Functional imaging of the motor system

Functional imaging methods such as positron emission tomography (PET) and m agnetic resonance tomography (FMRI) enable non-invasive in vivo examination of the human sensorimotor system. Cortical and subcortical activity patter ns can be allocated to defined aspects of central motor processes (such as ballistic or sequential movements, imagined movements, writing, etc.) with activation studies. Based on the results of these studies it is possible to compare and to characterise extrapyramidal motor disturbances and to exami ne various pharmacological and interventional therapies (e.g. stereotaxy in Parkinson patients, botulinum toxin in dystonia, etc.). The contribution m ade by PET activation studies towards understanding the pathophysiology of motor disturbances is discussed.