NEUROPHYSIOLOGICAL PROPERTIES OF PALLIDAL NEURONS IN PARKINSONS-DISEASE

Neuronal properties of the human g lobus pallidus (GP) are not known. Since GP is the major output of the basal ganglia, it may be involved in the pathophysiology of Parkinson's disease. We studied 12 patients with medically resistant Parkinson's disease by using single cell reco rding of the GP during stereotaxic pallidotomy to define neuronal firi ng rate and its modulation during active and passive movements. Differ ent frequency and pattern of single cell activity was found in globus pallidus externus compared with globus pallidus internus. Discharge ra tes of 19% of GP cells were modulated by passive contralateral movemen ts. Pallidal units were most often related solely to single joint move ment. Different patterns of activity in relation to the two different movements of the same joint were often observed. We identified somatot opically arranged cell clusters that alter discharge rate with related movements. These findings suggest at least a partial somatotopic orga nization of the human GP and similarity with experimental results in b oth healthy and MPTP monkeys, providing a rationale for surgical or ph armacological targeting of GP for treating Parkinson's disease.