Fig 3.

Selected images illustrating the subthalamic nucleus (6) in the basal forebrain. Coronal, sagittal, and axial images show the subthalamic nucleus as a biconvex hypointense structure nestled along the medial margin of the internal capsule (26). B, The darkest portion of the internal capsule just anterior to the subthalamic nucleus represents the Edinger comb system (77) containing the pallidosubthalamic, pallidonigral, and nigrostriatal tracts. The small white circle represents the potential DBS electrode tip placement site (Table 2) in the inferior portion of the zona incerta (asterisk), which corresponds with a better therapeutic profile according to Plaha et al.²²