Recent investigations on cebus monkeys have also shown that the subthalamic nucleus (STN) has a disynaptic projection to the cerebellar cortex via the pontine nuclei (PN).13 Similar data have recently been found in humans, using diffusion tensor imaging (DTI).14,15 These data have stimulated new research directed at investigating the role of Cer and BG in functions typically associated with cortical areas (e.g., action understanding7,16,17), and the role of cerebellar and cortical areas in impairments typically associated with BG, such as Tourette’s syndrome,18 dystonia,19 and PD.8,20–23. The gene discussed is CBLN1; the disease is Parkinson disease.