Figure 3. Flowchart of steps involved in computing FC scores.

The pipeline for computing the FC score within the left LN in a single patient using real data; the full procedure is described in detail in our previous study.¹⁹ In the first step (A and E), for each patient, we computed an ROI-based (e.g., left IFG) voxelwise FC map for each ROI of each network. These maps were generated by computing the Pearson correlation coefficient r between the ROI time course and the time courses from all other brain voxels. The correlation coefficients were Fisher z-transformed prior to further analyses, thereby generating z(r) maps. Orange-yellow colors indicate voxels with positive FC with the ROI; blue-cyan colors indicate negative FC. In step 2 (B–C and F–G), for each patient, we applied to each ROI-based FC map a mask (derived from the young controls and retaining voxels with z[r] > 0.3) of the corresponding network either to the same hemisphere (e.g., left LN_mask) or in the opposite hemisphere (not shown). Therefore, for a given ROI in the left hemisphere (e.g., left IFG), we obtained 2 FC masked maps, the former retaining the voxels exhibiting FC between the ROI and the left LN (C and G), the latter including voxels showing the interhemispheric FC with the right LN (not shown). Similarly, for an ROI in the right hemisphere, we obtained a map indicating the voxels in the same hemisphere (right) and one map in the opposite hemisphere (left). These computations yielded for each ROI 4 masked FC maps: left ROI/left mask, left ROI/right mask, right ROI/left mask, and right ROI/right mask. Then, for each masked FC map, we averaged the z(r) values of the voxels comprised within the borders of the network map obtaining an ROI-to-network FC score (D and H). To compute the left-hemisphere LN FC (left LN FC), we calculated the ROI-to-network scores of the maps seeded in the left hemisphere and masked with left-hemisphere mask (D and H). The final left LN FC score was obtained for each patient by averaging all the ROI-to-network FC scores (I). The same computation was applied on the left and right ROIs of the cingulo-opercular (not shown), yielding a left and right intrahemispheric FC score for each network. We then computed the interhemispheric FC score by averaging the z(r) values of the voxels in the right hemisphere derived from the left ROI-based FC masked maps and the values of the voxels in the left hemisphere derived from the right ROI-based FC masked maps. The final FC score for the cingulo-opercular network was obtained by averaging the FC values of the left and right intrahemispheric FC as well as the interhemispheric FC. FC = functional connectivity; IFG = inferior frontal gyrus; LH = left hemisphere; LN = language network; RH = right hemisphere; ROI = region of interest; STG = superior temporal gyrus.