In a recent investigation of the responses to stimulation of the interior of the cerebellum in the normal monkey,1 a medially situated cerebellar system was found, each side of which is capable of exerting a pronounced and rather stereotyped influence on the tonus of the muscles of the eyes, neck, trunk and limbs on both sides of the body. The response of this system to electrical stimulation is ordinarily biphasic, one phase of the reaction being manifest during stimulation and the other appearing as a rebound at the conclusion of stimulation.
The rebound phase of the reaction was always excitatory, leading to contraction of the muscles, producing deviation of the eyes and concavity of the body axis to the side opposite the cerebellar stimulation and also to contraction of the muscles of the limbs, which was reciprocal on the two sides of the body in that the ipsilateral extensor