PMC4485173_01
Pipeline for generating the connectivity matrices. We collected pre and post diffusion tensor imaging (DTI) data from a patient and then generated the whole-brain tractography for all voxels (bottom left). In addition to the 90 cortical and subcortical regions in the automated anatomical labeling (AAL) template, we incorporated the subthalamic nucleus (STN), based on the binarised version of a probabilistic mask (Forstmann et al.,). This resulted in a total of 92 cortical and subcortical regions (46 per hemisphere). We reconstructed the whole-brain connectivity matrix between these 92 brain regions using the methods described in van Hartevelt et al.. Due to the electrode artifact in the left hemisphere (see bottom left), in the subsequent analyses we only used the right hemisphere connectivity matrices.
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F1
Secondly, the edges, or connections between nodes, were estimated using probabilistic tractography (Figure 1). Due to the artifact of the DBS lead in the left hemisphere in the postoperative DTI data (see bottom left of Figure 1), only the sub-network corresponding to the right hemisphere was considered. In other words, we only used the 46 x 46 matrix corresponding to the right hemisphere (without inter-hemispheric connections) and not the full 92 x 92 connectivity matrix as shown in Figure 1.