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. 2015 Apr 29;35(17):6822–6835. doi: 10.1523/JNEUROSCI.3709-14.2015

Figure 1.

Figure 1.

Flowchart for the analyses of behavioral and imaging data. A, Mapping behavior with self-obtained tracts: (1) Reconstruction of white fibers in the whole brain (b) by using DTI deterministic tractography on the FA (fractional anisotropy) map (a) for healthy participants. (2) Filtering out the WM fibers connecting every pair of seed spheres (c) and identifying the tract mask of each pair seeds (d) consisted of all the voxels reaching the threshold with AlphaSim correction (corrected cluster level: p < 0.05; voxel level: sign test p < 0.05). (3–4) Inputting the tract mask into the lesion map (e) or the FA map (f) of each patient to calculate the percentage of voxels with lesion (g, number of voxels with lesion divided by total number of voxels on the tract) or mean FA value (h, averaging the FA values of all voxels in the tract), respectively. (5–6) Obtaining the tool-relevant tracts in separate analyses, through correlating the standardized “t” behavioral scores with lesion percentages (i) or the mean FA values (j) across the 86 patients, partialling out the total lesion volume. (7) Obtaining the tracts important for tool processing, namely, those with significant effects in both the lesion analysis and the mean FA analysis. B, Validation with voxel-based lesion-symptom mapping analyses: (1) Calculating VLSM analysis map (c) by comparing the standardized “t” behavioral scores between damaged and intact patients on each voxel of the lesion map (a), with total lesion volume as a covariate. (2) Calculating VFSM analysis map (d) by correlating the standardized “t” behavioral scores with FA values of each voxel of the FA map (b) across the 86 patients, with total lesion volume as a covariate. (3) Obtaining the tool-related voxels (e), which had significant effects in both the VLSM and VFSM analyses. (4) Extracting the tool-related tracts (g), through overlaying the tool-related voxels onto JHU WM tractography atlas (Hua et al., 2008), which includes 20 major WM tracts of the human brain. The figures were displayed using the BrainNet Viewer (Xia et al., 2013) software package.