Brain Struct Funct (2008) 212:443–463 DOI 10.1007/s00429-007-0170-0 O R I G I N A L A R T I C L E Human pallidothalamic and cerebellothalamic tracts: anatomical basis for functional stereotactic neurosurgery Marc N. Gallay Æ Daniel Jeanmonod Æ Jian Liu Æ Anne Morel Received: 7 September 2007 / Accepted: 20 December 2007 / Published online: 10 January 2008 The Author(s) 2008 Abstract Anatomical knowledge of the structures to be targeted and of the circuitry involved is crucial in stereo- tactic functional neurosurgery. The present study was undertaken in the context of surgical treatment of motor disorders such as essential tremor (ET) and Parkinson’s disease (PD) to precisely determine the course and three- dimensional stereotactic localisation of the cerebellotha- lamic and pallidothalamic tracts in the human brain. The course of the ﬁbre tracts to the thalamus was traced in the subthalamic region using multiple staining procedures and their entrance into the thalamus determined according to our atlas of the human thalamus and basal ganglia [Morel (2007) Stereotactic atlas of the human thalamus and basal ganglia. Informa Healthcare Inc., New York]. Stereotactic three-dimensional coordinates were determined by sec- tioning thalamic and basal ganglia blocks parallel to stereotactic planes and, in two cases, by correlation with magnetic resonance images (MRI) from the same brains prior to sectioning. The major contributions of this study are to provide: (1) evidence that the bulks of the cerebel- lothalamic and pallidothalamic tracts are clearly separated up to their thalamic entrance, (2) stereotactic maps of the M. N. Gallay D. Jeanmonod J. Liu A. Morel (&) Laboratory for Functional Neurosurgery, Neurosurgery Clinic, University Hospital Zu¨rich, Sternwartstrasse 6, 8091 Zurich, Switzerland e-mail: anne.morel@usz.ch Present Address: J. Liu Department of Physiology and Pathophysiology, School of Medicine, Xi’an Jiaotong University, 710061 Xian, People’s Republic of China two tracts in the subthalamic region, (3) the possibility to discriminate between different subthalamic ﬁbre tracts on the basis of immunohistochemical stainings, (4) correla- tions of histologically identiﬁed ﬁbre tracts with high- resolution MRI, and (5) evaluation of the interindividual variability of the ﬁbre systems in the subthalamic region. This study should provide an important basis for accurate stereotactic neurosurgical targeting of the subthalamic region in motor disorders such as PD and ET. Keywords Basal ganglia Thalamus Essential tremor Parkinson’s disease Motor disorders Abbreviations ac al Acb AChE Amg ap AV B bic CaBP Cd CeM CB CR CL Cl CM CTT fct Anterior commissure Ansa lenticularis Accumbens nucleus Acethylcholinesterase Amygdala Ansa peduncularis Anteroventral nucleus Basal nucleus of Meynert Brachium of the inferior colliculus Calcium-binding proteins Caudate nucleus Central medial nucleus Calbindin D-28K Calretinin Central lateral nucleus Claustrum Centre me´dian nucleus (or centromedian) Cerebellothalamic tractotomy Fasciculus cerebello-thalamicus 123