimum value of all violin plots are provided in Supplementary Data 8. Source data are provided as a Source Data file.