Cerebello-pallido-thalamic connections in man.

The brains of 5 patients who died at varying intervals following stereotactic pallidotomy or thalamotomy were examined using the Marchi stain for degenerating myelin. In 2 patients, the lesion was directed at the globus pallidus; in 2 the target was nucleus ventralis lateralis, and in 1 the target was n. ventralis posterior medialis. The observations indicated that the globus pallidus is reciprocally connected with n. ventralis lateralis, while the cerebellum is reciprocally connected with n. ventralis intermedius. Degenerating fibers from the medial lemniscus end within n. ventralis posterior, none reaching n. ventralis intermedius. On the basis of cytoarchitecture and subcortical connections, n. ventralis lateralis, n. ventralis intermedius, and n. ventralis posterior appear as distinct entities. However, each nucleus projects to both sensory and motor cortex, suggesting a functional unity.