Assessing Topographic Structural Connectivity of the Human Basal Ganglia and Thalamus

Irtiza A. Gilani; Kader K. Oguz; Huseyin Boyaci; Katja Doerschner

This classification analysis was performed in a voxel-based approach in order to identify the connectivity based topographic subdivisions within each subcortical structure and to quantify the relative frequency of connections between these structures. This approach resulted in structural subdivisions of a specified ROI based on the specific pathways originating from that ROI. Seed classification was performed to identify the connectivity pathways between each seed ROI and the rest of the ROIs that were regarded as targets. This process resulted in a version of a seed ROI mask, called resulting mask, which demonstrated the likelihood of connectivity of each voxel in that ROI with the rest of the subcortical and cortical ROIs. The voxel values of the resulting mask showed the number of tracts originating from the seed ROI and reaching the target ROI successfully. Since the total number of tracts that were generated from each seed voxel was 5000, dividing each voxel value in the resulting mask by 5000 gives the relative frequency of connectivity at that spatial location or voxel.