Fig. 6: Image processing steps.

a All participants underwent a structural brain MRI scan including T1, T2, and diffusion weighted images (DTI = diffusion tensor imaging) with 43 volumes. b Lesions were manually drawn on each participant’s T2-weighted image. c A chimeric T1 image was created for each participant where the stroke area was replaced by the mirrored equivalent of the intact, right hemisphere (healed T1, lower panel)⁷⁴. The healed T1 was transformed into the Montreal Neurological Institute 152 (MNI152) standard space⁷⁵. The stroke lesion was co-registered to the healed T1 standard space. Each participant’s T1-weighted image was segmented into gray matter regions of interest with the Johns Hopkins University anatomic atlas; the segmentation maps were registered into DTI space. d Probabilistic tractography was performed, and tracts were estimated between all pairs of gray matter regions. The procedure resulted in a 100 \(\times\) 100 adjacency matrix where values represented the (corrected) number of probabilistic streamlines between two regions (heatmap in lower panel). Of note, the connectomes did not include the healed tissue. For better visualization, the color bars of the heatmaps represent log values, and the white matter connections in brain space (upper panel) are based on deterministic instead of probabilistic tractography.