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Relationship of lesion location to cognitive outcome following microelectrode-guided pallidotomy for Parkinson's disease: Support for the existence of cognitive circuits in the human pallidum. Current models of basal ganglia anatomy posit the existence of multiple parallel, anatomically segregated circuits. Anatomical data from non-human primates suggest that the circuits subserving motor functions are segregated from those subserving cognitive functions. Here we present data that demonstrate that, in humans, motor and cognitive frontosubcortical circuits are segregated. We studied a group of patients with Parkinson's disease undergoing surgical lesioning of the globus pallidus internus for relief of their symptoms. Lesion location along an anteromedial-to-posterolateral axis was found to be related to postsurgical outcome on both cognitive and motor measures. Performance on several neuropsychological measures, including the generation of category exemplars and continuous mental addition, was linearly related to distance along this axis, with anteromedial lesions leading to postsurgical impairment, intermediate lesions having little effect and posterolateral lesions leading to an improvement on several measures. The same relationship was found between memory performance under conditions of proactive interference and lesion location within the globus pallidus internus. In contrast, bradykinesia, assessed as the speed of finger-tapping, had a non-linear relationship to lesion location, intermediate lesions leading to greater postsurgical improvement than lesions in more extreme anteromedial or posterolateral locations. These data demonstrate that the cognitive effects of pallidotomy can be dissociated from the motor effects. These effects depend upon the placement of the lesions within the globus pallidus internus, supporting the segregation of functionally distinct circuits in the human pallidum. Brain 2000 Apr;123(Pt4):746-758 Lombardi WJ, Gross RE, Trepanier LL, Lang AE, Lozano AM, Saint-Cyr JA Department of Neurosurgery, University of Utah, Salt Lake City, UT, USA, Department of Psychology, The Toronto Hospital, Department of Surgery, University of Toronto, Division of Neurosurgery, The Toronto Hospital, Department of Psychology, York University, Movement Disorders Centre, The Toronto Hospital, Department of Medicine, University of Toronto, Division of Neurology, The Toronto Hospital, Departments of Anatomy and Cell Biology and of Psychology, University of Toronto, Toronto, Ontario, Canada. PMID: 10734006 "http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10734006&dopt=Abstract" janet paterson 53 now / 41 dx / 37 onset 613 256 8340 / PO Box 171 Almonte Ontario K0A 1A0 Canada visit my website "a new voice" at: "http://www.geocities.com/janet313/"