He has worked in the field of movement disorders for 30 years, focusing primarily on the underlying brain mechanisms which mediate the symptoms of parkinsonism and dyskinesias. He is author of over 150 peer-reviewed research papers, book chapters and reviews on brain research, mostly in the field of movement disorders. Professor Crossman's group have made significant contributions to elucidation of the abnormal brain pathways and mechanisms by which movement disorders are mediated, which has paved the way to the introduction of new treatment strategies. One of their most significant achievements has been the discovery of the importance of the subthalamic nucleus (STN) in generating parkinsonian symptoms, which led to the introduction of surgical manipulation of the STN in Parkinson's disease. Professor Crossman is also author of a popular medical student textbook on brain anatomy and is currently editing the nervous system section for the next edition of Gray's Anatomy.