N THE neurosurgical treatment of parkinsonian tremor, a major question to be ,answered is, where is the optimum site of target for the lesion? The present study is an attempt to evaluate the posterior ventrolateral area of the thalamus, internal capsule, medial region of the globus pallidus and posterior subthalamus. The comparative value of lesions in these structures was determined by (1) noting differences in reduction of tremor associated with insertion of electrodes, and (~) a comparison of the amount of radio-frequency electrical energy (expressed as Boyle-time factor) necessary to obtain over 75 per cent reduction in tremor. The primary objective of this presentation is to demonstrate that lesions in the posterior subthalamus are the most efficient for reducing parkinsonian tremor. Technique Patients. From a group of 150 parkinsonian patients with varying degrees of tremor and rigidity, only those patients having unilateral or bilateral tremor as the major finding were utilized for this study. Tremor was bilateral in the majority of the 58 patients although usually it was more pronounced on one side. The mean age of the patients was 58 and ranged from 41 to 80 years. All patients had been receiving a variety of medications before operation which did not satisfactorily control the tremor. Patients with bilateral tremor were replaced on medication postoperatively. Since these observations were made in patients distributed over the past 7 years, the traditionally desired 5-year detailed follow-up was not possible. The shortest period of follow-up was 4 months (3 patients). Operation. A total of 7~ operations were performed in the 58 patients. Bilateral operations were done in 6 patients and in 1 it was repeated. Repeated unilateral operations were performed in 6 and the rest of the patients had unilateral procedures. Operations were done with patients

A scheme to enable a biped robot to climb sloping surfaces is proposed in this paper. By means of sensing devlces, namely position sensors on the joints and the force sensors underneath the heel and toe, a biped robot called SD-2 is able to detect the transition of the supporting terrain from a flat-floor to a sloping surface and enable the robot to walk on the slope.

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