Professor Dr. K.L. Leenders is a clinical neurologist who trained at the University of Amsterdam and who became board licensed in 1980 in The Netherlands. From 1982 until 1988 he worked at the Hammersmith Hospital London as Senior Registrar and participated in the PET research program at the MRC Cyclotron Unit. He has been concerned with movement disorders since 1982 as a visiting neurologist at the The Neurological Institute Queen Square, London (Prof D Marsden). From 1989 until 1998 he was head of the movement disorder clinic of the Neurology Department at the Zurich University Hospital (Switzerland). At the same time he has been responsible for running a research program concerning movement disorders using PET radiotracer imaging techniques at the Paul Scherrer Institute, the national physics institute in Switzerland. Since 1998 he has taken the position of professor of neurology at the Department of Neurology at the University Medical Centre Groningen (UMCG), The Netherlands. One of the main themes of his research program involves PET radiotracer studies of metabolic and neurotransmitter changes in Parkinson's disease, Huntington's disease and dystonia. During the last few years fMRI studies have increasingly become an important part of his program. Collaborations exist with many groups on a national and international basis.