Selection procedure selection of neuronal tracts. (A) Selection of cortico-striatal and thalamo-cortical tracts. A tract was considered to intersect a nucleus (striatum or thalamus) if at least three tract points were inside the nucleus. For the cortex, only intersections with <2 mm from the low band of cortical area were considered. (B) Selection of tracts among basal ganglia structures and thalamus. A tract was considered for the analysis, if it intersected the nucleus at least on the three points. Black crosses represent the tracts that were rejected.