Nicholas Wetzel

Electroencephalographic changes induced by stimulation of the cerebellum of man

Abstract The human cerebellum was electrically stimulated and alterations in the EEG were observed in 20 out of 26 subjects. 1. 1. The usual response, when posterior cerebellar structures were stimulated, was a change from a low voltage alpha-like frequency or fast frequency patterns to high voltage slow ones. Frequency changes without voltage changes and vice versa could be observed. In each case the dura nearest to the active cerebellar points was stimulated in order to obtain data on possible spread of current. 2. 2. In an occasional patient a low voltage fast record was produced. This was seen more frequently when anterior rather than posterior cerebellar structures were stimulated. 3. 3. In one patient it was possible to induce EEG changes with single electrical shocks. In the other responding patients it was necessary to use bursts of 1 sec or more of stimuli ranging in frequency from 10–300/sec. 4. 4. Disturbances of consciousness were not observed, nor were sensory alterations in the auditory and tactile spheres noted. Changes in visual and proprioceptive sensation were not studied. 5. 5. Epileptiform discharges were not seen. There were no signs of muscular movement resulting from these electrical stimuli.

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.